Ecological assessment of guadalete river, spain 2012

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Ecological assessment of guadalete river, spain 2012

  1. 1. Assessment of the ecological state of the Guadalete River, Andalucía, Spain Description of the ecological state of the Guadalete River and advice about sustainable usage of the river’s services By STUDENTS BACHELOR OF WATER MANAGEMENT – YEAR 4 Vlissingen, 15-11-2012 Edisonweg 4, 4382 NW, Vlissingen, Netherlands
  2. 2. Justification Title : Assessment of the ecological state of the Guadalete River, Andalucía, Spain Subtitle : Description of the ecological state of the Guadalete River and advice about sustainable usage of the river’s services Date : 15-11-2012 Place : Vlissingen Country : Netherlands Written by : Students Bachelor of Water Management – Year 4 Version : Version 1 Contact : Jasper Verhaar (student no: 00047279) Edisonweg 4 4382 NW Vlissingen Postbus 364 4380 AJ Vlissingen T +31 65 206 76 74 verh0068@hz.nl Institution : HZ University of Applied Sciences Department : Delta Academy Degree : Bachelor of Water Management Course : CU05026 River Basin Management Assignment : Field Study Week 2012 Delivered to : Henk Massink Joao Salvador de Paiva Jouke Heringa Michiel Michels Tony van der Hiele
  3. 3. i Preface The HZ University of Applied Sciences (HZ) class of graduation students of Bachelor of Water Management has been participating in a Field Study Week (FSW) as part of the course River Basin Management. Gaining knowledge about how to investigate a water system including topics such as selecting the correct variables, planning of activities, cooperating, presenting results and so on has been the intention of this FSW. The water system, which has been investigated during this year’s FSW from September 28th till October 5th 2012 (week 39/40), is the Guadalete River in the south of Spain. For the field week, we have formed four different groups. Each group was focusing on a different aspect of the river basin, namely Human Activity, Hydrology, Chemistry, and Biology. Each of our groups has prepared its own activities in weeks 36 till 39 and has been responsible for its field of expertise. The group leaders of each group have been communicating with each other in order to coordinate the investigation. This assessment report is a product of these four groups, formed during the FSW and contains an introduction about the research, applied (field) methods, achieved results, discussion, conclusion and recommendations. We would like to thank various people for their contribution to the Field Study Week of 2012; our supervisors Henk Massink, Joao Salvador de Paiva, Jouke Heringa, Michiel Michels and Tony van der Hiele for their patience in guiding us and the assistance they gave during our research. As the HZ University of Applied Sciences is taking part in the RAAK project “Het Zoute Goud” (The Salty Gold) it was made financially possible to undertake this field week. We would like to extend our thanks to the ‘Stichting Innovatie Alliantie’ (SIA) for this support. Also we would like to thank our international partners at the University of Cadiz and IFAPA for letting us become acquainted with the developments of aquaculture in Spain. Special thanks should be given to Juan Miguel Mancera Romero and Erik-Jan Malta from the University of Cadiz and IFAPA for their support. The willingness of all the researchers at the research center of ‘Centro el Toruño’ as a part of IFAPA to give their time for explaining their work has also been very much appreciated. Special thanks are given to ‘Campus el Sabio’ and Marcos for making our stay in Spain as pleasant as it could get. Have a good time reading! Vlissingen, October 2012 Students Bachelor of Water Management – Year 4 (2012-2013) Wouter Bareman, Kay Bouts, Marta Canto Lopez, João da Cunha Pinheiro Naves Gomes, Marianni de Aragao Nogare, Bart de Clerck, Pieter-Bas Dijkman, Hanneke Ebbeng, Thalitha Ferreira Arruda, Frank Herrewijn, Frauke Hünnekes, Samara Hutting, Daniel Ivanov, João Jacobus, Jan Janse, Benjamin Klemm, Maxim Marcenco, Daan Pijnenburg, Anna Roman, Bart Roothans, Koen Schippers, Friso Snijder, Juliana Spohr Pereira, Xiaodong Tang, Kristiaan van Rooijen, Tim van Roon, Mitra Vaskoska, Jasper Verhaar, Ariany Viana Gomes, Peter Vollaard and Wendy Wösten.
  4. 4. ii Summary The fourth year students of Bachelor of Water Management from the HZ University of Applied Sciences in Vlissingen have conducted an investigation on the Guadalete River in the Province of Andalucía, Spain in October 2012 by means of a field study. The purpose of this field study was to identify the relationship between the ecological state of the Guadalete River and its relation to human activity in the catchment area. A descriptive report about the state has been written including recommendations for more sustainable usage of the river’s ecosystem services by its users. The outcome of this investigation indicates a poor water quality based on biological, chemical and hydrological measurement. Often the oxygen concentrations were below the standard of 5 mg/L and the presence of nutrients such as nitrate and phosphate was clearly measurable. Disruptive structures made by humans (such as dams and in this case wastewater treatment plants) have been pointed out as main causes of these problems. Overexploitation of water from the Guadalete River is believed to be problematic in the sense of lowering of the discharge and therefore the availability and diversity of natural habitat for local flora and fauna. Although it has been said that the Spanish government applies water saving measures, still a lot of water is used for irrigation of crops (mainly cotton) and golf courses. In the past, a weir was constructed relatively far inland to prevent salt water entering upstream zones of the river. This weir, together with large dams may form obstacles for migrating aquatic animals such as fish and crayfish. Challenges for the local government of the region of the Guadalete River lie in providing better treatment of waste- and runoff water by constructing wetlands for the elimination of polluting substances, solving the problem of stratification in the reservoirs during dry periods, building a fish passage at the weir, and keeping the river beds clean of waste and litter that derives from urban areas.
  5. 5. Table of Contents Preface ......................................................................................................................................................................i Summary ..................................................................................................................................................................ii 1. Introduction ........................................................................................................................................................ 1 1.1 Background................................................................................................................................................... 1 1.2 Assignment ................................................................................................................................................... 2 1.2.1 Aim ........................................................................................................................................................ 2 1.2.2 Research question................................................................................................................................. 2 1.3 Chaptering .................................................................................................................................................... 3 2. Research Design .................................................................................................................................................. 4 2.1 Area............................................................................................................................................................... 4 2.2 Planning ........................................................................................................................................................ 4 2.3 Fields of Interest ........................................................................................................................................... 5 2.3.1 Human Activity ...................................................................................................................................... 5 2.3.2 Biology................................................................................................................................................... 5 2.3.3 Hydrology .............................................................................................................................................. 6 2.3.4 Chemistry .............................................................................................................................................. 6 3. Human Activity.................................................................................................................................................... 8 3.1 Methods........................................................................................................................................................ 8 3.1.1 Stakeholder Interviews.......................................................................................................................... 8 3.1.2 Literature Research ............................................................................................................................... 9 3.2 Results........................................................................................................................................................... 9 3.2.1 Policy and Legislation ............................................................................................................................ 9 3.2.2 Water Users........................................................................................................................................... 9 3.2.3 Wastewater Treatment ....................................................................................................................... 13 3.3 Discussion ................................................................................................................................................... 15 3.4 Conclusion................................................................................................................................................... 15 4. Hydrology.......................................................................................................................................................... 17 4.1 Method and Materials................................................................................................................................ 17 4.1.1 Discharge of the River ......................................................................................................................... 17 4.1.2 Tidal Influence ..................................................................................................................................... 18 4.1.3 Total Suspended Solids........................................................................................................................ 19 4.1.4 Erosion................................................................................................................................................. 19 4.2 Results......................................................................................................................................................... 21 4.2.1 Discharge of the River ......................................................................................................................... 21 4.2.2 Tidal Influence ..................................................................................................................................... 21 4.2.3 Total Suspended Solids and Erosion.................................................................................................... 22 4.3 Discussion ................................................................................................................................................... 23 4.4 Conclusion................................................................................................................................................... 24
  6. 6. 5. Chemistry .......................................................................................................................................................... 26 5.1 Method and Materials................................................................................................................................ 26 5.1.1 Field Measurements............................................................................................................................ 26 5.1.2 Laboratory Measurements.................................................................................................................. 27 5.2 Results......................................................................................................................................................... 27 5.2.1 Field Measurements............................................................................................................................ 27 5.2.2 Laboratory Measurements.................................................................................................................. 30 5.3 Discussion ................................................................................................................................................... 34 5.4 Conclusion................................................................................................................................................... 34 6. Biology............................................................................................................................................................... 36 6.1 Method and Materials................................................................................................................................ 36 6.1.1 Macrofauna Sampling ......................................................................................................................... 36 6.1.2 Macrophyte Sampling ......................................................................................................................... 38 6.1.3 Biotic Index.......................................................................................................................................... 38 6.1.4 Ecological Quality Ratio....................................................................................................................... 39 6.2 Results......................................................................................................................................................... 40 6.2.1 Biotic Index.......................................................................................................................................... 40 6.2.2 Ecological Quality Ratio....................................................................................................................... 41 6.2.3 Macrophytes........................................................................................................................................ 41 6.3 Discussion ................................................................................................................................................... 43 6.4 Conclusion................................................................................................................................................... 43 7. Comprehensive Discussion................................................................................................................................ 46 8. Comprehensive Conclusion............................................................................................................................... 47 9. Recommendations ............................................................................................................................................ 49 9.1 Sufficient treatment of wastewater/irrigation water................................................................................. 49 9.2 Oxygen level................................................................................................................................................ 52 9.3 Concrete weir ............................................................................................................................................. 53 9.4 Waste/litter in and around the river .......................................................................................................... 54 9.5 Research ..................................................................................................................................................... 54 10. Literature......................................................................................................................................................... 55 Appendix I: Example of erosion calculation.......................................................................................................... 58 Appendix II: Cross-sections and hydraulics........................................................................................................... 59 Appendix III: Flow velocity .................................................................................................................................... 64 Appendix IV: Time lapse pictures of water level fluctuation at weir .................................................................... 65 Appendix V: Field and laboratory data chemistry................................................................................................. 66 Appendix VI: Result tables macrofauna ................................................................................................................ 68 Appendix VII: Result tables macrophytes ............................................................................................................. 71
  7. 7. 1 Assessment of the ecological state of the Guadalete River, Andalucía, Spain 1. Introduction 1.1 Background The Guadalete River is a river in the Spanish region Andalucía and originates from ‘Sierra de la Grazalema’ at a height of 1000 meters above sea level. The river has a total length of 172 km and meets the Atlantic Ocean at the Bay of Cadiz via El Puerto de Santa Maria south of Cadiz (see figure 1.1) (Rutas Rurales en Cadiz). On its way the Guadalete River receives water from the Majaceite River as one of its major tributaries (El Rio Guadalete). The Guadalete River is part of the Guadalete and Barbate river basin (see figure 1.2). The relatively high average temperature of 16.8°C and long periods of drought in the region of the Guadalete River result in high uptake of water for multiple purposes. During short periods of heavy rainfall the dry soil can easily be flushed away with runoff water into the surface water. This may result in high concentrations of nitrogen from soil fertilizers and the presence of toxins from pesticides (Deputacion de Grenada 2010). Figure 1.1 Location of Guadalete River (source: FSW manual and Google Earth) Since the construction of a number of dams in the Guadalete River itself and in its major tributary the Majaceite River, the character of the river system is no longer hundred percent natural. Dams were built to create reservoirs which are man-made lakes serving in water supply for drinking water, irrigation and flood protection. Between 1900 and 1950 the number of reservoirs in Spain had a growth rate of more than four per year and reached a number of 741 by 1975. Today, there are 1172 large dams. The effect of dams on the natural character of a river can be enormous; the hydrological cycle will change and subsequently affect the ecological state. In particular fish will have major problems migrating up and down a river that is dammed (European Environment Agency).
  8. 8. 2 Assessment of the ecological state of the Guadalete River, Andalucía, Spain Figure 1.2 River basin ‘Guadalete and Barbate’ 1.2 Assignment Graduation students of Bachelor of Water Management of the HZ University of Applied Sciences are assigned to describe the aquatic system of the Guadalete River by means of planning an investigation, conducting measurements on the river, and writing an informative/advisory report. The students should learn about the functioning of the river by measuring hydrological, chemical and biological variables. Moreover, the assignment functions as an opportunity for the students to apply theoretical and practical knowledge about water management – gained during their study at the HZ – to a real case scenario. 1.2.1 Aim The aim of this investigation is to analyse the relationship between human activity along the Guadalete river (in terms of policy & legislation, water usage, and wastewater treatment) and ecological functioning of the Guadalete river (in terms of hydrology, chemistry and biology) in order to advice local authorities about sustainable use of the river’s services. 1.2.2 Research question The main question which should be answered during this investigation can be described as follows: How can the relationship between human activity along and ecological functioning of the Guadalete River be described, and how can this be transformed into an advice about sustainable usage of the river’s services?
  9. 9. 3 Assessment of the ecological state of the Guadalete River, Andalucía, Spain 1.3 Chaptering This report is structured according to four disciplines; Human activities, Hydrology, Chemistry and Biology respectively presented in chapters 3, 4, 5 and 6. Prior to this, in chapter 2, the design of the research is given in which the research area, planning and theory of the disciplines are described. In chapter 7 and chapter 8 comprehensive discussion and comprehensive conclusion of the results are given respectively. The main section of this report is rounded off in the form of recommendations in chapter 9 in which the conclusions of this study are transformed into an integrated advice.
  10. 10. 4 Assessment of the ecological state of the Guadalete River, Andalucía, Spain 2. Research Design 2.1 Area The area of the Guadalete river that is investigated in this study stretches from the dam of the reservoir located at the city of Arcos de la Frontera (50 km northeast from Cadiz as the crow flies) to the mouth of the river at the city of El Puerto de Santa Maria were it enters the Bay of Cadiz. The length this stretch is approximately 170 km. Figure 2.1 Location and water related features of the Guadalete River in Spain The upstream area of the stretch lies in an area which is characterized by hills and steep slopes combined with small urban areas and agricultural rural areas of Arcos de la Frontera. Further downstream it gradually changes into a more flattened landscape consisting of mainly agricultural parcels and small cities and villages near the river. Closer to the river mouth the Guadalete passes the south side of the relatively large city of Jerez de la Frontera. Finally, the Guadalete river enters the Bay of Cadiz just after passing by the city center of El Puerto de Santa Maria (see figure 2.1). 2.2 Planning The Guadalete River is investigated by a team of student engineers during the first and second day of October, 2012 and half of the subsequently day of field study. During this period of time standardized research methods were used to extract data which can even be understood by people with little to no knowledge about water management. The team of student engineers (Bachelor of Water Management) consists of twenty-nine persons of whom seven are exchange student with a background of Civil Engineering in Brazil and Biology in Spain. The regular (twenty-three) student engineers are enrolled in the fourth year of the Bachelor of Water Management program and are expected to graduate in the summer of 2013. Their background knowledge consists of an integration of biological, hydrological, chemical, and social aspects of fresh and saline (global and local) water system management.
  11. 11. 5 Assessment of the ecological state of the Guadalete River, Andalucía, Spain Although it would be logical to use the European Water Framework Directive (EWFD) as a guideline for this investigation, it has only partly been adopted here. Moreover, instead of Spanish assessment methods, Dutch assessment methods have been applied. The main reason for this is that the Spanish Government does not (yet) applies this directive to their water systems. This makes it not possible to use specific Spanish standards. Moreover, due to a limited period of field study time (2.5 days) and preference for a maximized number of sampling points it would be more beneficial to investigate only the basic characteristics of the river system instead of a wide arrange of parameters. 2.3 Fields of Interest The Guadalete river is investigated according to four different disciplines (or fields of interest), namely: Human Activity, Hydrology, Chemistry and Biology. The following paragraphs introduce the disciplines in terms of aim and motivation. Methods, results, discussion and conclusion of each discipline can be found in the subsequent chapters 3, 4, 5 and 6. 2.3.1 Human Activity This discipline describes the impact of human activity along the river, taking into account: policy & legislation, water users (aquaculture, agriculture, industries, and recreation), and wastewater treatment. By means of interviews with stakeholders and literature research important information is gathered which can be connected to the other fields of interest in this research. It is important to know how the activities of human that live near the Guadalete River influence the ecological state of the river in terms of biology, hydrology and chemistry. Straight forward we could say that there is some kind of influence anyway since humans are part of the ecosystem for thousands of years. However, the population of the Cadiz region has not always been as high as it is today, while the Guadalete River and its catchment area and water regime (based on climate) did not change in such a high rate. Most likely this results in a growing pressure on the ecological functioning of the river system. Under the discipline of ‘human activity’ as part of this study, we aim on identifying the human activities that are expected to have a major influence on the ecological state of the Guadalete River. 2.3.2 Biology This discipline describes the biological aspects of the Guadalete River and surroundings. The emphasis of the Biology discipline lies on the identification of macrofauna and macrophytes living in and near the water. Based on the species that are found an estimation of biological quality of the river system can be made and connection to the other disciplines can be laid. In order to perform a multi-habitat measurement sampling of the macrofauna, all the present habitats at the location should be sampled. Furthermore it is very important to take samples in the right (optimal) time of year, to get a good representation of the present macrofauna. The ideal conditions for collecting macrofauna samples in freshwater habitat is once or twice a year. The samples can be collected from March till October (in order to apply the EWFD). Samples are to be collected in such a way that the samples represent the water body. Manmade constructions should be avoided, for they might disturb the sampling and the results from it. A multi-habitat sampling method should be applied from the riparian zone till the deeper water.
  12. 12. 6 Assessment of the ecological state of the Guadalete River, Andalucía, Spain 2.3.3 Hydrology This discipline describes the hydraulic and hydrological elements of the river system in terms of qualitative and quantitative aspect. Important aspects to this area of research are: flow velocity, flow rate (discharge), tidal influence, and erosion/sedimentation. Basic information about flow rate (based on flow velocity and cross-sectional area) is collected for the Guadalete River and its tributaries. Such information can be important to resolve question not only related to hydrology, but also to the other fields of interests of this study. The Guadalete River ends in the bay of Bay of Cádiz, therefore we assume there is at least a part of the river which is influenced by the tide. It is important to know how far this tidal influence reaches upstream. Probably this will be till the weir south of El Portal (see figure 2.2). To test this hypothesis a measurement of the water level right after the weir (downstream) is performed. The water level is measured every thirty minutes for a couple of hours. In this way, if there is indeed tidal influence, the water level will rise or decline. The hypothetical water level rise or decline will be connected to a rise or decline of the tide in the Bay of Cádiz. Figure 2.2 Weir located south of El Portal Sediments play an important role in the elemental cycling in aquatic environments. Most sediment in surface waters originates from surface erosion. For the purposes of aquatic monitoring, sediments can be classified as deposited or suspended. Deposited sediment is that found on the bed of a river or lake. Suspended sediment is that found in the water column where it is being transported by water movements. Many suspended sediments means there is a low visibility. And a low visibility will influence the algae growth and biological activity in and around the river. Therefore a measurement to determine the total suspended solids (TSS) is conducted. 2.3.4 Chemistry This discipline describes the chemical aspects of the river system, taking into account: oxygen concentration, pH, salinity, temperature and nutrient concentration. Combined, this discipline can present the water quality and the transport of different substances in the Guadalete River obtained by field measurements (see figure 2.3) and laboratory analyses.
  13. 13. 7 Assessment of the ecological state of the Guadalete River, Andalucía, Spain Oxygen is necessary for life in water. If the value is lower than 5 mg/L, there is an increased risk of oxygen deficiency for heterotrophic organisms. The pH is a very important indicator for the condition of the water system. The pH also indicates the presence of carbon dioxide in the water as in most water systems carbon dioxide and carbonates have a large impact on the pH. The salinity is important because the influence of the tide could be determined based on this. Ammonium (NH4 + -N), nitrite (NO2-N), and nitrate (NO3-N), taken together as dissolved inorganic nitrogen (DIN) are important nutrients in the nitrogen cycle. The nitrogen cycle consists of different important processes like nitrogen fixation, mineralization, nitrification and denitrification. The measured parameters are key elements in these processes so they can give a good insight about the nitrogen conversion into various chemical forms in the aquatic system of the Guadalete River. Ortho-phosphate (PO4 3— P) is an important nutrient because it is often responsible for eutrophication in ecosystems. Eutrophication means that there are too many nutrients in the water. This could lead to an algae bloom and eventually to oxygen deficit. It is also a key element in most fertilizers so it can give a relationship between human activity and ortho-phosphate concentrations found in the Guadalete River. Figure 2.3 Field measurements to determine chemical water quality of the Guadalete River
  14. 14. 8 Assessment of the ecological state of the Guadalete River, Andalucía, Spain 3. Human Activity Human activities which are believed to have a significant effect on the ecological state of the Guadalete River have been investigated during this study. In this chapter the influences of human activity, namely policy & legislation, water users, and wastewater treatment, are described in terms of methods, results, discussion, and conclusion. 3.1 Methods 3.1.1 Stakeholder Interviews Interviews with stakeholders of the Guadalete River were conducted during the two field days in Spain (see figure 3.1). Via internet sources and literature a select list of different types of stakeholders was created including municipalities, crop- and fish farmers, recreational facilities, and waste water treatment plants. For each type of stakeholder a specified list of questions was prepared. By e-mail and telephone the stakeholders were contacted and appointments for face-to- face interviews were made possible. Figure 3.1 Interview with staff members of municipality of El Puerto de Santa Maria. From left to right: Ceferino Delgado Gómez (legal advisor municipality), Juan Carlos Neva Delgado (biologist municipality), Juliana Spohr (student HZ University), Joao Jacobus (student HZ University), and Joao Salvador de Paiva (supervisor HZ University)
  15. 15. 9 Assessment of the ecological state of the Guadalete River, Andalucía, Spain 3.1.2 Literature Research Literature research was performed before, during and after the field days in order to find supportive data for the findings in the field. Scientific articles, webpages, textbooks and journals have been studied to find background information about the selected aspects of human activity along the Guadalete River. 3.2 Results 3.2.1 Policy and Legislation For a better understanding of the Spanish legislation and in order to clarify the mechanisms of administration of water from the Guadalete River, an interview was conducted with the environment department of the city of El Puerto de Santa Maria. The biologist responsible for environmental planning Juan Carlos Neva Delgado and Ceferino Delgado Gómez (legal advisor) reported that from the year 1979 each province is recognized as an autonomous community with its own normative. In the case of Guadalete River, managed by the province of Andalucía, it is worth remembering that the river lies within a single province. For this reason the administration is responsibility of Andalucía. However, in cases where the rivers cut more than one province administration responsibility is for the federal government. Each province is provided with its own wastewater treatment, but, in the case of Guadalete province, many of them have only a primary treatment with no chemical treatment. Nevertheless, the province classifies the quality of the Guadalete River as ‘Excellent’. The biologist Juan Carlos emphasized the return of many native species that had disappeared from the river and now, after 30 years, are returning to their habitat. Even with the return of biodiversity, other species such as lobster and corvina that used to be benefited by the incoming salt water and going up the river to reproduce, today cannot overcome the small weir built at the entrance of the river, restricting their reproduction area. This weir was installed to reduce salt water intrusion during high tide. In addition native fish species disappear due to illegal introduction of ‘sport fish’ (invasive) species. However, the government does provide licenses for fishing on these species. 3.2.2 Water Users Aquaculture In Andalusia and near the Guadalete River, aquaculture is the one industry that can be seen most often. Because of the tidal influences of the area the investment in onshore aquaculture business soon became profitable. Extensive culture of fish, mollusks and crustaceans are most common in old salt marshes or “Salinas” that were used for the production of salt. These Salinas were turned into aquaculture facilities which are called “Esteros”. In 2001, the Ministry of Agriculture and Fisheries was founded and the development of aquaculture plants and business has grown a lot. Now, in the province of Cadiz, there are 35 land based marine aquaculture and 3 sea based sites. The marine aquaculture is the best feasible option because of the big influence of the Atlantic Ocean at the aquaculture zone. The province of Andalucía is known for its production of dorada or sea bream (see figure 3.2), which take up 64% of the total production of almost 7.500 tons. Still this total production is increasing every year as there are a lot of experiments done on types of aquaculture (Rivero et al, 2004).
  16. 16. 10 Assessment of the ecological state of the Guadalete River, Andalucía, Spain Figure 3.2 Example of land-based sea bream cultivation in Andalucía, here at research center IFAPA ‘Centro el Toruño’ The effect of an aquaculture business on the river system is completely depending on the types of culture and the techniques that are used. Sea bream and sea bass are the most exploited species in the province of Cadiz, where they mostly combine these farms with the production of salt. When looking at the usage of water in these plants you see that there are low numbers of net water losses. Most of the combined and extensive aquaculture plants use sea-water and little water from the Guadalete River. The water is not pretreated and also after usage it is not treated most of the times. However, because of the natural character of these extensive plants the water is not much polluted at all. Fish are mostly fed trough enriching the water with phyto- or zooplankton, or when there are enough living organisms in the water no enhancing takes place at all. In this way there is not much pollution of the river nor of the sea. There is also no control on the effluent water though, which can be necessary to check if water treatment is needed. Agriculture For many centuries, Andalusia’s society was mainly agriculture. Even today, 45% of the Andalusia territory is cultivated. However, looking at the Guadalete – Barbate river basin (see figure 3.3) a total irrigation area of about 60,498.9 ha is used for agricultural purposes. The by far biggest irrigated area is cultivated with cotton crops, which occupies an area of about 14,250 hectares, followed by winter crops with about 10.3 ha. The third largest group is made up by sunflowers and outdoor horticultural crops 12.4% (7,510 ha) and 11.8% (7,165 ha) of the surface area, respectively. High usage of water consumption for agriculture use comes from large irrigation schemes such as the Guadalcacín area or the Northwest Coast of Guadalete – Barbate river basin. These areas require a total volume of 199.3
  17. 17. 11 Assessment of the ecological state of the Guadalete River, Andalucía, Spain hm3 of gross water demand (62% of total volume), where 58% is used for irrigation of the crop fields, namely 34.9 ha. Figure 3.3 Guadelete-Barbate river basin with irrigation water sources (source: Junta de Andalucía) The water used in the Guadalcacin area for irrigation comes mainly from surface water, namely the Guadalete River and other surface waters, which make with 272,80 hm3 , 85% of the irrigation water, followed by underground water (39.02 hm3 ), which is extracted from dwells in the area (see figure 3.4). Figure 3.4 Sources of water used for irrigation in the Guadalete-Barbate river basin (source: Junta de Andalucía)
  18. 18. 12 Assessment of the ecological state of the Guadalete River, Andalucía, Spain Industries In Spain, Jerez de la Frontera is the main capital for production, procession and distribution of sugar. The sugar beet production is part of a crop cycle where settling ponds store and recycle water. These water reserves attract in many times different types of amphibians, reptiles and mammals. Also, in Spain, the wetlands created by the company of Azucarera combine the ponds for an industrial use of water with the development of wildlife. Populations of Flamenco birds flourish in the ponds of Azucarera (International Confederation of European Beet Growers & Comité Européen de Fabricant de Sucer, 2012) The market leader in Spain “Azucarera” produces around 90.000 tonnes of sugar per year. Because of the size of the company it provides thousands of jobs at the Port of Cadiz. For the growth of the sugar beets the company is highly dependent on the water provision from the area. Therefore the water reservoirs in the upstream part of the river Guadalete River are of big importance for Azucarera and the growth of the sugar beets. For providing a higher level of sustainability within the production of sugar the company invested in a fermentation tank, a central distributor for southern Ibiria and increased the production of sugar from imported sugar canes (F.C. Aleu, 2012). To improve the usage of water at the beginning of the chain, where the sugar beets are being produced, research is being done to get a better grip on the water management of the farmer. The price of water can change in Spain due to possible drought. Therefore different optimizations can be made to save water and energy during the growing period of the sugar beets. Here you can think of the water price but also the energy required raising the water to a certain height for irrigation, the cost for maintenance of the water pumps, irrigation equipment and so on. There has been done a lot of research to find an optimum in the use of water, but there is still more research needed to make an integrated approach (Velicia, H., 1996). Recreation Spain is known as one of the most popular holiday countries in the world. Especially in summer – when the climate is hot and dry – hotels and residential villas are highly occupied. However, during the yearly holiday season a lot of water is used by tourist. For example, an average Spanish citizen uses approximately 250 liter of water per day, while the average tourist uses 440 liters. This number can even get doubled if the tourist uses swimming pools and golf courses as well (WWF 2001). Overall, the tourist water consumption has increased since 1994 by about 80% (Stefano 2004). Cities and villages near the Guadalete River facilitate many tourists each year. Arcos de la Frontera for example is famous for its scenic white houses and steep cliffs on which they are built on. Furthermore, El Puerto de Santa Maria and Cadiz, positioned at the Bay of Cadiz, attract many tourists for their historic city centers and many beaches. It is expected that like the general trend in Spain tourists near the Guadalete River use a lot of water too. In the province of Cadiz five golf clubs with a total of nearly 330 ha of grass fields are located relatively close to the Guadalete River. Although the water consumption of a golf course depends on many factors such as size, weather conditions and soil characteristics an estimated volume of 2,500 m3 per day can be used on a hot day. On average a standard 18 hole golf course (with an irrigated surface of 54 ha) might consume around 0.3 Hm3 per year (Salgot 2012).
  19. 19. 13 Assessment of the ecological state of the Guadalete River, Andalucía, Spain Golf club ‘Sherry Golf Jerez’ in Jerez de la Frontera says to use mainly rain water to irrigate their fields. The rain water is collected from land uphill during the rainy periods of the years and stored in the ponds on the golf course (see figure 3.5). By reusing its own irrigation water it sporadically happens that there is a shortage (according to personal communication with a representative from ‘Sherry Golf Jerez’). When there is a shortage in extremely dry seasons, the golf club says to buy water from a local supplier (reused water) and does not extract water directly from the Guadalete River nor aquifer by themselves. Figure 3.5 Northern part of 'Sherry Golf Jerez' with its many ponds (dark green areas) which are used for (re)capturing of water 3.2.3 Wastewater Treatment Facilities The wastewater treatment plant (WWTP) of Jerez de La Frontera, better known as EDAR Guadalete (see figure 3.6), treats an average volume of 70,000 m³ wastewater per day. This amount of wastewater is mainly from the urban area of Jerez de La Frontera itself, Guadalcacin, Los Albarizones, La Corta, El Portal and Estella. That way, the main two cities that contribute for the amount of wastewater are Jerez and Estella, with nearly 211,000 habitants and 14,000 habitants respectively, according to the city hall websites. All the other areas are part of Jerez or too small to be considered (for an example, the Los Albarizones, being part of Jerez, and with only 420 habitants). The total amount of habitants who use the services of the EDAR Guadalete are around 225,000, but the facility has a capacity to treat water from 250,000 habitants.
  20. 20. 14 Assessment of the ecological state of the Guadalete River, Andalucía, Spain Figure 3.6 Wastewater treatment plant of Jerez de la Frontera with effluent discharge in the Guadalete River (bottom) According to the company which provides the service of wastewater treatment of Jerez de La Frontera, Aguas de Jerez, the plant has three phases of treatment. The wastewater first passes through a pre-treatment that removes the grease and sand from the wastewater. After that, the actual treatment starts, first with a decantation, that produces the first sludge, and then with a biochemical reactor with recirculation, which produces more sludge. Finally, the water passes through two banks of mercury lamps, consisting of ultra-violet disinfection. The whole process is considered to be a full tertiary wastewater treatment system. The executive company Aguas de Jerez states that the wastewater treatment plant’s effluent has such good quality that it is usable for reutilization for some municipalities’ services, such as watering green public places or some private services such as watering the golf courses. Unfortunately is not possible the reutilization for residences, mainly because of the concentration of E. coli (between 0 and 200 UFC/100mL) and suspended solids (between 10 and 20 mg/L). Policy of waste water There are many laws concerning water spill and wastewater in Spain. In this maze of legislation and organizations, we could find some of the most important regulations and directives for the effluent from a wastewater treatment plant, and who is responsible for monitoring this effluent. First of all, the “Organismos de Cuenca” (Basin Organizations in free translation) is responsible for the monitoring of the wastewater (according to “Art. 21 of the Ley de Aguas of 08/08/1985” in Spain’s Water Law). With that in mind, the “Confederación Hidrográfica de Guadalquivir” is the responsible for the planning, management and controlling of the Guadalete Basin. Even though this organization system seems straight forward, there are many other laws and organizations responsible for parts of the river basin system control. Because of this, the policies in Spain are sometimes like a web that merges with the European legislation, making a confusing background to what should be a simple and important law.
  21. 21. 15 Assessment of the ecological state of the Guadalete River, Andalucía, Spain 3.3 Discussion The information we have collected during the stakeholder interviews and literature research is valuable in the sense of confirming our predictions about the influence of human activity on the ecological state of the Guadalete River. We are now able to give an indication whether the selected activities performed by the selected stakeholders of the river have significant effects or not. However, the quality of the collected data should be very well discussed here. Stakeholder interviews did not provide us the amount of information that we were expected to get. It turned out that many of our selected contacts were not available for questions for a variety of reasons. Much of the information given in this chapter is therefore coming from a small amount of sources; mainly literature which might be old dated and even revised by now. Due to the limited amount of information from interviews it was difficult or not possible to compare opinions of stakeholders active in the same branches. Such information would have been highly valuable since it gives different points of views which would have made our results less subjective. Regarding the results of the different types of human activities presented in this report we can say that all but one type complies with our prediction of influencing the ecological state of the Guadalete River. That one type turns out to be the aquacultural activities in the region of the river since not many companies use fresh water in their systems. The reason for this ‘false’ prediction probably lies in the preparation of our research. More intensive research would have shown beforehand that these companies do not use fresh water from the Guadalete River. The types of human activity that do comply with our predictions – having significant influence on the river’s ecological state – do not interfere with the widely accepted views on such topics. It is generally known that a wastewater treatment plant has a major effect on the environment (positive or negative according to its functioning) for instance. And that domestic and industrial use of river water is influencing the water regime of a river is already known. Nevertheless, the confirmation of human activities being present in the region of the Guadalete River and the (limited) data will be anyway useful for answering the question of the other fields of interest and for answering the main question of this investigation. 3.4 Conclusion The aim of investigating the human activities of the Guadalete River was to test whether the selected activities (policy & legislation, water usage, and wastewater treatment) actually have a significant impact on the river’s ecosystem. We have tested this by interviewing stakeholder whom perform such activities and by studying literature. The expectation was that the three types of activities had a significant impact. Policy & Legislation The management of the Guadalete River falls under the responsibility of the Province of Andalucía since this is the only province in which the river is located. In cases of rivers which cross multiple provinces another policy is applied, namely that the responsibility is for the federal government. We presume that the management of a river which falls under the responsibility of a province (such as the Guadalete River) is better managed compared to a governmental-managed river. Most likely a province has much more (historic) knowledge about a river than that a large institution would have. Still, we have identified some contradictions in the qualification of the Guadalete River by the
  22. 22. 16 Assessment of the ecological state of the Guadalete River, Andalucía, Spain managing province; according to our sources the river is qualified as ‘Excellent’ by the province, while municipal experts agree on the need of improvement of migration routes of certain organisms. Moreover, we have found out that release of exotic species of fish into the Guadalete River is forbidden while the permits handed out for sport fishing are based on the presence of such species. Water Usage The extraction and discharge of water by aquaculture companies does not seem to have a significant effect on the ecological state of the Guadalete River. The majority of aquaculture companies cultivates saline species and therefore uses salt water from the Bay of Cadiz. Feed that is used in these companies are mostly cultivated by the companies themselves. Agriculture in the region of the Guadalete River makes up a very large part of the total water use of the river. Cotton is the type of crop that is cultivated most in this area and therefore consumes the majority of water. 85% percent of the total volume of water used for irrigation derives from surface waters such as the reservoirs of the Guadalete River. According to our results industries near the Guadalete River make use of river water. They do not extract the water from the river directly but indirectly they use it by buying water from the reservoirs in the Guadalete and Majaceite River. The extraction of water from these reservoirs must have an impact on the ecological function of the river since less water is left for organisms to inhabit the area and habitat is expected to be less diverse. However, businesses like the sugar factory discussed earlier in this chapter do benefit from water saving measures in times of scarcity. We can make the same statement for recreational activities along the Guadalete River; the more activities take place in forms of tourist attraction, the more water is used from the reservoirs. An increase in number of tourist in the region of Cadiz is expected and therefore a higher pressure on the water availability for the river itself. Wastewater Treatment If, according to information found on the website of “Aguas de Jerez” (managing company of the wastewater treatment plant in Jerez de la Frontera), the process of tertiary wastewater treatment functions as it should, the effect of this activity should be positive for the Guadalete River’s ecosystem. The plant’s capacity is said to be higher than the number of people served at the moment so no problems are expected. However, the local newspaper reported a strike of the employees from “Aguas de Jerez”, they were complaining about the inefficiency of the water treatment, in addition reported that some liters of sewer were thrown into the river without any treatment. This story can be confirmed by many surrounding dwellers who also complain about the water quality of the Guadalete River. Even though all those problems without the presence of this wastewater treatment facility (and the other smaller ones in the region) the state of the river would have been much worse. Nevertheless, proper wastewater treatment is a standard for today’s society and therefore it should be logical that every modern household is connected to the sewage system. It turned out not be the case in the old city centers of Jerez de la Frontera and El Puerto de Santa Maria, resulting in the discharge of untreated wastewater into the Guadalete River.
  23. 23. 17 Assessment of the ecological state of the Guadalete River, Andalucía, Spain 4. Hydrology The hydraulic and hydrological elements of the river were investigated in a stretch of approximately 110 km running from the point where the Majaceite river meets the Guadalete river till the mouth of the river in the Bay of Cadiz (see figure 4.1). In this chapter the analysis of the influences of the hydrology in terms of qualitative and quantitative aspects of the river is described in terms of methods, results, discussion and conclusion. Sampling point code: 10 20 30 40 50 60 100 110 120 130 140 150 160 170 180 Distance from starting point (km): 0 6 23 24 34 39 56 67 73 75 84 86 92 99 107 Figure 4.1 Map of Guadalete River with sampling points for hydrological measurements 4.1 Method and Materials 4.1.1 Discharge of the River To determine the discharge (Q in m3 /s), two different parameters should be known: (1) the velocity (v in m/s) and (2) the surface area (A in m2 ) of the cross section of the river. By using equation (E4.1) the discharge can be calculated. ܳ = ‫ݒ‬ ∗ A (E4.1) The cross-sectional area is determined by stretching a tape across the river channel (L total (in m)) and measuring the depth of the water level at different points (D1, D2, etc. (in m)) along this tape (see figure 4.2). By doing this, different sub-segments are created with a specific area which can be calculated by using equation (E4.2) (see figure 4.3). ሺ2 × 0,5‫݃ݏܮ‬ሻ × ݀݁‫ݐ݌‬ℎ (E4.2)
  24. 24. 18 Assessment of the ecological state of the Guadalete River, Andalucía, Spain Figure 4.2 Measuring the river’s depth with a scaled pole The area for the segment can be calculated by using the 2 depths (D1 and D2) and the trapezium formula (E4.3). At the same place as the depth measurements (D1, D2 etc.) the velocity is measured with a digital water velocity meter (V1, V2 etc. in m/s). The sub segment 2 velocity is calculated by taking an average of V1 and V2, which should give you the velocity in the middle (4.3, green line) of the segment (E4.4). Then the discharge of the different sub-segments is calculated with equation E4.1. The total discharge is calculated with E4.5. See figure 4.3 for additional information. Asg2 = (Lsg2*(D1 + D2))/2 ` (E4.3) Vsg2 = (V1 +V2) /2 (E4.4) Qtotal = Qsg1 + Qsg2 + Qsg3 +Qsg4 etc. (E4.5) Figure 4.3 Diagram of method to determine cross-sectional area (blue line indicates the water level) 4.1.2 Tidal Influence To determine whether there is tidal influence up to the weir near El Portal, a distance of 16km from the mouth of the river, fluctuation of the water level right after (downstream) the weir is
  25. 25. 19 Assessment of the ecological state of the Guadalete River, Andalucía, Spain determined. During a period of three hours the water level is measured every thirty minutes. In this way, if there is indeed tidal influence, the water level will rise or decline. The hypothetical water level rise or decline will be connected to a rise or decline of the tide in the Bay of Cádiz. 4.1.3 Total Suspended Solids At different sample locations a plastic bottle is filled with river water. This is done as far away from the riverbank. This river water is filtered through filter paper to determine the dry weight of the suspended sediment. The value of total suspended solids (TSS in mg/l) is calculated by using equation (E4.6). ܶܵܵ = ୈ୰୷ ୵ୣ୧୥୦୲ି୤୧୪୲ୣ୰ ୵ୣ୧୥୦୲ ୚୭୪୳୫ୣ (E4.6) 4.1.4 Erosion Different samples of the river soil is taken and compared with a ‘sand standard rural’ (or sand ruler) (see figure 4.4) to determine D50 and D90. Figure 4.4 ‘Sand standard rural’ with soil sample (centered) and different comparative samples to determine D50 and D90 When the D50 and the D90 is found, equation (E4.7) is used to determine the critical velocity (a = 0.28 for sand, a = 0.12 for clay). This means when the river at this specific point has a higher velocity than the critical velocity erosion (sediment transport) will occur. Equations (E4.8) and (E4.9) are used to calculate Ck. See appendix I for an example calculation. ‫ ݒ‬ = ܽ × ‫ܥ‬௞ × ඥ‫ܦ‬ହ଴ (E4.7) V = critical velocity at which the material starts moving (m/s) a = factor depending on the density of the material Ck = Chezy’s coefficient (m½ /s) d90= “maximum” grain size, 90% (m) ‫ܥ‬௞ = 18log ଵଶୖ ஽వబ (E4.8) R = hydraulic radius (m)
  26. 26. 20 Assessment of the ecological state of the Guadalete River, Andalucía, Spain ܴ = ஺ ை (E4.9) A = cross sectional flow area (m2 ) O = wetted perimeter With the help of the Hulström diagram (see figure 4.5) it can be determined under which circumstances (relation between flow velocity and grain size) erosion, deposition or transport of sediment occurs. Figure 4.5 Hulström diagram indicating erosion, transport or deposition of sediment according to flow velocity and grain size
  27. 27. 21 Assessment of the ecological state of the Guadalete River, Andalucía, Spain 4.2 Results 4.2.1 Discharge of the River In figure 4.6 the results of discharge calculations are presented in a graph. Detailed data of cross- sectional area and flow velocity needed to calculate the discharge can be found in appendix II and appendix III. Figure 4.6 Discharge of the Guadalete River in m 3 /s as a function of the distance along the river in kilometers. The x-axis starts at the most upstream sampling point (20), indicated by zero. It ends at the most downstream point at the weir (150). Besides the weir, two other points are indicated in the graph; the addition of water from a side river (Majaceite) and the water from the WWTP of Jerez de la Frontera. The arrow indicates at which point it is located along the Guadalete (it is not a separate measuring point). The polynomial line gives an indication of the trend of the discharge along the river. 4.2.2 Tidal Influence The measurement to determine the fluctuations in the water level right after (or at) the weir is shown in figure 5.7 where the water level at the weir (red line) between 15:45 PM and 18:45 PM and the water level in the Bay of Cádiz (blue line) on 3 October 2012 are presented. Note that the y-axe corresponds with the water level in the Bay of Cádiz but not with the water level at the weir. For the water level at the weir only a fluctuation is shown. However, time lap photographs shown in appendix IV may give an acceptable impression of the fluctuation over time. Measurements right before (upstream) the weir did not show any fluctuation in water level over a time period of seven hours on 2nd October 2012. 0 0,5 1 1,5 2 2,5 0 20 40 60 80 100 120 Discharge(m3/s) Upstream Guadalete distance (km) Downsteam Side river + 0,3 m3/s WWTP + 0,8 m3/s Weir
  28. 28. 22 Assessment of the ecological state of the Guadalete River, Andalucía, Spain Figure 4.7 Water levels under tidal influence in the Guadalete River (red line) and at the bay of Cádiz (blue line) as a function of time in hours taken on 3 October 2012. This chart shows the possible difference in time between high/low tide at the weir and at the mouth of the river. NOTE: the blue line corresponds with the y-axis, but the red line is only an indication of the tidal difference. The actual height of the tide compared to the one at Cádiz is not known. Do not compare the water levels of the two different lines, only compare the trend. 4.2.3 Total Suspended Solids and Erosion Table 4.1 and the graph in figure 4.8 show the results of the erosion and TSS measurements in the Guadalete River. With the parameters shown in the table it can be determined if there is erosion or not (based on Hulström diagram, refer to figure 4.5). The TSS is also shown in the table, but it has no direct relation to the other parameters. Table 4.1 Overview of results of analyzed parameters that are needed to determine erosion Location Grain size (m) D50 (m) D90 (m) a R Ck Vm (m/s) V (m/s) Erosion TSS (mg/l) 20 0,000315 0,000151 0,0002714 0,28 0,57 79,2 0,272 0,007 No 0,1002 35 0,000004 0,000002 0,0000036 0,12 0,26 106,9 0,018 0,060 Yes 0,2572 30 0,000004 0,000002 0,0000036 0,12 0,50 112,0 0,019 0,178 Yes 0,2572 40 0,000004 0,000002 0,0000036 0,12 0,68 114,4 0,019 0,081 Yes 0,2572 60 0,000004 0,000002 0,0000036 0,12 0,95 117,0 0,020 0,074 Yes 0,5535 100 0,000004 0,000002 0,0000036 0,12 0,68 114,4 0,019 0,166 Yes 0,5815 110 0,000004 0,000002 0,0000036 0,12 0,38 109,8 0,019 0,144 Yes 0,5930 120 0,000004 0,000002 0,0000036 0,12 0,94 116,9 0,020 0,017 No 0,7675 160 0,000004 0,000002 0,0000036 0,12 145 0,000004 0,000002 0,0000036 0,12 150 0,000004 0,000002 0,0000036 0,12 1,24 119,1 0,020 0,007 No 0,5650 0 50 100 150 200 250 300 350 0:00 4:48 9:36 14:24 19:12 0:00 Waterlevel(cm) Time of the day (hours) Waterlevel at Cadiz Waterlevel at weir
  29. 29. 23 Assessment of the ecological state of the Guadalete River, Andalucía, Spain Figure 4.8 Total suspended solids (TSS) in the Guadalete River in mg/L as a function of the distance along the river in kilometers. The x-axis starts at the most upstream sampling point (20), indicated by zero. It ends at the most downstream point at the weir (150). Besides the weir, two other points are indicated in the graph; the addition of water from a side river (Majaceite) and the water of the WWTP of Jerez de la Frontera. The arrow indicates at which point it is located along the Guadalete (it is not a separate sampling point). The polynomial line gives an indication of the trend of the total suspended solids along the river. 4.3 Discussion Cross-section and discharge Because of heavy rainfall (approximately 200 mm) during the week prior to the field days there was more water in the river due to runoff and groundwater extrusion, this may have led to a higher discharge than normal1 . As we expected the discharge increased while we followed the river downstream. The measurements that have been done to construct a cross-section have not been the most accurate because of the fine sediment on the bottom of the river. By measuring the depth of the river by a measuring stick or lead line it was found to be difficult to feel when it touched the upper layer of the bottom. It would have been better to have an application at the end of the measuring stick or on the bottom of the lead line in order to increase the surface so that the stick or the lead would not sink into the bottom. It is estimated that the difference in measured water depth and actual water depth ranges from 0 to 15 centimeter. Since river depth ranges mostly from 0 to 2 meters deep, it is estimated that the error percentage is anywhere up to 7.5%. This estimation is done by looking at the amount of mud on the measuring stick and/or lead thus indicating how deep the stick/lead sunk into the sediment before coming to a stop. According to this, the actual water depth will mostly be lower than then measured water depth. The width of the river is measured fairly accurate. The only factor that might influence this is the slight arch the measuring tape makes when measuring from one bank to another. The accuracy is estimated at 1%, a 10 centimeter possible difference over a 10 meter wide river. It is difficult to estimate the accuracy of the water velocity meter. This is influenced by the moving of the boat (on 1 Heavy rainfall observed by professor Javier Gracia from University of Cadiz 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 0 20 40 60 80 100 120 TSS(mg/l) Upstream Guadalete distance (km) Downsteam Side river WWTP
  30. 30. 24 Assessment of the ecological state of the Guadalete River, Andalucía, Spain which the measuring is done) and possible irregular, or really low water velocities. The accuracy is estimated at 5%. The percentage is this high because of the really low velocities that were measured. The measuring device sometimes wasn’t accurate enough to measure the exact velocity. All of these factors combined give a possible error of 7.5% + 5% + 1% = 13.5%. These percentages are added because the factors are multiplied by each other. This percentage is rather large. However, results show that measurements were fairly accurate. An example of this is the measurements done at two side rivers flowing into one main river. The discharge of the two side rivers combined should be the discharge of the main river. The difference between the measured discharge and the calculated discharge is only 0.6%. Tidal influence As shown in this report the influence of the tide is only reaching to the weir. During the field days the difference in water height at the mouth of the river was approximately 2.65 meter. As results show, there was no change in salinity measured just downstream of the weir during the four hour measurement. A point of discussion is that those samples were taken at the surface of the water. Because the density of salt water is higher than the density of fresh water it is more obviously to find any changes in salinity at the bottom of the river. It would have been better to use a ‘waterhapper’ so it is possible to take water samples from the bottom of the river as well. Total suspended solids and erosion There were several limitations during the course of the work on determining the erosion and suspended solids condition. First of all we were prepared to measure sand particles by means of “sand standard rural”, but it turned out that most of the sampling locations had clay soil for which the our measuring method was useless. Therefore, we assumed the clay particle size from the literature sources. Secondly, the number of the sampling locations in our opinion was not enough for a holistic overview on the erosion situation on the river, nonetheless we determined no erosion downstream opposed to the upstream where the clay particles were small enough to get suspended in the water column. The method of determining the total suspended solids amount also needs mentioning due to a slight inaccuracy in the method. Due to the absence of the needed materials, as such – the drying oven, some adjustments were implemented. The wet weight was not used in for the formula, instead the filters with samples were dried for 24 hours and then measured. 4.4 Conclusion Regarding the quantitative aspects of the river this study has shown that the water that flows from the Guadalete River into the Bay of Cadiz is built up of the discharge from the reservoir near Arcos de la Frontera (0.36 m3 /s), the discharge from the Majaceite River tributary (0.37 m3 /s), the effluent from the relatively large waste water treatment plant of Jerez de la Frontera (variable discharge), and additionally surface runoff water and groundwater (related to precipitation). This adds up to a discharge of 2.0 m3 /s that enters the Bay of Cadiz near El Puerto de Santa Maria. A significant influence on the hydrological aspects of the Guadalete River is formed by the weir, located south of El Portal. Fluctuations in water levels due to high and low tides in the Bay of Cadiz have been observed only downstream of this weir. Upstream of the weir no fluctuations in water levels due to tidal influences have been observed. This weir was constructed to prevent salt water intrusion in agricultural fields upstream and based on our observations salt water does not intrude
  31. 31. 25 Assessment of the ecological state of the Guadalete River, Andalucía, Spain the upstream parts of the Guadalete River indeed. The weir seems to function according to its purpose. Due to surface runoff in rural and urban areas during rainy periods the amount of TSS in the river seems to increase (built up) towards the mouth of the river. The tributary Majaceite River brings water with a lower amount of TSS into the Guadalete River, It is also clear that the waste water treatment plant of Jerez de la Frontera delivers water with a lower amount of TSS to the river. The water quality of the Guadalete River is expected to be influenced by suspended solids. A high amount of TSS means higher turbidity which again leads to less photosynthetic activity by aquatic plants and algae and therefore less production of oxygen. Our results show an increase of TSS towards the mouth of the river, while looking at the results of oxygen measurements (see chapter 6) we see a corresponding decrease of dissolved oxygen concentration. This suggests there is a solid link between the TSS, turbidity, and photosynthetic activity. In the upper part of the river the velocity was higher than in the lower part of the river as expected in a normal river system. However, the velocity in the lower part of the river – influenced by the weir – was relatively low. According to the Hulström diagram this would mean that sedimentation is taking place in this area. Erosion of sediments, therefore, takes place in the upper part of the river where the velocity is higher.
  32. 32. 26 Assessment of the ecological state of the Guadalete River, Andalucía, Spain 5. Chemistry The chemical aspects of the river were investigated in a stretch of approximately 170 km running from the dam of the reservoir near Arcos de la Frontera till the mouth of the river in the Bay of Cadiz (see figure 5.1). In this chapter the chemical aspects of the influences from the waste water treatment plant of Jerez de la Frontera, agriculture, tributaries, and tidal influences are described in terms of methods, results, discussion and conclusion. Sampling point code: 10 20 30 40 50 60 100 110 120 130 140 150 160 170 180 Distance from starting point (km): 0 6 23 24 34 39 56 67 73 75 84 86 92 99 107 Figure 5.1 Map of Guadalete River with sampling points for chemical measurements 5.1 Method and Materials 5.1.1 Field Measurements The parameters in the field were measured just below the surface of the water. When it was not possible to measure directly in the water, samples were taken with a bucket. Dissolved oxygen concentration, oxygen saturation level, pH, salinity, and temperature were measured in the field. Salinity, conductivity and temperature Salinity and conductivity were measured with a digital conductivity-meter (type: WTW LF 330). The conductivity-meter measures the amount of salt in the water in g/L or conductivity in µS/cm. The temperature (in °C) was also measured with this meter. Oxygen Dissolved oxygen concentration and oxygen saturation level were measured with a digital oxygen- meter (type: WTW Oxi 330). The oxygen meter measures the concentration of dissolved oxygen in the water in mg/L and the oxygen saturation level in percentage of saturation.
  33. 33. 27 Assessment of the ecological state of the Guadalete River, Andalucía, Spain pH The pH was measured with digital pH-meter (type: WTW 340). The pH-meter measures the acidity and the amount of free hydrogen ions in the water. 5.1.2 Laboratory Measurements At each sampling point a water sample from just below the water surface was collected. These samples were analyzed in a temporary field laboratory. Concentrations of the following chemical substances in the water samples were determined with a photo-spectrometer or Lasa 20 and the Hach-kit (Hach/Dr 2400, see figure 5.2): • Ammonium (NH 4 + - N) • Nitrite (NO2 - - N) • Nitrate (NO 3 - - N) • Phosphate (PO 4 3- - P) • Dissolved Inorganic Nitrogen (DIN) Analyses of chemical substances were performed according to the ‘Hach Company – manual’ Figure 5.2 The Hach-kit used by measuring the chemical parameters 5.2 Results In this paragraph the results of the field- and laboratory measurements are presented in the form of graphs which visualize the value of each parameter over the course of the river from the starting point near Arcos de la Frontera towards the mouth of the river near El Puerto de Santa Maria. Raw data of all measurements can be found in appendix V. 5.2.1 Field Measurements Salinity In the distance between 0 and 120 kilometres from Arcos de la Frontera no significant dissolved salt content was observed (see figure 5.3). This can be explained by the presence of a weir (refer to chapter 4) at around 120 kilometres which blocks saline water. Downstream of the weir the salinity
  34. 34. 28 Assessment of the ecological state of the Guadalete River, Andalucía, Spain increases due to the tidal influence. Figure 5.3 Salinity (g/L) measured in the Guadalete River Temperature The temperature in over the course of the Guadalete River (see figure 5.4) is relatively constant. At the starting point the temperature is slightly higher. The temperature also rises a little in the lower reaches, presumably due to mixing with sea water that has a higher temperature. Figure 5.4 Temperature (°C) measured in the Guadalete River Oxygen The red line at 5 mg/l in the graph of dissolved oxygen concentration in figure 5.5 represents a standard for the minimum dissolved oxygen concentration that is required for healthy water. 0 5 10 15 20 25 30 0 20 40 60 80 100 120 140 Salinity(g/l) Distance (km) Salinity Salinity 0 5 10 15 20 25 30 0 20 40 60 80 100 120 140 Temperature(°C) Distance (km) Temperature temperature
  35. 35. 29 Assessment of the ecological state of the Guadalete River, Andalucía, Spain At the beginning of the measured stretch of the Guadalete River (starting at 0 km) a very low concentration of dissolved oxygen was observed. Presumably this is caused by the water that was measured derived from the hypolimnion of the reservoir near Arcos de la Frontera. The hypolimnion is that part of the water column that is isolated from surface wind and usually receives insufficient irradiance (light) for photosynthesis to occur as a result of stratification. Figure 5.5 Dissolved oxygen concentration (mg/L) measured in the Guadalete River Further downstream (at 22.5 km) the oxygen concentration is above 5 mg/L. Most likely this is caused by the current, rock and small waterfalls present in this part of the river causing more oxygen to dissolve from the atmosphere into the water. The concentration decreases at around 90 kilometres from the Arcos de la Frontera and even further at 100 kilometres. At these points a small stream deriving from the suburban and rural areas and the effluent of the waste water treatment plant enters the Guadalete River respectively. Both point sources are suspect to discharge nutrient rich water (see also upcoming results of DIN, nitrate and phosphate) in the river which results in an increase in oxygen demand by bacteria that decompose these nutrients. pH The graph of the pH (see figure 5.6) confirms the dissolved oxygen concentration in figure 5.5. At first the pH is low because the water comes from the hypolimnion part of the reservoir near Arcos de la Frontera. However, it changes in the course of the Guadalete River. Between the distance of 90 and 100 km from the starting point there is a drop of in the pH. The water becomes more acidic due to the low oxygen concentrations as shown in figure 5.5. The carbon dioxide rises at those two points. 0 1 2 3 4 5 6 7 8 9 0 20 40 60 80 100 120 140 Oxygen(mg/l) Distance (km) Oxygen Oxygen Standard
  36. 36. 30 Assessment of the ecological state of the Guadalete River, Andalucía, Spain Figure 5.6 PH measured in the Guadalete River When the amount of carbon dioxide (CO2) in the water increases, the pH decreases. Carbon dioxide dissolves slightly in water to form a weak acid called carbonic acid (H2CO3) according to the following reaction: CO2 + H2O H2CO3 After that, carbonic acid reacts slightly and reversibly in water to form a hydronium cation, H3O+ , and the bicarbonate ion, HCO3 - , according to the following reaction: H2CO3 + H2O HCO3 - + H3O+ 5.2.2 Laboratory Measurements Ammonium The graph in figure 5.7 shows two clear peaks of ammonium concentration in the Guadalete River. Keeping in mind the earlier explanation of dissolved oxygen concentration (figure 5.5) the peak of ammonium concentration near the reservoir of Arcos de la Frontera can be explained by stratification as well. The hypolimnion has a low oxygen concentration, and therefore there is no or very few oxygen available for the nitrification process that normally converts ammonium into nitrate via nitrite. 6,8 7 7,2 7,4 7,6 7,8 8 8,2 8,4 0 20 40 60 80 100 120 140 pH Distance (km) pH pH
  37. 37. 31 Assessment of the ecological state of the Guadalete River, Andalucía, Spain Figure 5.7 Ammonium (mg/l) measured in the Guadalete River At around a distance of 100 kilometres the waste water treatment plant of Jerez de la Frontera causes a second peak of ammonium in the investigated stretch of the Guadalete River. Apparently the effluent of the waste water treatment plant contains a high concentration of ammonium that is further downstream rapidly converted into nitrate via nitrite. Nitrite A peak in nitrite concentration (see figure 5.8) was observed at a short distance (5 km) from the reservoir near Arcos de la Frontera. The concentration of nitrite is expected to increase in accordance to a decrease of ammonium. Both results comply with this theory based on the process of nitrification; ammonium is converted into nitrite. Moreover, this theory is reinforced by the drop of concentration of dissolved oxygen in this part of the river; oxygen is required in the nitrification process. At a distance of about 102 km there is a little drop in nitrite concentration. This can be explained by the high concentration of ammonium (figure 5.7) due to discharge of effluent from the waste water treatment plant of Jerez de la Frontera. The concentration of ammonium is higher; therefore the oxygen concentration is lower which results in a lower concentration of nitrite. 0 1 2 3 4 5 6 7 8 0 20 40 60 80 100 120 140 NH4 +-N(mg/l) Distance (km) NH4+-N NH4+-N
  38. 38. 32 Assessment of the ecological state of the Guadalete River, Andalucía, Spain Figure 5.8 Nitrite (mg/L) measured in the Guadalete River Nitrate The next step in the nitrification process is the conversion of nitrite into nitrate. The results of the measurements on nitrate (see figure 5.9) are comparable to the results of nitrite (figure 5.8). The increase at 83 km is not clear, but this can probably explained by the influence of agriculture on the water quality. Figure 5.9 Nitrate (mg/L) measured in the Guadalete River Phosphate The red line at 0.15 mg/l in the graph of the concentration of ortho-phosphate as P in figure 5.10 represents a standard for the maximum concentration of Ptot that is allowed for healthy water. At the distance were the waste water treatment plant of Jerez de la Frontera is located the concentration of ortho-phosphate was extremely high compared to the other sampling points and the maximum allowable concentration. The reason for the high value at the beginning of the stretch is most likely due to the high phosphate concentration in the hypolimnion of the reservoir as well. 0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0 20 40 60 80 100 120 140 NO2 --N(mg/l) Distance (km) NO2- N NO2- N 0 0,5 1 1,5 2 2,5 3 0 20 40 60 80 100 120 140 NO3 --N(mg/l) Distance (km) NO3- -N NO3- -N
  39. 39. 33 Assessment of the ecological state of the Guadalete River, Andalucía, Spain Figure 5.10 Ortho-phosphate as P (mg/L) measured in the Guadalete River Dissolved Inorganic Nitrogen (DIN) The red line at 2.2 mg/l in the graph of the concentration of DIN in figure 5.11 represents a standard for the maximum concentration of Ntot that is allowed for healthy water. Ammonium (NH4 + ), nitrite (NO2 – ) and nitrate (NO3 – ) are the most common ionic (reactive) forms of dissolved inorganic nitrogen in aquatic ecosystems. These ions can be present naturally as a result of atmospheric deposition, surface and groundwater runoff. Between 89 km and 91 km there is a side stream with many nutrients coming in from Jerez de la Frontera. Before 102 km there is a wastewater treatment plant; the concentration is very high after this plant. Figure 5.11 Dissolved inorganic nitrogen (DIN) (mg/L) measured in the Guadalete River The high concentration of DIN could have major environmental problems to aquatic ecosystems: 0,000 0,200 0,400 0,600 0,800 1,000 1,200 1,400 1,600 1,800 0 20 40 60 80 100 120 140 PO4 3--P[mg/l] Distance (km) PO4 3- -P Ortho phosphate as P P total standard 0,00 1,00 2,00 3,00 4,00 5,00 6,00 7,00 8,00 9,00 0 20 40 60 80 100 120 140 Dissolvedinorganixnitrogen[mg/l] distance (km) Dissolved inorganic nitrogen DIN N total standard
  40. 40. 34 Assessment of the ecological state of the Guadalete River, Andalucía, Spain 1. It can increase the concentration of hydrogen ions in fresh water ecosystems without much acid-neutralizing capacity, resulting in acidification of those ecological systems; 2. It can stimulate or enhance the development, maintenance and proliferation of primary producers, resulting in eutrophication of estuarine, and coastal marine ecosystems. In some cases, in organic nitrogen pollution can also induce the occurrence of toxic algae; 3. It can impair the ability of aquatic animals to survive, grow and reproduce as a result of direct toxicity of ammonia, nitrite and nitrate. In addition, inorganic nitrogen pollution of ground and surface water could induce adverse effects on human health.2 5.3 Discussion It should be clear that the results as shown in this chapter are based on measurements that were conducted in only two field days, meaning that it is just a ‘snapshot’ of what the real situation over a longer period of time would be. The significantly high concentrations of nutrients near the dam of Arcos de la Frontera could be explained by the fact that when the water rushes from the dam sediments with a high abundance of nutrients will be mixed with the river’s water. Therefore, the concentrations of nitrogen and phosphorus containing substances may be high. However, nitrogen concentrations are believed not be high enough to form a direct threat to the survival of aquatic organisms. As stated in the results, stratification in the reservoir near Arcos de la Frontera most likely has played an important role in the chemical state of the river. However, this phenomenon has not been measured during this study. For future research measuring the stratification in this reservoir would be highly recommended in order to reinforce theories about the chemical state of the Guadalete River. 5.4 Conclusion WWTP effluent The results of the chemical analysis of the Guadalete River show that the waste water treatment plant of Jerez de la Frontera most likely has a big impact on the chemical state. This is especially noticeable when looking at the oxygen concentration before and after the point where effluent of the plant is discharged; right after this point a clear oxygen sag curve is shown and the oxygen concentration decreases even below 3 mg/L, while the standard for oxygen is 5 mg/L. Also the pH is decreasing at the point where the effluent is discharged. Concentrations of nutrients (e.g. DIN, ammonium, and phosphate) show a peak right after the waste water treatment plant. We assume that these nutrients – and corresponding effects on oxygen concentration and acidity – derived from the effluent of the waste water treatment plant of Jerez de la Frontera. Agriculture Presumably agriculture in the region of the Guadalete River has little impact on the chemical state of the river. When looking at the results of oxygen measurements, a small decrease in the concentration is shown between the junction of the Guadalete River and the Majaceite River, and at the location right before the discharge point of the waste water treatment plant. Therefore, 2 http://www.eoearth.org/article/Inorganic_nitrogen_pollution_in_aquatic_ecosystems:_causes_and_consequences
  41. 41. 35 Assessment of the ecological state of the Guadalete River, Andalucía, Spain agriculture has relatively low impact on the chemical state and in particular on the oxygen concentration of the Guadalete River. Although, it is unknown what the influence of the usage of fertilizers is on the nutrient concentration in the river. Tributaries Our results indicate that there is in general not much influence of (natural) tributaries on the Guadalete River. Tidal influence Clear results of measurements of salinity indicate that the tide has no influence on the Guadalete River that lies upstream of the weir (104 km downstream of the reservoir near Arcos de la Frontera). The downstream part of the river, after the weir, is highly influenced by the salt water from the Bay of Cadiz. Overall chemical water quality The chemical water quality is not good. But the measured parameters vary significantly at the different parts of the river. At the first 5 km from the dam the water quality is bad, due to the bad quality of the inflowing water from the hypolimnion of the reservoir at Arcos de la Frontera (caused by stratification in the reservoir). But the quality improves rapidly, probably due to vegetation and less pollution in the water. Until 20 km from the dam, the water quality has reached its peak and is slowly decreasing. This is probably due the surrounding agriculture and its leaking groundwater into the river. 80 km downstream a polluted stream from Jerez de la Frontera is flowing into the river. This is causing a faster decrease in the water quality than the agriculture did. But the most rapid decrease in the river appears when the effluent of the WWTP flows into the river. An oxygen sag curve is shown in figure 5.5. This indicates a very bad water quality right after the WWTP effluent entered the river. After the weir the water quality is slowly improving, but stays under the European standard. So, overall the chemical water quality of the river the Guadalete is mediocre to poor.
  42. 42. 36 Assessment of the ecological state of the Guadalete River, Andalucía, Spain 6. Biology The biological aspects of the river were investigated in a stretch of approximately 170 km running from the dam of the reservoir near Arcos de la Frontera till the mouth of the river in the Bay of Cadiz (see figure 6.1). In this chapter the biological aspects of the influences from the waste water treatment plant of Jerez de la Frontera, tributaries, and tidal influences are described in terms of methods, results, discussion and conclusion. Sampling point code: 10 20 30 40 50 60 100 110 120 130 140 150 160 170 180 Distance from starting point (km): 0 6 23 24 34 39 56 67 73 75 84 86 92 99 107 Figure 6.1 Map of Guadalete River with sampling points for measuring the biological water quality 6.1 Method and Materials 6.1.1 Macrofauna Sampling Preconditions measuring area The measuring are was indicated in advance of the actual sampling itself. The first step was to look for background information regarding the measuring points, to get a good impression of the locations. The measuring points were chosen in such a way, that they represent the larger water body and its habitats. Sampling points where human intervention had recently taken place were avoided, unless the human interventions represented the total water basin. The measuring area chosen had an approximate length of 100 meters, with all the measuring points located in this stretch. It was of the utmost importance to try and find sampling points which were submerged for the previous two months, this was checked by looking for algae and snails on any possible available stones (see figure 6.2).
  43. 43. 37 Assessment of the ecological state of the Guadalete River, Andalucía, Spain Habitat localization It was of great importance to distinct all the relevant habitats within the measuring area, for the macrofauna. In order to look for the different habitats, special attention was paid on the following things: Table 6.1 Habitats and characteristics Substrate Consistency, structure and general state Vegetation Structure and biodiversity Shore Shape and vegetation Discharge Fluctuation in discharges Positioning of the watercourse Positioning of the sun, wind, shade and water-depth Once the habitats were located and determined, the habitat type and the correlated endeavor were determined. If the habitat seemed low in biodiversity, the sampling endeavor was great, to make sure all the possible species would be sampled. There was looked for signs of the quantity of species, and the endeavor of sampling was adjusted according to it. The more heterogeneous the habitat was the more endeavor was required, the more homogeneous the habitat was, the less endeavor was required. In general the required sample length made with the macrofauna net was around 5 meters, but could be increased to 10 meters once the habitat was determined to be very heterogeneous. Figure 6.2 Example of sampling area with a variation of habitats as shown here in a tributary of the Guadalete River Sampling technique Before starting sampling, the net was checked for possible damages. The net was checked for if it was clean before applying to a new habitat, in order to make sure no organisms from a previous
  44. 44. 38 Assessment of the ecological state of the Guadalete River, Andalucía, Spain habitat were left behind. Sampling from the shore is preferred above sampling from the shore (Werkvoorschrift 12A Bemonstering van macrofauna). Once approaching the actual sampling point, great attention was paid in order to prevent disturbance of the habitat, by approaching towards the sun, in order to prevent shadow casting. The net was moved through the water, soil and vegetation in a jerky way. This was done with a speed which made it impossible for macrofauna to escape from the net. Once in flowing water, the movement direction was made opposite of the flow, in stagnant water, a movement was made first and directly after that, another movement opposite of the first, to trap any potential remainders. The net was checked regularly and emptied, to prevent clogging and losing of macrofauna. This technique was applied to the soil, water column, submerged vegetation and emerged vegetation. Once this technique was applied to the soil, the kicking technique was implemented as well, to stir up soil and the macrofauna inside it Sample sorting and preservation Once the samples were taken according to the above mentioned techniques, they were placed in white photo-trays and sorted and identified at site. Sorting and identifying was done at site to prevent killing of macrofauna between one another, and guarantee the preservation of macrofauna which was rare. Fragile animals and predators were placed in separate jars. The jars were next labeled according to the measurement point. Ethanol of 96% was added to the samples to kill the macrofauna immediately. For the used literature see ‘Biology’ in Chapter 10 Literature. 6.1.2 Macrophyte Sampling Only vegetation which was at least partially in the water or influenced by the water was taken into account. The locations where measurements were taken were determined by accessibility. All the possible parts of the river with different characteristics were sampled. At the different locations a section of a hundred meters was chosen from where species were sampled. These sections had to be a least ten meters from disturbing factors like bridges, weirs and dams. The species which were recognized at site were to be filled in on the field sheet. Species which were not known, samples were taken back to the lab. If possible, the whole plant was taken (including leafs, stems, flowers and roots) back to the lab. Found species were described with (Latin) names, percentage of the total vegetation and as a percentage of which past was (partially) submerged and which part grew at the shore. 6.1.3 Biotic Index The Biotic Index (BI) is used in many European countries as a standard method for water quality assessment of running water (rivers and streams), which uses indicator species to determine the water quality. If a ‘sensitive’ species is found, it can be said that the water where it was found, has a good quality. The BI has a range from 1 to 10, meaning that 1 is very bad and 10 is very good. A quality of 5 to 6 indicates a moderate quality, but also critical state, since a quality of 3 to 4 is already a bad quality. The value for biotic index is calculated based on the presence of so called indicator species. An indicator species or biological indicators are used to monitor the health of an ecosystem. In the field, as much indicator species as possible are collected to make sure the biotic index is reliable. In table 6.2 is shown how the Biotic Index can be calculated. In the horizontal row the total taxa are found. These are subdivided into classes. This is the easiest way to make clear the diversity in the water. The biotic index is determined by the intersection of the row corresponding to the most
  45. 45. 39 Assessment of the ecological state of the Guadalete River, Andalucía, Spain sensitive indicator group that is present in a sample of the column corresponding to the total number of observed taxa of the same steel. Table 6.2 ‘Scorecard’ for determination of the Biotic Index Not all macroinvertebrates that can be found are listed in the biotic index. The reason is that the do not rely on oxygen within the water for survival. For those macroinvertebrates that do rely on oxygen in the water, some can only live in water that has a lot of oxygen and vice versa. Generally if the water is more polluted there is less oxygen dissolved in the water. The categories ascribe different numerical values to the organisms. On a worksheet the value from that category combined with the amount of individuals of that species found gives a final value which determines the condition of the water quality. 6.1.4 Ecological Quality Ratio For a review of the ecological condition of the Guadalete River according to modern European standards the methodology of the European Water Framework Directive (EWFD) is applied in this study. The ecological condition of a water body in this method is expressed as the Ecological Quality Ratio (EQR) and ranges from 0 to 1. Therefore there is a list with characteristic, positive and negative taxa. The EWFD has yardsticks. By putting the found indicator species for characteristic, negative and positive taxa in equation (E6.1) the ecological condition of the Guadalete River can be determined. In this case the Dutch methodology is used. Every European member state has its own assessment method and equation. EQR = { 200*(KM%/KMmax) + 2*(100-DN%) + (KM%+DP%) }/500 (E6.1) 0-1 2-5 6-10 11-15 > 16 Pleceoptera > 2 - 7 8 9 10 Heptageniidae 1 5 6 7 8 9 2 Trichoptera > 2 - 6 7 8 9 Ancylidae 1 5 5 6 7 8 Ephemeroptera 1-2 3 4 5 6 7 Aphelocheirus > 1 3 4 5 6 7 Odonata Gammaridae Mollusca Asellidae > 1 2 3 4 5 - Hirudinea Sphaeriidae Hemiptera Tubificidae > 1 1 2 3 - - Chironomus thummi-plumosus 7 Syrphidae- Eristalinae > 1 0 1 1 - - 6 5 4 3 1 TaxaClass frequency Indicator groups Tolerance class
  46. 46. 40 Assessment of the ecological state of the Guadalete River, Andalucía, Spain Where: - DN% (abundance): percentage of negative dominant indicators - KM% (quantity taxa): percentage of characteristic taxa - KM% + DP % (abundance): percentage of positive dominant indicators The Guadalete River is compared with a R6 water type; slowly flowing river on sand and or clay. Sampling point 32 is classified as a R16-type; fast flowing river on sand or clay. The mouth of the river, sampling point 170, is a C2-type; estuary with a moderate tidal rate. According to the EWFD a water body should be compared to a reference. ‘REFCOND Guidance 2003’ prescribes that the reference water and a ‘very good ecological condition’ is set equal to each other. 6.2 Results In this chapter for each sampling point the status of macrofauna and macrophytes is reviewed. The sampling points will be compared with the biological index and the Dutch methodology of European Water Framework Directive (EWFD). 6.2.1 Biotic Index Based on the found macrofauna taxa (see figure 6.3) the Biotic Index of the different sampling points has been determined and shown in table 6.3. Sampling points 20, 32 and 40 have a Biotic Index of 6 and 5 and 5 respectively, which indicates a moderate water quality. At sampling points 135 and 150 no indicator species have been found during the research. Points 158 and 170 turned out to be brackish water and therefore no Biotic Index has been determined since this method only applies to freshwater systems. Full list of the identified macrofauna organisms at all sampling points can be found in appendix VI. Figure 6.3 Macrofauna of the Guadalete (selection): (A) Ephemeroptera; Caenis spec., (B) Odonata; Ophiogomphus serpentinus, (C) Odonata; Cercion linden, and (D) Trichoptera; Polycentropodidae (Family). Table 6.3 Overview of found indicator groups and Biotic Index per sampling point Sampling point Indicator groups Taxa found Biotic Index 20 Ephemeroptera 11 6 32 Odonata 6 5 40 Trichoptera 3 5 135 none - - 150 none - - 158 n/a n/a n/a 170 n/a n/a n/a

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