Rio Candelaria Integrated Watershed Management Plan
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Rio Candelaria Integrated Watershed Management Plan

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The purpose of the watershed management plan for the Rio Candelaria watershed is to investigate the major factors causing environment degradation. Anthropogenic activities including deforestation will ...

The purpose of the watershed management plan for the Rio Candelaria watershed is to investigate the major factors causing environment degradation. Anthropogenic activities including deforestation will be assessed to determine the impact of these actions on ecosystem integrity. The integrated watershed management plan will suggest possible sustainable land use and management strategies of land and water resources to help remediate and mitigate environmental degradation in the Candelaria watershed area.

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Rio Candelaria Integrated Watershed Management Plan Rio Candelaria Integrated Watershed Management Plan Document Transcript

  • Integrated Watershed Management Plan for Rio Candelaria To: Dr. Raul Ponce Written By: Amber Brant Denika Piggott Reesha Petal Wabel Irshaidat Date: April 28, 2010
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico Table of Contents 1.0 INTRODUCTION…………………………………………………………………………… 1.1 BACKGROUND INFORMATION………………………………………………………… 1.2 GEOGRAPHICAL AREA………………………………………………………………... 1.3 PURPOSE………………………………………………………………………………. 1.4 OBJECTIVES……………………………………………………………………………. 2.0 WATERSHED DELINEATION……………………………………………………………. 2.1 OBJECTIVES……………………………………………………………………………. 2.2 HYDROLOGICAL NETWORK……………………………………………………………. 2.3 WATERSHED BOUNDARIES…………………………………………………………….. 2.3.1 Main Watershed Boundary……………………………………………………. 2.3.2 Sub-watershed Boundaries……………………………………………………. 2.4 STREAM MORPHOMETRY………………………………………………………………. 2.5 HYDROLOGICAL PARAMETERS………………………………………………………… 2.6 PHYSICAL CHARACTERIZATION OF THE WATERSHED…………………………………. 3.0 CLIMATIC INVENTORY………………………………………………………………….. 3.1 Objectives……………………………………………………………………………… 3.2 Data Collection from Meteorological Stations in Area………………………………… 3.3 Evapotranspiration (ETo) Estimation……………………………………………………. 3.4 Length-of-growing-period (LGP) Estimation………………………………………….. 3.5 Climograph Data………………………………………………………………………… 3.6 Soil Moisture and Climate Type of Candelaria Watershed……………………………. 4.0 ECOLOGICAL ZONES……………………………………………………………………. 4.1 PROCEDURE……………………………………………………………………………. 4.2 LAND FACETS…………………………………………………………………………. 4.3 ZONING……………………………………………………………………………….. 5.0 SURFACE RUNOFF ESTIMATION………………………………………………………... 5.1 OBJECTIVE………………………………………………………………………………. 5.2 INTENSITY- DURATION-FREQUENCY CURVES (IDF)…………………………………….. 5.3 CONCENTRATION TIME (TC)…………………………………………………………….. 5.4 RAINFALL INTENSITY (I)…………………………………………………………………. 5.5 RUNOFF COEFFICIENT (C)………………………………………………………………... 5.6 AREA OF SUB-WATERSHEDS (A)………………………………………………………….. 5.7 CALCULATION OF MAXIMUM RUNOFF (Q)………………………………………………. 5.8 AVERAGE PRECIPITATION (PM)………………………………………………………….. 5.9 CALCULATION OF AVERAGE RUNOFF (VM)……………………………………………… 5.10 RESULTS ………………………………………………………………………………… 6.0 LAND USE INVENTORY………………………………………………………………….. 6.1 OBJECTIVES…………………………………………………………………………. 6.2 PROCESS……………………………………………………………………………. 6.3 RESULTS……………………………………………………………………………. Page │ 2
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico 7.0 LAND CAPABILITY ASSESSMENT……………………………………………………. 7.1 PURPOSE AND PROCEDURES…………………………………………………………… 7.2 RESULTS……………………………………………………………………………. 7.3 CANDELARIA WATERSHED “HOT SPOTS” …………………………………………… 8.0 LAND SUITABILITY ASSESSMENT……………………………………………………. 8.1 PURPOSE AND PROCEDURES…………………………………………………………… 8.2 CLIMATIC AND SOIL REQUIREMENTS OF THE CROPS…………………………………… 8.2.1 Banana………………………………………………………………………… 8.2.2 Coconut………………………………………………………………………… 8.2.3 Dry beans………………………………………………………………………… 8.2.4 Maize………………………………………………………………………… 8.2.5 Rice………………………………………………………………………… 8.2.6 Sorghum………………………………………………………………………… 8.2.7 Squash………………………………………………………………………… 8.2.8 Sugar cane………………………………………………………………… 8.2.9 African Stargrass………………………………………………………………… 8.3 RESULTS……………………………………………………………………………… 9.0 LAND DEGRADATION ASSESSMENT………………………………………………….. 9.1 Remote Sensing Applications…………………………………………………………. 10.0 CONCLUSIONS……………………………………………………………………………… 11.0 RECOMMENDATIONS…………………………………………………………………….. 12.0 REFERENCES………………………………………………………………………………. Page │ 3
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico List of Figures Page │ 4
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico List of Tables Page │ 5
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico 1.0 INTRODUCTION 1.1 BACKGROUND INFORMATION The ancient Maya occupied the Yucatan Landscape from 3000 to 1100 years ago. At the height of their civilization, the Maya had their largest population within the Candelaria region. The Candelaria watershed is one of the few rivers flowing through the highly karstic region of the Yucatan Peninsula (Benke & Cushing, 2005). This is the most probable rationale behind why the ancient Mayan civilization developed in this area. The ancient Maya developed and practiced diverse and sophisticated agricultural food production methods. The traditional slash-and-burn agriculture techniques are believed to be developed by the ancient Mayan populations. Mayan farmers incorporated many other management techniques into their agricultural practices including permanent raised fields, terracing, forest gardens, managed fallows, and wild harvesting. Slash-and-burn agriculture along with the management techniques were crucial to support the large populations in the Mayan civilization. There is some evidence of these different systems that persist today. There are some areas that have raised fields connected by canals that can be seen on aerial photographs. Furthermore, current rainforest species composition in the area contains significantly higher abundance of species of economic value to ancient Maya (NJK, 2006). The superficial landscape processes in the Candelaria watershed have been anthropogenically modified for several thousand years due to the occupation of the ancient Mayan population. The significant anthropogenic landscape disturbance and river modification was caused by forest clearing associated with slashand-burn agriculture. Landscape modification was also caused by water surface hydrology exploitation for agriculture. This was necessary because the permeable and fractured limestone caused the water table in most areas to be located 100m beneath the surface. The impact of these activities has resulted in an increase in soil erosion and lake-wetland sedimentation (Benke & Cushing, 2005). During the 3000-year occupation of the ancient Mayan civilization, enormous tracts of forests were cleared. The Mayan empire collapsed roughly 1100 years ago, leaving the landscape of the Candelaria watershed to re-establish. Most of the existing landscape does not pre-date the Maya collapse which is why there is considerable debate regarding the degree to which this landscape is “natural”. Since the collapse of the Mayan empire, there has been very little development in this area other than the traditional slash-and-burn agriculture and non-destructive forestry extraction. The traditional agricultural practice of slash-and-burn is currently still practiced by Mayan farmers in the Candelaria watershed area. However, these systems have been altered with changing population pressures, Page │ 6
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico cultures, economic systems, climate change, and the availability of synthetic fertilizers and pesticides (NJK, 2006). The traditional slash-and-burn technique was developed by the Mayan community to increase fertility of the soil. In the pre-Hispanic period, traditional slash-and-burn agriculture provided the soil with nutrients by the addition of ash from the burning process and involved a 50-year fallow period. This 50-year fallow period allowed for up to 7 or 8 years of continuous cropping before the nutrients in the soils would be exhausted and farmer had to shift to another plot of land. However, due to population increase which has resulted in a greater stress on farmers, these fallows periods have decreases significantly to 7 years allowing for only 2 years of continuous cropping and decreases in crop biomass and yields (Ponce, 2010). In the 1960’s, population density began to increase rapidly bringing a renewed deforestation from largescale logging operations and rapid population growth. Forest clearing has also occurred for the creation of cattle grazing land. These land use changes are likely causing increased runoff and storm flow into the Rio Candelaria stream network. There is very little industry or commercial activities in the Candelaria watershed with the only significant urban area being the city of Candelaria located near the mouth of the river (Benke & Cushing, 2005). The Terminos Lagoon and the municipality of Carmen was an important trade center and military outpost for the Mayans and Chontals before the colonial period began and the area became an important center for British, Scottish and Irish pirates around 1558 (Robadue et al. 2004). Three boom and bust periods characterize the area’s economic history and relationship between the population and its resources. The first commercialized natural resource mentioned here is the “palo de tinte” thorny tree (Haematoxullum campechianum), which was logged for its hematoxylin, a naturally colouring agent that could be exported as ink (Robadue et al. 2004). The tree grows in very clayey soils that are subject to flooding, so the watershed surrounding the Lagoon was logged (Robadue et al. 2004). The commercialized use of this tree began at the start of the colonial period and ended just after the beginning of the 20th century when hematoxylin was commercially undermined by Europe’s aniline dyes (Robadue et al. 2004). From 1900-1940, there was no commercially important economic activity taking place in the region, leading to a period of economic decline (Robadue et al. 2004). The era of shrimp fisheries in the Terminos Lagoon region began in 1940 where an economic boom began with the discovery of new shrimp species like the white, brown and the "camaron gigante" shrimp (Robadue et al. 2004). During this period, land was cleared in the surrounding watersheds to plant coconut palm, which is a resource that eventually failed commercially, but altered the landscape nonetheless (Robadue et al. 2004). The petroleum development era began in 1970 when Petroleros Mexicanas (PEMEX) was established as an enterprise to extract, market and export oil (Robadue et al. 2004). This economic boom, resulted in increased urbanization in Ciudad de Carmen, located on the Isla del Carmen that divides the Gulf of Mexico Page │ 7
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico with the Terminos Lagoon (Robadue et al. 2004). Environmental and social concerns and conflicts led to the declaration of the 705,016-ha Terminos Lagoon reserve area in 1994 (Robadue et al. 2004). The oil and gas supplies are expected to expire within the next two to three decades, resulting in another economic shift in the area (Robadue et al. 2004). Environmental concerns in the Terminos Lagoon include oil spills from offshore wells, inadequate treatment of wastewater in the city of Carmen, and illegal fishing in the reserve areas (Robadue et al. 2004). Mangroves are especially affected by increased sedimentation into the Lagoon as well as fragmentation caused by decreased water flow by highways and other debris like fishing gear, which effectively cuts off their water circulation cycle and leads to further shore erosion (Robadue et al. 2004). 1.2 GEOGRAPHICAL AREA The Rio Candelaria watershed basin flows through two major physical provinces in Mexico, the Yucatan (YU) and the Mexican Golf Coastal Plain (CP). This area is located within the state of Campeche, Mexico. The Rio Candelaria basin has an approximant land area of 5670 km2 (56700ha) covering three municipalities. The municipality of Candelaria is the central area of the watershed basin. The municipality of Carmen is located at the mouth of the river where it discharges in the Laguna de Terminos. To the north, a small portion of the watershed boundaries enter the municipality of Escarcega. Most of the Candelaria watershed is located in Mexico, however 50 km of channel extends into the Petén of northern Guatemala that covers an approximately area of 715 km2. The watershed area covers the UTM coordinates 670000mE to790000mE and 1950000mN to 206000mN. Below is a figure of the location of the Candelaria watershed within the country of Mexico. Page │ 8
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico State of Campeche Gulf of Mexico 5 Champoton Carmen Escarcega Candelaria State of Tabasco GUATEMALA 0 20,000 40,000 60,000 Meters Figure 1.1: Location of the Candelaria Watershed in reference to the state of Chempeche, Mexico 1.3 PURPOSE The purpose of the watershed management plan for the Rio Candelaria watershed is to investigate the major factors causing environment degradation. Anthropogenic activities including deforestation will be assessed to determine the impact of these actions on ecosystem integrity. The integrated watershed management plan will suggest possible sustainable land use and management strategies of land and water resources to help remediate and mitigate environmental degradation in the Candelaria watershed area. 1.4 OBJECTIVES The main objective of this integrated watershed management plan is to investigate the Candelaria watershed and create a plan that assesses resource allocation and recommends potential interventions. A breakdown summary of the objectives involved in the integrated watershed management plan for the Candelaria watershed is as follows: • Characterize and delineate the Candelaria watershed into ArcGIS • Compile point elevations to create digital elevation model • Breakdown of the watershed area into Land Systems followed by Land Facets • Compile climatic inventory to derive length of growing period (LGP) for the watershed • Identify and map Ecological Zones (EcoZones) using Land Facets and LGP • Compile current and possible land utilization types of the watershed area • Assess watershed land capability Page │ 9
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico • Diagnosis and determine of the watershed “Hot Spots” • Analysis land suitability of suggested LUTs in agreement with the land capability classes • Present conclusions and recommendations 2.0 WATERSHED DELINEATION 2.1 OBJECTIVES Watersheds are hydrologically connected geographic areas that contain interconnected environmental processes. Watersheds are very effective natural units that are used to analysis the essential physical, chemical and biological ecosystem characteristics and the effects of human influenced on these factors in an area (Ponce 2010). For this reason, the integrated watershed management approach will be used to monitor and assess the integrity and function of the Rio Candelaria. Watershed Management Plan provides a framework for protecting, maintaining and restoring a healthy, natural watershed system where economic and social needs are in balance with the ecological needs of the watershed. The first step in the Integrated Management Plan is to delineate the watershed. A breakdown the watershed delineation process is as follows: • Define the hydrological network within the Candelaria River watershed basin in Champeche, Mexico using topographic maps of Cuilco and Coban, Guatemala, at 1:250,000 created by Instituto Nacional de Estadística y Geografía (INEGI) • Delineate the boundaries of the Candelaria River watershed basin using topographic maps • Delineate the boundaries of the sub watersheds using the same procedure as with watershed boundaries. • Obtain and organize systematically a map database of physical characteristic maps retrieved from digital map data from the Instituto Nacional de Estadística y Geografía INEGI (2003), consisting of the spatial distribution of geology, soils, soil moisture, natural resources, climate and current land use activities within the watershed. 2.2 HYDROLOGICAL NETWORK In order to delineate the hydrological network, the key river (Rio Candelaria), the main tributaries, lakes and wetlands were identified. Delineation of the hydrological network was achieved by using copies of the topographic maps that were obtained from Instituto Nacional De Estadistica y Geografia (INEGI) at a scale of 1:250,000. Transparent papers were used, overlaying the copied topographic maps (which were connected together to cover the bigger region). The identified hydrological network elements (Rio Candelaria, the main tributaries, lakes and wetlands) were traced manually. For a digital form of the hydrological network, a digital picture was taken of the final transparent papers/s of the hydrological network that was traced. It was then Page │ 10
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico integrated into the ArcMap GIS digital map. The manual sketch was georeferenced using UTM coordinates that were obtained from the INEGI maps at 1:250,000 scale. (Refer to Figure 2.1) 2.3 WATERSHED BOUNDARIES 2.3.1 Main Watershed Boundary To delineate the boundaries of the watershed, the topographic maps that were obtained from the INEGI at 1:250,000 scale, were used to identify the topographic controls (contour lines of elevation) and the hydrological network. Since water flows downhill from higher elevations to a common body of water, to delineate the watershed boundary for a particular place on a stream or lake, a line needs to be drawn along the ridge tops connecting the highest elevation points surrounding the lake or stream. In order to identify the Candelaria Watershed boundaries, the outlet (where the water exits the watershed) was identified. Next, the river (Rio Candelaria), the main tributaries, lakes and wetlands were identified. Adjacent water bodies that do not contribute to the flow were also pointed out. The next step was to identify high elevation points that surround the streams and water courses that contribute to the flow. Many of those high elevation points became on the watershed boundary. A preliminary boundary was sketched manually on a copy of one of the maps of the region (Refer to Figure 2.1). A digital picture was taken of the initial sketch for it to be digitized and later integrated into the ArcMap GIS digital map. The digital picture was georeferenced using UTM coordinates that were obtained from the INEGI maps at 1:250,000 scale. The final digitized map was created on an ArcMap GIS database. 2.3.2 Sub-watershed Boundaries Every watershed can be divided into smaller watersheds; sub-watersheds. Identification and delineation of the boundaries of sub-watersheds within the Candelaria watershed was attained by following the network structure and topographic controls that was evident from the topographic map. Three sub-watersheds were identified by separating the watershed’s dendritic hydrological branches coming off the longest flow path. Essentially each sub-watershed contained a dendritic branch of the main stream and was bounded by highpoints surrounding the source water streams, as well as the opposite end of the dendritic branches, the point at which is attached to the longest flow path (Refer to Figure 2.1). Page │ 11
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico Candelaria Watershed Watershed Boundary Delineation, Sub-watersheds & Digital Elevation Map 5 Legend Boundary River Network Lakes Wetlands Sub-watersheds 0 10,000 20,000 30,000 Meters Figure 2.1: Map of the watershed boundary and sub-watershed boundary delineation with the hydrological systems overlaid on the digital elevation model for the Candelaria watershed. 2.4 STREAM MORPHOMETRY Determination of the stream order was performed according to the network morphology. The use of Horton’s hierarchical stream ordering system was used to perform the stream ordering in the Candelaria watershed. This method of stream ordering assigns numbers to stream segments according to the hierarchical position of the stream (Ponce-Hernandez, 2010). Stream ordering began with identifying the first order streams located in the headwaters. The second order streams begin when two first order stream meet. The Candelaria watershed contains three stream orders: 1st, 2nd, and 3rd. Figure 2.2 illustrates the stream morphometry within the sub-watersheds. Following the stream order characterization, the bifurcation ratio was calculated to determine the type of drainage pattern. The bifurcation ratio is the ratio of number of stream segments of one order to the number of the next higher order. For example, the bifurcation ratio for the first order versus the second is determined by dividing the number of first order streams by the number of second order streams. The bifurcation ratios for 1:2 Page │ 12
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico and 2:3 where both calculated to be around 3 indicating that the drainage pattern is dendritic or disturbed (Refer to Table 2.1). The Candelaria watershed was determined to have a disturbed drainage pattern due to the karstic setting, which creates many sink holes scattered over the basin area (Refer to Figure 2.2). Table 2.1: Bifurcation ratio according to stream order and next highest order for the sub-watershed 1st order : 2nd order Bifurcation Ratio 2nd order : 3rd order 3.67 3 Candelaria Watershed Stream Orders & Sub-watersheds Sub-watershed 2 Sub-watershed 1 5 Legend Stream Order 1 Sub-watershed 3 Stream Order 2 Stream Order 3 Sub-watersheds 0 10,000 20,000 30,000 Meters Figure 2.2: Illustration of the stream order characterization within each sub-watershed 2.5 HYDROLOGICAL PARAMETERS Following the generation of the hydrological network, watershed boundary delineation, stream ordering, and hydrological parameters that characterize the watershed’s flow behaviour were calculated. The parameters calculated include: stream number, stream length, drainage area and drainage density. The number of streams divided by stream order was recorded and the sum was calculated to determine the total number of streams located in the watershed. Each stream length was calculated individually and characterized by order. Page │ 13
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico The sum of all the stream lengths was calculated to be 566875 kilometres. This information is summarized in Table 2.2. The drainage area of the three sub-watersheds is 2353.28 km2, 1338.12 km2, and 1560.83 km2 respectively. The total drainage area of the Candelaria watershed is 5252.23 km2. The total length of the stream network and the total watershed area is used to calculate drainage density. Lastly, the drainage density was calculated to measure of how well or how poorly the watershed is drained by stream channels. Drainage density is determined by dividing the total stream lengths by the total area of the drainage basin. This measurement provides useful numerical measure of the texture of the network, and indicates the balance between the erosive power of overland flow and the resistance of surface soils and rocks (Serrano, 2004). The watershed drainage area and drainage density calculations are summarized in Table 2.3. Table 2.2: Summary table of stream order number, length, cumulative length 1st Order Stream Number 33 Stream Length (km) 250625 Cumulative Stream 250625 Length (km) 2nd Order 9 198750 3rd Order 3 117500 449375 Total 45 566875 566875 Table 2.3: Summary table of drainage area per sub-watershed and drainage density Sub-watershed 1 Watershed Drainage Area (km2) Drainage Density (km stream/ km2 land) Sub-watershed 2 Sub-watershed 3 Total 2353.28 1338.12 1560.83 5252.23 = Total Stream Length / Total watershed area = 566875 km / 5252.23 km2 107.9303 Horton’s Laws of drainage composition help to analyze morphometric variety of stream attributes. Horton’s law of stream lengths suggests that a geometric relationship exist between the numbers of stream segments in successive stream orders (Pidwirny, 2006). The relationship between the number of stream segments and stream orders in the Candelaria watershed was found to have negative exponential relationship (Refer to Figure 2.3). Figure 2.4 represents Horton’s law of basin areas which indicates that the mean basin area of successive ordered streams will form a linear relationship when graphed. These relationships represent that stream order, stream length and watershed area govern the structure of the various stream attributes including the structure of the natural branching network (Pidwirny, 2006). Page │ 14
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico Number  of  segments 35 R2  =  0.9977 30 25 20 15 10 5 0 0 1 2 3 Stream  order 4 Figure 2.3: Relationship between number of stream segments and successive stream orders (Horton’s law of stream lengths) 45000 R2  =  0.9496 Stream  L engths  (km) 40000 35000 30000 25000 20000 15000 10000 5000 0 0 1 2 3 4 Stream  Order Stream  order Figure 2.4: Relationship between average stream length and successive stream orders (Horton’s law of basin areas) 2.6 PHYSICAL CHARACTERIZATION OF WATERSHED The Rio Candelaria is considered atypical for this region. Yucatan peninsula is a highly karstic region with high infiltration and features such as swallets and cenotes. These features prevent the development of large surface drainage systems which is why the Yucatan lacks significant rivers. The hydrology of this area is controlled primarily by the interior-draining cenotes aligned along faults. The few small rivers in the Yucatan most often are not connected to a surface drainage network because they tend to have large losses to the numerous subsurface passages which transport water underground (Benke & Cushing, 2005). Recent and quaternary limestone dominated the Candelaria watershed region with a few scattered caliche outcrops. The Page │ 15
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico digital map data for geology of the Candelaria watershed area was at attained from digital from the Instituto Nacional de Estadística y Geografía INEGI (2003). The map data was formatted to create an illustration of the geomorthological features for the Candelaria watershed shown below in Figure 2.5. There are three main rivers, the Caribe, Esperanza, and upper Candelaria that make up the Candelaria river network. The irregular network of these rivers comprise of many wetlands and small streams flowing towards the northwest into the Terminos Lagoon, a large brackish lagoon in western Campeche. There are no dams or reservoirs in the Rio Candelaria stream network, however some prehistoric canal systems still exist which cause very little fragmentation of the river network. The area is dominated by two biomes; tropical savanna to the north and tropical rainforest to the south. The main land use in the area is slash-and-burn agriculture in uplands and cattle ranching in the coastal plains. The upper portions of the watershed basin are limited to small-scale traditional farming, with maize being the most important crop. The lower regions of the basin are mainly used for logging and ranching. There is very little industrial or commercial development in this area (Benke & Cushing, 2005). Current land cover digital map data for the Candelaria watershed area was at attained from digital map data from from the Instituto Nacional de Estadística y Geografía INEGI (2003). The map data was formatted to create an illustration of the current land cover characteristics for the Candelaria watershed shown below in Figure 2.6. Different combinations of the three main soil types; rendzina, gleysols and vertisols dominate the Candelaria watershed area. Rendzina is thin clayey soils rich in organics (humus) and calcium carbonate, reflecting the limestone parent material. There are a few caliche horizons indicating the intensive chemical weathering that occurs during the rainy season followed by rapid evaporation in the dry season (Benke & Cushing, 2005). The vertisols and gleysols are also very clayey soils, however they are much deeper than rendzina, with depths ranging greater than 1.5 meters. The digital map data for soil types of the Candelaria watershed area was at attained from digital map data from from the Instituto Nacional de Estadística y Geografía INEGI (2003). The map data was formatted to create an illustration of the geomorthological features for the Candelaria watershed shown below in Figure 2.5. A visual representation of the soil types in the Candelaria watershed is shown below in Figure 2.7. Page │ 16
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico Candelaria Watershed Candelaria Watershed Geology Current Land Use 5 5 Legend Legend Cultivated Grassland Caliche Forested Area Recent Limestone Seasonal Agricuture Quaternary Limestone Urban Areas Guatemala 0 10,000 20,000 Guatemala 30,000 Meters Figure 2.5: Geology map of the Candelaria Watershed 0 10,000 20,000 Figure 2.6: Current land use map of the Candelaria Watershed Candelaria Watershed Soil Types 5 Legend Gleysol Gleysol, Gleysol, Gleysol, Vertisol, Rendzina, Vertisol, Litosol Solonchak, Gleysol, Rendzina Vertisol, Rendzina, Vertisol, Rendzina, Litosol Guatemala 30,000 Meters 0 10,000 20,000 30,000 Meters Figure 2.7: Soil map of the Candelaria Watershed Page │ 17
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico 3.0 CLIMATIC INVENTORY 3.1 Objective The three main goals for the climatic inventory for the Candelaria River watershed are: 1) to characterize the watershed’s climate characteristics 2) to determine length-of-growing-period (LGP) for the area 3) to estimate maximum surface runoff in the area 3.2 Data Collection from Meteorological Stations in Area Meteorological data was gathered from 16 weather stations in the state of Campeche, Mexico (four of which are located inside the boundary of the watershed) from the National Weather Service Unit, based out of Mexico City, Mexico (SMN, 1961-1990) (see Appendix for individual station data). The following information was collected from each weather station’s inventory that provides data from 1961-1990: ü average maximum monthly temperature ü average minimum monthly temperature ü average monthly temperature ü total monthly evaporation ü total monthly precipitation ü station’s I.D. number, geographical location and descriptive location The climatic data was averaged for all stations within the state of Campeche (Table 1) and within the Candelaria River watershed (Table 2). Due to the variability in the 16 weather stations, analysis of climate data was also made for those within the watershed boundaries.       Table  X  Climatic  data  for  all  16  stations  inside  the  state  of  Campeche,  Mexico  (SMN,  1961-­‐1990).  P=precipitation,   Ev=evaporation,  T=temperature,  ETo=evapotranspiration  estimate,  LGP=length  of  growing  period.   Month   P   (mm/day)   Ev   (mm/month)   Max   Min  T     Avg  T   T  (°C)   (°C)   (°C)   ETo   (mm/day)   ½  ETo   (mm/day)   LGP   Jan   1.63   3.04   28.73   16.99   22.87   3.19   1.60   X   Feb   1.05   3.77   30.03   17.22   23.61   4.02   2.01     March   0.77   4.56   32.81   18.93   25.87   4.73   2.36     April   0.83   5.94   35.14   20.83   28.01   5.43   2.71     Page │ 18
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico May   2.58   5.70   36.00   22.07   29.09   5.24   2.62     June   6.19   4.79   34.43   22.32   28.38   4.93   2.47   X   July   Aug     Sept     Oct     Nov     Dec     6.55   4.00   33.61   21.68   27.66   4.48   2.24   X   6.94   4.37   33.57   21.71   27.65   4.46   2.23   X   7.86   4.07   32.86   21.90   27.40   4.09   2.05   X   5.12   3.58   31.57   20.89   26.24   3.74   1.87   X   2.61   2.80   30.21   18.99   24.62   3.73   1.86   X   1.60   2.52   29.04   17.59   23.34   2.87   1.44   X   Table  X  Climatic  data  for  the  4  stations  located  inside  the  Candelaria  River  watershed  (SMN,  1961-­‐1990).  P=precipitation,   Ev=evaporation,  T=temperature,  ETo=evapotranspiration  estimate,  LGP=length  of  growing  period.   Month   P  (mm/day)   Ev   (mm/month)   Max  T   (°C)   Min  T     (°C)   Avg  T   (°C)   ETo   (mm/day)   ½  ETo   (mm/day)   LGP   Jan   1.81 2.70 28.65 16.88 22.78 3.21 1.60 X Feb   1.37 3.45 30.13 17.18 23.65 4.06 2.03 March   0.86 4.88 33.00 18.45 25.75 4.77 2.38 April   0.90 5.78 35.55 20.13 27.85 5.47 2.74 May   3.22 6.03 36.65 21.73 29.18 5.27 2.63 X June   7.17 4.85 34.40 21.90 28.18 4.90 2.45 X July   Aug     Sept     Oct     Nov     Dec     6.61 4.48 33.53 21.18 27.33 4.44 2.22 X 6.75 4.45 33.63 21.35 27.48 4.44 2.22 X 7.77 4.20 32.83 21.68 27.28 4.11 2.05 X 5.23 3.65 31.55 20.73 26.15 3.77 1.88 X 3.01 3.03 30.35 19.15 24.75 3.83 1.91 X 1.64 2.60 29.23 17.68 23.45 2.79 1.39 X Page │ 19
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico CAMPECHE Candelaria Watershed Meteorological Stations CHAMPOTON 5 PUSTUNICH lf Gu co exi of M SABANCUY PIXOYAL ISLA DE AGUADA CIUDAD DEL CARMEN 2 CIUDAD DEL CARMEN 1 ESCARCEGA 1ESCARCEGA 2 SAN ISIDRO CANDELARIA 1CANDELARIA 2 Legend Meteorological Stations LA ESPERANZA MONCLOVA MIGUEL HIDALGO Candelaria Watershed GUATEMALA 0 15,000 30,000 45,000 Meters Fig.  1  Locations  of  16  meteorological  stations  in  the  state  of  Campeche,  used  in  the     climatic  inventory  of  the  Candelaria  River  watershed.       3.3 Evapotranspiration (ETo) Estimation There two main descriptive definitions for evapotranspiration: potential and actual (Zhang et al. 2007). Potential evapotranspiration is the maximum amount of water that can be evaporated from plants and the soil in an area, while actual precipitation is the average amount of water that is evaporated from plants and soil, either measured directly or through estimation (Zhang et al. 2007). Estimates were made for the stations found here using CropWat Version 4.3 (FAO software). Air humidity %, wind speed (km/day) at 2m from sea level, and daily sunshine hours were retrieved from two weather stations: Campeche, Campeche and Flores, Guatemala given by ClimWat Version 2.0 (FAO software). These variables were averaged and used in the estimates for evapotranspiration (ETo) for all 16 meteorological stations used, along with maximum and minimum temperature per month and total precipitation per month using the automated Penman-Monteith equation: Page │ 20
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico     Evapotranspiration values were then used to estimate length-of-growing period for each station. 3.4 Length-of-growing-period (LGP) Estimation LGP describes the time period for which climatic conditions provide adequate plant growth in an area over an annual period. The growing period is determined for a given weather station based on the following: LGP begins when precipitation is more than 50% of the amount of evapotranspiration and ends approximately 5 days after the rainy period ends, when precipitation is less than 50% the amount of evapotranspiration (PonceHernandez, 2010). The growing period occurs only at temperatures above 6.5 °C (Ponce-Hernandez, 2010). The LGP value indicates the potential for adequate plant growth, where a high LGP value suggests that an area is equipped for satisfactory plant growth to occur. The average LGP determined for all 16 stations is 250 days (Table 1), while the average LGP determined for the four stations located in the Candelaria River watershed is 281 days (Table 2). The inconsistency between LGP estimates is important to note that for stations inside the watershed, precipitation is much higher than for northern stations (Fig. 1). The gradient of LGP within the watershed ranges from 235 days to 293 days (Fig. 2). Geostatistical analysis was done using semivariogram Kriging method on the ArcGIS software to create a predictive model for LGP values in the watershed, using the 16 meteorological stations as data points. Page │ 21
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico Candelaria Watershed Length of Growing Period (LGP) 5 Legend 235 - 253 days 254 - 266 days 267 - 280 days 281 - 293 days Guatemala 0 10,000 20,000 30,000 Meters   Fig.  2  Predictive  interpolation  model  of  LGP  for  areas  within  the  Candelaria  watershed  boundary.     3.5 Climograph Data Climographs provide comprehensive visual demonstrations of LGP and the water balance between precipitation and evapotranspiration (Ponce-Hernandez, 2010). Average daily precipitation per month is plotted alongside daily evapotranspiration per month and 50% of daily evapotranspiration per month, and the five climatic conditions depend on the relationship between these three variables. Climographs were produced for all 16 weather stations (see Appendix A) and a climograph was produced using averaged climatic data across all stations (Fig. 2).   Page │ 22
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico   Fig.  2  Climograph  for  all  16  meteorological  stations  in  the  area.  P=precipitation,  ET=evapotranspiration,  ½  ET=  50%  evapotranspiration,   ER=end  of  rainy  season,  E=end  of  LGP,  B=beginning  of  LGP,  BH=beginning  of  humid  period,  EH=end  of  humid  period.       3.6 Soil Moisture and Climate Type of Candelaria Watershed To corroborate with the collected climate data from the weather stations, a map database was retrieved from digital map data from the Instituto Nacional de Estadística y Geografía INEGI (2003). Months of soil moisture available inside the watershed area is illustrated in the form of a digital map (Fig. 3). The months of soil moisture in the watershed are 8 months and 9 months, correlating well with the LGP interpolated model presented (Fig. 2). The majority of precipitation falls between June and October due to the beginning of the summer trade winds and tropical cyclones, which is the rationale for this trend. Page │ 23
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico Candelaria Watershed Soil Moisture 5 Legend 8 months 9 months Guatemala 0 10,000 20,000 30,000 Meters Fig.  3  Months  of  soil  moisture  inside  the  Candelaria  watershed  (MaDGIC,  2010).         The climate type was illustrated as a digital map, also retrieved from INEGI (2003). The Candelaria watershed is described as a warm subhumid climate, just north of the warm humid climate that is further inland from the ocean’s influence (Fig. 4). This area is described as a tropical monsoon that is characterized by distinctive cyclic wet and dry seasons.     Page │ 24
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico Candelaria Watershed Climatic Regions 5 Legend Warm Humid Warm Subhumid Waterbody Guatemala 0 15,000 30,000 45,000 Meters   Fig.  4  Climatic  regions  for  climate  type  in  Candelaria  watershed  (MaDGIC,  2010).   4.0 ECOLOGICAL ZONES 4.1 PROCEDURE Ecological zones (Ecozones) are defined as unique areas of land that are determined by climate, soils and landscape units (Ponce-Hernadez 2010). The Ecozones for the Candelaria watershed were determined using the integrated approach. This approach used the overlaying of digital maps with boundaries of thematic information to identify broad patterns of similar rock or geological material, soil, land cover and topography (Ponce-Hernadez 2010). These broad patterns tentatively identify Land Systems in the area (Ponce-Hernadez 2010). This information can then be used as a management technique with the Hydrological Response Units (HRU). 4.2 LAND FACETS The watershed was first divided into land systems by locating generally linked land facets usually distinct and bounded in a locality as a local form (Ponce-Hernadez 2010). When determining land facets, the mosaic of land cover types as viewed from aerial photographs and satellite imagery taken from NASA and Google Earth (Figure 4.1). These images were then overlaid and traced into the ArcMap database. After Page │ 25
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico extensive analysis of the images, a total of 228 land facets were traced and mapped onto the Candelaria watershed map. 4.3 ZONING Zoning is the partitioning of spatial multi-attribute variability into areas or zones that are relatively homogeneous in all attributes or with acceptable variations that are simple and consistent. The attributes or variables used for defining zones are relevant permanent of semi-permanent bio-physical and morphological variables of the environment (Ponce-Hernadez 2010). When zoning for the Candelaria watershed, a soil map was overlaid onto a geology map which was then overlaid by a climate map and finally by the land facets map. The end result of this was the Ecozones map, where selected characteristics for each Ecozone were placed into an attribute table (Refer to Figure 4.1). This map represents approximation to the Ecozones in the watershed and the tentative hydrological response units. Appendix X illustrates the different land systems within the Candelaria watershed. These figures demonstrate the patterns of the land systems and their attributes. Candelaria Watershed Ecological Zones & Land Systems Northeast Land System Northwest Land System North Land System 5 Central Land System Southeast Land System Legend EcoZones Guatemala 0 10,000 20,000 30,000 Meters Figure 4.1: Map of the ecological zones located in each of the land systems of the Candelaria Watershed Page │ 26
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico 5.0 SURFACE RUNOFF ESTIMATION 5.1 OBJECTIVE Determining the mass water balance in a watershed is critical for anticipating volumes of flow through the stream network system. With the knowledge of the water balance for the watershed, phenomena such as floods and droughts can be prepared for. It is essential to determine estimates of the maximum, minimum, and mean runoff over the area of the watershed for planning for such phenomena (Ponce-Hernadez 2010). 5.2 INTENSITY- DURATION-FREQUENCY CURVES (IDF) Data on rainfall intensity within the Candelaria watershed was obtained by using intensity-duration- and-frequency (IDF) curves for Mexico, provided from the National Weather Service Unit, based out of Mexico City, Mexico. The IDF curves were used to determine the return period for 2, 3, 5, 10, 25, 50 and 100 years. Figure 5.1 Figure 5.2 and Figure 5.3 illustrated the three IDF Curves. Figure 5.1 was used to determine the intensity for sub-watershed 1, Figure 5.2 was used to determine the intensity for sub-watershed 2 and Figure 5.3 was used to determine intensity for sub-watershed 3. 5.3 CONCENTRATION TIME (TC) Time of concentration is a fundamental watershed parameter used to determine the peak discharge for the watershed. Time of concentration can be defined as the time delay for a drop of water to run through the discharge between maximum headwaters and discharge point (Ponce-Hernadez 2010). The time of concentration is calculated using: Tc= 0.02 x (L1.15/ H0.385) Where: L=  Maximum  length  of  the  watershed   H=  Elevation  or  height  difference  between  headwaters  and  discharge  point     The concentration time for the Candelaria watershed was calculated using climate data provided form the National Weather Service Unit, based out of Mexico City, Mexico (SMN, 1961-1990). When determining the storm duration, it was assumed to be half the concentration time. To determine this the maximum length of the watershed was calculated along with the data obtained from 16 climate stations located inside the watershed (Refer to Figure 5.4 located in the Climatic Inventory section) was used. (See Table 5.1 for the breakdown of the calculations for concentration time) Page │ 27
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico 5.4 RAINFALL INTENSITY (I) The rainfall intensity for the return period for 5 and 50 years was obtained for each sub-watershed. This data was acquire by using values from the concentration time (section 5.2) these values were used as entry points to the IDF curve. 5.5 RUNOFF COEFFICIENT (C) The runoff coefficient is determined using soil texture, land cover and mean slope (Ponce-Hernadez 2010). To determine the runoff coefficient for the Rio Candelaria watershed, a land use table was created, and a soil texture map and slope map were extracted and documented for each subwatershed (Table 5.3). 5.6 AREA OF SUB-WATERSHEDS (A) When determining the area for the Candelaria watershed each sub-watersheds area was calculated using the Arc-measure tool in ArcGIS from the extracted Rio Candelaria watershed digital map. 5.7 CALCULATION OF MAXIMUM RUNOFF (Q) The maximum runoff for each sub-watershed was calculated using the equation: Qmax (m3/sec) = 0.028CiA Where: C=Runoff Coefficient I= Rainfall intensity for 5 and 50 years return period (cm/hr) A=Area of each sub-watershed (ha) 5.8 AVERAGE PRECIPITATION (PM) Precipitation data for the Candelaria watershed was obtained from the climate station data provided by the National Weather Service Unit, based out of Mexico City, Mexico (SMN, 1961-1990). 5.9 CALCULATION OF AVERAGE RUNOFF (VM) The average runoff (Vm) for the sub-watersheds were calculated using the equation: Vm(m3)= A.C.Pm Where: A= Area of each subwatershed (km2) C= Runoff Coefficient Pm= Average Precipitation (mm) Page │ 28
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico 5.10 RESULTS The runoff data indicates that maximum intensity for each return period increases as the return periods increase (Table 5.1). Therefore, it can be predicted that the predicted 50 year storm will be much more intense then the predicted 5 year storm. Table 5.2 shows the breakdown for the calculations for the concentration time using the equation in section 5.2. The concentration time for the sub-watershed 1, 2 and 3 were 34.71 min, 16.73min and 25.98min respectively. As indicated, sub-watershed 1 has the highest concentration time because it is closest to the delta of the basin and is where the stream networks meet up. Table 5.3 shows the percentage land cover, soil texture and total area of each sub-watershed. Table 5.4 shows the rainfall intensity in cm/hr for each sub-watershed and the maximum runoff for each sub-watershed calculated. Sub-watershed 2 has the highest maximum runoff compared to the other sub-watersheds with a maximum runoff of 1.9 for 5 year return period and 2.82 for 50 year return period. Sub-watershed 1 has lowest maximum runoff of 0.91 for 5 years return period and 1.42 for the 50 year return period. Therefore it can be predicted that both the intensity and runoff for the 50 year storm will be greater then the 5 year storm. Figure 5.1: IDF curve used to determine intensity for sub-watershed 1 (coastal) Page │ 29
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico Figure 5.2: IDF curve used to determine intensity for sub-watershed 2 (upper) Figure 5.3: IDF curve used to determine intensity for sub-watershed 3 (mid) Table 5.1: Maximum Rainfall Intensity for each Return Period Page │ 30
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico Sub-watershed 1 Sub-watershed 2 Sub-watershed 3 Rainfall intensity in m/sec Rainfall intensity in m/sec Rainfall intensity in m/sec -6 -6 1.90 x10 4.23 x10 2.18 x10-6 2.18 x10-6 4.86 x10-6 2.68 x10-6 2.54 x10-6 5.36 x10-6 2.89 x10-6 -6 -6 3.03 x10 6.27 x10 3.45 x10-6 3.45 x10-6 7.40 x10-6 3.88 x10-6 -6 -6 3.95 x10 7.83 x10 2.22 x10-6 4.58 x10-6 9.03 x10-6 4.86 x10-6 Return Period (Years) 2 3 5 10 25 50 100 Table 5.2: The breakdown of the calculation for concentration time Sub-watershed 1 2 3 Maximum length (m2) 2348500000 1219840000 2092890000 Elevation difference (head & discharge) (m) 175 137 112 TC (min) ½ TC 34.70674366 17.35337183 16.73247715 8.366238573 25.98089721 12.99044861 Table 5.3: Soil texture, Land cover and Area of each sub-watershed Sub-watershed Soil Land Cover 1 Clay Loan & Silty Loam Clay Loan & Silty Loam Clay Loan & Silty Loam >30% Grassland Sub-watershed Area (km2) (A) 2348.05 0.05% Forest 1219.84 >30% Grassland 2092.89 2 3 Table 5.4: The breakdown calculations for Maximum Runoff of return period for 5 and 50 years for each subwatershed Maximum Runoff (i) Rainfall Intensity (cm/hr) Sub-watershed Tc 5 50 1 2 3 1.42 2.82 1.55 34.71 16.73 25.98 0.91 1.9 1.0 (C) Runoff Coefficient 0.42 0.5 0.42 (A) Sub-watershed Area (Ha) 234805 121984 209289 Q (m3/sec) for 5 years 25249.39 32966.61 25631.34 Q (m3/sec) for 50 years 20404.78 82609.72 38134.43 Page │ 31
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico 6.0 LAND USE INVENTORY 6.1 OBJECTIVES • To introduce a systematic approach to deal with land use systems by providing a hierarchy of units in a classification system, in terms of: Division, Sub-division and class of land use present in the designated watershed • To identify the Production Systems (PS) and their component sub-systems along a garden of capitalization • • 6.2 To provide land use inventory of LUTs and PS occurring within the watershed To identify, classify and characterize the details of LUTs occurring within the watershed PROCESS The LUTs for the Candelaria watershed were rice, vegetables, livestock, backyard poultry, livestock, fisheries, backyard agro-forestry, plantation agro-forestry, beans, corn, sugar cane and sorghum. The primary criteria used to determine the land utilization types (LUTs) for the Candelaria watershed consisted of the products market orientation, capital intensity, labour intensity, power source, level of mechanization, size of the farm enterprise, land tenure, infrastructure requirements, inputs and current management practices. The categories were then further separated, for market orientation sub-criterion was separated according to commercial, mixed or subsistence orientation. Capital intensity was broken into high, medium and low. Labour intensity was categorized as high, medium or low. Power source was separated into either petrol engine or hand labour. Mechanization (use of machinery) was subcategorized into high, medium, low or none. Farm enterprises were categorized under two heading: large (no less then 50ha) and regular (less then 50ha). Land tenure can be owned privately or be the government. Infrastructural requirements criteria were subject to change based upon the utilization of the land, for this particular study the products were categorized into refrigeration, roads and storage units. Inputs were also subject to change depending on requirements of the land utilization the products were sub-categorized into the used of pesticides, herbicides, fertilizers and equipment. When determining management practices the information was very limited. Therefore tillage cultivation and not applicable were the only sub-categorizes used. All criterions were summarized into a table and subjective criterion for the few categories mentioned above were incorporated into the table using web internet sources. A complete table of the LUT and the criteria they were based on can be found in Appendix… 6.3 RESULTS Page │ 32
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico The summary table in appendix … reflects that the land utilization types were typically mixed between commercial and subsistence. The activities were generally performed with high to medium intensity using both hand labour and petrol engines for power. Mechanization found to be mainly high to medium usage for large scale farms and medium/low for smaller farms. Within the Candelaria watershed, the land is mainly privately owned as this area mainly contains smaller communities as opposed to large cities. 7.0 LAND CAPABILITY ASSESSMENT 7.1 PURPOSE AND PROCEDURES Land capability is the maximum intensity of land use that a particular relatively homogenous area of land can support without depleting the resource (Ponce-Hernandez, 2010). Land capability is assessed by applying it to units of land with known land uses, topography, and soil characteristics in order to determine its capability to support specific types and levels of agricultural land use. Land Capability Assessment is categorized in eight capability classes (Figure 7.1). Those classes ranged from 1 to 8, where Class 1 land can potentially be good for wildlife, forestry, grazing and cultivation. Whereas Class 8 is only good for wildlife, and the other classes vary in uses between those two classes. Figure 7.1: The intensity with which each Land Capability class can be used with safety and the limitations of the possible land use per class (Ponce-Hernandez, 2010). A Land Capability Assessment was prepared according to the EcoZone (EZ) attribute tables. The criterion used for limiting factors, in degree of importance, was topography (Slope %), wetness (flooding and drainage), physical soil conditions (surface texture, coarse fragments, stoniness, rockiness and soil depth) and Page │ 33
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico soil fertility (C.E.C., base saturation and organic matter). The Land Capability was obtained by the use of Land Capability Classification criterion provided by Ponce-Hernandez (2010) (Figure 7.2). Figure 7.2: Land Capability Classification showing the criteria and threshold values (Ponce-Hernandez, 2010).   The most limiting factor (topography, wetness, physical soil conditions and soil fertility) was indicated by a letter (t, w, s and f, respectively) following the Land Capability Assessment class. For the Candelaria Watershed, the limiting factors found for the 305 EcoZones was either wetness (flooding and drainage) or physical soil conditions (mostly soil depth) (Appendix Land Capability). 7.2 RESULTS Based on the Land Capability Assessment performed, the Candelaria Watershed showed six potential fields that are most suitable for each of its EcoZones (Figure 7.3). The assessment shows that the watershed is capable for intense cultivation of rice in most of its south, south-east, central and north-western EcoZones. This is because rice can sustain flooding and excessive draining. The watershed has a very low capability of moderate cultivation. It can only be found in three small Ecozones in the central-northern region. Limited cultivation mostly dominates the central-north and some parts in the west. There are many smaller EcoZones that has limited cultivation fragmented throughout the eastern parts of the watershed. This limited cultivation is Page │ 34
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico caused by the soil texture in those areas (Figure. 2.7). They consist of Vertisol, Rendzina and Litosol which have small soil depths that limit the cultivation. The watershed’s capability for forestry can only be found in two EcoZones in the north-west. A capability for moderate grazing can be found in eight EcoZones in the north-west and central areas. Lastly, the Candelaria Watershed has a capability to support wildlife only in most of its north-east, north-west (by the discharge point into the Gulf of Mexico) and at different EcoZones throughout the watershed (floodplains and wetlands mostly) (Figure 7.3). These EcoZones are only suitable for wildlife because they do not have much slope (mostly flat), they have karstic environments, and are on floodplains and wetlands. Refer to Appendix (Land Capability) for the exact land use that each EcoZone is capable to accommodate. Candelaria Watershed Land Capability 5 Legend Cultivation (Limited) Cultivation (Moderate) Cultivation (Rice only) Forestry Grazing (Moderate) Wildlife Guatemala 0 10,000 20,000 30,000 Meters Figure 7.3: A map of the Candelaria Watershed Land Capability Assessment Results. 7.3 CANDELARIA WATERSHED “HOT SPOTS” Hotspots are defined as areas in which its current land use intensity is most likely depleting a resource and potentially degrading the environment. Following the classification of each EcoZone according to their land Page │ 35
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico capabilities, the areas that were found exceeding the maximum intensity of land use determined for that land use, hotspots, were identified. The Land Capability Assessment of the Candelaria Watershed exposed 124 current EcoZone hot spots. These are considered hotspots because of the flood risk and excessive drainage (most of them are on the floodplains); rice is the only main crop grown in the watershed that can sustain those situations. Thus, if any of the current cultivated land use (Figure 2.6) is rice, then those Ecozones are not “Hotspots”. For any other crops that are currently being grown there, they are considered “Hotspots”. It is clear that there is a concentration of hotspots on flood plains by the rivers and streams throughout the watershed, in central, north-east and southwest EcoZones. Moreover, 145 potential “Hotspots” were found. Potential Hotspots are EcoZones that are crop specific; they can only sustain certain spots (such as rice). Lastly, 39 EcoZones were found to be sustainable at the current land use (Figure 7.4). Candelaria Watershed HOTSPOTS 5 Legend Hotspot Potential Hotspot Sustainable Guatemala 0 10,000 20,000 30,000 Meters Page │ 36
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico Figure 7.4: Map of the calculated Hotspots in the Candelaria Watershed 8.0 LAND SUITABILITY ASSESSMENT 8.1 PURPOSE AND PROCEDURES Land Suitability Assessment is the evaluation of Land Utilization Types (LUTs) that has high intensity (the EcoZones in which their Capability indicated that their agricultural and grassland activities are sustainable). It is a land evaluation of performance of the land for specific alternative uses. The objective of the Land Suitability Assessment is to determine which activity can be done on a given tract of land sustainably and to determine the best land for a given intended use as well. Suitability classes were determined by the matching of land qualities to land use requirements (Ponce-Hernandez, 2010). A diagnosis of Land Use of Hot Spots was performed. A Land Sustainability Assessment was carried out by compiling LUTs for the areas that there were assessed. Then the Length of Growing Period (LGP) of the EZ was evaluated. The next step was the identification and ordering of Land Use requirements, soil/land characteristics to the required LGP/crop. Then an assignment of suitability classes to each interval of each the range explored. Next, the ranges of requirements were organized according to their importance. Lastly, an assessment of suitability of LUTs and a generation of a map per LUT were attained. Eight main crops are grown and used in Campeche, Mexico (where Candelaria, Watershed is). These crops are grown there for human needs, sustainability, and for food security requirements. These crops are: banana, coconut, dry beans, maize, rice, sorghum, squash and sugar cane. Also, for the live stock grazing, African Stargrass is grown. The criteria that was used for assessing those crops was according to their annual precipitation (rainfall), LGP, mean temperature during LGP and soil depth. The following set of tables (Tables 8.1-8.4) explains this, where S1 stands for suitable; S2 for moderately suitable; S3 for marginally suitable; N1 for actually unsuitable but potentially suitable; and N2 for actually and potentially unsuitable (Ponce-Hernandez and Beernart, 1991a). Table 8.1: Annual rainfall (mm) required for the growth of each of the crops (Ponce-Hernandez and Beernart, 1991a). Crop Banana Coconut Dry beans S1 1’500-1’800 1’700-2’000 400-500 S2 1’250-1’800 1’450-1’700 S3 1’000-1’250 1’250-1’450 N1 - N2 < 1’000 < 1’250 Page │ 37
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico Maize Rice Sorghum Squash Sugar cane (10 day) Livestock grazing 750-850 1’250-1’600 1’500-2’000 600-800 1’000-1’200 300-460 60-70 600-750 1’600-1’800 500-600 > 1’800 - < 500 400-600 1’200-1’400 350-400 1’400-1’500 - > 1’000 < 350 > 1’500 50-60 30-50 - < 30 Table 8.2: Length of growing season (LGP) (in days) required for the growth of each of the crops (PonceHernandez and Beernart, 1991a). Crop Banana Coconut Dry beans S1 90-120 S2 - S3 - N1 - Maize 130-150 220-270 110-210 120-150 210-240 110-130 270-325 325-345 90-110 - 90-120 240-270 75-90 270-300 - - - - - Rice Sorghum Squash Sugar cane Livestock grazing N2 < 80 > 145 < 90 > 345 < 110 < 75 > 300 -   Table 8.3: Mean temperature required for the length of growing period (LGP) (Celsius) required for the growth of each of the crops (Ponce-Hernandez and Beernart, 1991a). Crop Banana Coconut Dry beans Maize Rice Sorghum Squash Sugar cane S1 18-22 24-26 32+ 15-20 S2 16-18 22-24 18-22 26-32 22-30 21-24 26-32 18-27 24-26 30-32 16-18 32+ S3 14-16 20-22 14-16 N1 - N2 < 14 < 20 - < 10 > 27 < 14 < 12 < 15 18-21 > 32 15-18 - 20-24 32-34 16-20 34-35 - < 13 < 16 > 35 Livestock grazing Page │ 38
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico     Table 8.4: Soil depth (cm) required for the growth of each of the crops (Ponce-Hernandez and Beernart, 1991a). Crop Banana Coconut Dry beans Maize Rice Sorghum Squash Sugar cane Livestock grazing S1 75-100 > 75 > 75 75-100 > 90 50-90 > 120 80-125 S2 50-75 50-75 50-75 50-75 S3 25-50 25-50 25-50 20-50 N1 - N2 < 25 < 25 < 25 < 20 20-50 10-20 - < 10 50-80 25-50 - < 25   8.2 CLIMATIC AND SOIL REQUIREMENTS OF THE CROPS Climate requirements for growing crops include annual precipitation levels, soil moisture, soil temperature and air temperature. Moreover, there are each crop require certain soil types, soil textures, soil depths, drainage levels, slope percentages, acidities (pH), alkalinities, salinity levels and nutrient requirements. The Food and Agriculture Organization (FAO) divides basic soil requirements for crops into two main categories of requirements; internal and external. For the internal requirements; soil temperature regime which is directly related to daily temperature fluctuations; soil moisture regime which relates to permeability, soil moisture balance and drainage levels; soil aeration regime which is the capacity of a soil to transport oxygen to the root zone and allow for the release of CO2 (these two are important in determining a crop’s suitability for a given soil); natural soil fertility; soil depth; soil texture; and the presence or absence of toxins in the soil. All those factors can limit or enhance crop growth and yield (Ecocrop, 2010). External requirements for crops are: soil slope; topography; susceptibility to flooding during the growing season; and the depth of flooding when it occurs. All those factors influence the growth and agricultural land use sustainability (Ecocrop, 2010). The following are detailed requirements for each of the crops: 8.2.1 Banana Banana requires a temperature range between 15 and 35 Celsius to grow (Optimum: 25-30 Celsius) and it is frost intolerant. Required annual precipitation is 1200 mm of rain in a humid environment or 2200 mm in Page │ 39
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico dry climates and prefers humidity over 60%. Banana is a day neutral crop and requires a soil depth of over 75 cm and can tolerate a slope that is less than 8%. It accepts alluvial soils, former swamps if drained, and ferrisols and latosols derived from limestone. The soil texture for its growth is sandy loam to silty clay (Clay loam is preferred) with coarse fragments less than 15% of the total soil volume. For drainage, moderate to well drained soils are required (Ponce-Hernandez and Beernart, 1991a; Ponce-Hernandez and Beernart, 1991b). 8.2.1 Coconut The second crop on the list, coconut, requires warm sunny conditions without a great diurnal temperature variation and the ideal temperature is around 29 Celsius. Annual precipitation needed for its growth ranges from 1250 mm to 3800 mm with an optimal amount of 1700 mm, whereas it requires humidity over 60%. Day length is not critical for coconuts. Optimal soil depth for its growth is more than 1 m (over 75 cm acceptable) and can tolerate a slope that is less than 8%. Coconut prefer light soils and does well on alluvial and sandy soils near costs with an acceptable coarse fragments of less than 15% of the soil volume. For drainage, like banana, coconut needs moderate to well drained soils (Ponce-Hernandez and Beernart, 1991a; PonceHernandez and Beernart, 1991b). 8.2.3 Dry beans Beans can grow at many locations but not the humid tropics. Mean daily temperatures range from 10 to 27 Celsius (15-20 Celsius is optimal). They are frost sensitive and their flowers starts getting damaged at 5 Celsius or less. Beans require an annual precipitation of 400 to 500 mm throughout the growing season and require medium to high humidity (especially at flowering). For required light, beans range between day neutral and short day plants. Required soil depth is at least 0.5 m (optimal: over 75 cm). The soil needed for its growth range from loamy sand to kaolinitic clay (the optimum range is from loam to clay loam including silty clay loam and sand clay loam) and a slope that is less than 8% (Ponce-Hernandez and Beernart, 1991a; PonceHernandez and Beernart, 1991b). 8.2.4 Maize The optimum temperature for its germination is between 18 and 21 Celsius. The maize’s growing period must be frost free. An annual precipitation range of 750 to 1600 mm (800 – 1200 mm is optimal) and a moderate humidity are required. Maize is a day neutral or short day plant. Minimum soil depth of 0.45 to 0.65 m is needed (optimal over 75 cm), stoniness is a limiting factor and a slope of less than 8% is optimal (up to 30% is acceptable). Soil types that are acceptable are ferruginous soils, ferrisoils, and well drained alluvial soils, while the textures are silty loam, sandy loam, loam, silty clay loam, clay loam and sandy clay loam. For drainage, well drained conditions are needed (Ponce-Hernandez and Beernart, 1991a; Ponce-Hernandez and Beernart, 1991b). 8.2.5 Rice Page │ 40
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico Rice’s growing period can go up to 210 days (at least 110). Germination does not occur on soils with a temperature less than 12 Celsius. (Optimal: 22 – 35 Celsius) and it is sensitive to frost. Annual precipitation needed ranges between 1500 – 2000 mm (optimal: 1600+ mm) and a minimum of 1000 – 1300 mm. Rice requires abundant sunshine (over 75%) while it grows in a wide range of humidity levels. Soil depth of over 90 cm and slopes of less than 8% are acceptable. Soil types should be alluvial soils and gleys with, preferably, a massive clay and silty clay, block texture (Ponce-Hernandez and Beernart, 1991a; Ponce-Hernandez and Beernart, 1991b). 8.2.6 Sorghum Soil temperatures must exceed 10 degrees Celsius for germination of sorghum. Acceptable temperatures: 15 – 35 Celsius (optimal: 23 – 34 Celsius). Sorghum will not grow in frost conditions. It needs a minimum annual precipitation range of 350 – 1000 mm (600 – 800 mm is optimal) with a medium to high humidity (over 85%). Sorghum is a short day plant (needs abundant sunshine) and requires a dark period of 1114 hours. Soil texture required for its growth ranges from loamy sand to heavy clay (optimal: silt loam to clay) with coarse fragments of less than 15% of the soil volume. Soil depth of over 0.5 m is acceptable (optimal: 1-2 m) (Ponce-Hernandez and Beernart, 1991a; Ponce-Hernandez and Beernart, 1991b). 8.2.7 Squash Squash is a native plant to Mexico and Central America. Its germination temperatures ranged from 15.6 to 37 Celsius (18-27 Celsius is optimal) and it is not frost hardy. It requires annual precipitation of 300 – 460 mm during growing season with low to medium humidity. Lighter soil textures are preferred with a well drained soil that has a depth of over 1.2 m (Ponce-Hernandez and Beernart, 1991a; Ponce-Hernandez and Beernart, 1991b). 8.3.8 Sugar cane Sugar cane has a very long growing period (270-365 days). Preferred temperatures range from 15 to 45 Celsius (22-35 Celsius optimal) and less than 15 Celsius will result in no growth. Annual precipitation should be more than 1300 mm (around 1600 mm is better). Moderate to high humidity and a high level of radiation are needed for its growth. A soil depth of 0.5 – 1 m (over 80 cm is better, and an optimum of 1 – 5 m) and a slope of less than 8% are needed. Soils texture of sandy loam to monmorillonit clay (optimal: silt loam to clay) with coarse fragments of less than 15% of the volume. An optimal drainage level of imperfectly drained to moderately drained is needed (Ponce-Hernandez and Beernart, 1991a; Ponce-Hernandez and Beernart, 1991b). 8.3.7 African stargrass Page │ 41
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico African stargrass is grown in the Candelaria Watershed region for livestock grazing. According to the Ecocrop website, African stargrass can tolerate a wide range of soil fertility levels. It can mobilize and recycle subsoil nutrients, especially calcium (Ecocrop, 2010). 8.3 RESULTS According to the Land Suitability Assessment that was performed, banana and maize are moderately suitable (S2) in EcoZones in the central-northern areas as well as some EcoZones to the west of those areas. Marginally suitable (S3) EcoZones were found throughout the western parts of the Candelaria Watershed for those two crops. Most of the EcoZones in the watershed (all the other EcoZones) are not suitable (N2) for cropping banana or maize (Figures 8.1 and 8.2). Candelaria Watershed Candelaria Watershed Land Suitability MAIZE Land Suitability BANANA 5 Legend 5 Legend Moderately Suitable (S2) Moderately Suitable (S2) Marginally Suitable (S3) Marginally Suitable (S3) Not Suitable (N2) Not Suitable (N2) Guatemala Guatemala 0 10,000 20,000 30,000 Meters Figure 8.1 – Land Suitability Assessment: Banana 0 10,000 20,000 30,000 Meters Figure 8.2 – Land Suitability Assessment: Maize Coconut, dry beans, squash and sugarcane are all either marginally suitable (S3) or not suitable (N2). The same Ecozones that showed suitability (as S2 and S3) for the two crops mentioned are marginally suitable (S3), while the same not suitable EcoZones found for banana and maize are of those for coconut, dry beans, squash and sugarcane (Figures 8.3-8.6). Page │ 42
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico Candelaria Watershed Candelaria Watershed Land Suitability DRY BEANS Land Suitability COCONUT 5 5 Legend Legend Marginally Suitable (S3) Marginally Suitable (S3) Not Suitable (N2) Not Suitable (N2) Guatemala Guatemala 0 10,000 20,000 0 30,000 Meters Figure 8.3 – Land Suitability Assessment: Coconut 10,000 20,000 30,000 Meters Figure 8.4 – Land Suitability Assessment: Dry Beans Candelaria Watershed Candelaria Watershed Land Suitability SUGARCANE Land Suitability SQUASH 5 5 Legend Legend Marginally Suitability (S3) Marginally Suitable (S3) Not Suitable (N2) Not Suitable (N2) Guatemala Guatemala 0 10,000 20,000 30,000 Meters Figure 8.5 – Land Suitability Assessment: Squash 0 10,000 20,000 30,000 Meters Figure 8.6 – Land Suitability Assessment: Sugarcane The Ecozones that were found moderately suitable for banana and maize were suitable (S1) for sorghum, whereas the ones there were found marginally suitable for banana and maize were found to be moderately suitable (S2) for sorghum. The same large number of EcoZones that was found not Page │ 43
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico suitable (N2) for the other crops is of that for sorghum (Figure 8.7). The suitable category for sorghum makes it one of the most sustainable crops to be grown in the Candelaria Watershed. Candelaria Watershed Land Suitability SORGHUM 5 Legend Suitable (S1) Moderately Suitable (S2) Not Suitable (N2) Guatemala 0 10,000 20,000 30,000 Meters Figure 8.7 – Land Suitability Assessment: Sorghum Rice is different from the other crops. Most of the Candelaria Watershed (excluding most of the northeastern, north-central, up most north (the discharge area) and most of the flood plains EcoZones) show that rice is moderately suitable, whereas EcoZones in the central-northern areas as well as some EcoZones to the west of those areas are marginally suitable. Rice shows this ability to be grown in those EcoZones because these EcoZones are at higher risk of flooding and excessive draining. It is observable that those EcoZones can only sustain rice because it’s the only crop that can sustain those conditions. Lastly, the north-east EcoZones, up most north EcoZones of the discharge area and most of the flood plains EcoZones are not suitable for rice growth (Figure 8.8). Page │ 44
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico Candelaria Watershed Land Suitability RICE 5 Legend Moderately Suitable (S2) Marginally Suitable (S3) Not Suitable (N2) Guatemala 0 10,000 20,000 30,000 Meters Figure 8.8 – Land Suitability Assessment: Rice All those that are moderately suitable and marginally suitable for rice are considered suitable for livestock grazing (of African stargrass). But if those areas are exposed to high flooding, they might not be able to sustain livestock grazing. Further assessment of the effects of flooding and excessive draining over African stargrass should be performed to further understand its suitability in the watershed EcoZones. Lastly, the same EcoZones that are not suitable for rice are also not suitable for livestock grazing (Figures 8.9). Page │ 45
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico Candelaria Watershed Land Suitability LIVESTOCK GRAZING 5 Legend Suitable (S1) Not Suitable (N2) Guatemala 0 10,000 20,000 30,000 Meters Figure 8.9 – Land Suitability Assessment: Livestock grazing (African stargrass) The final Land Suitability Assessment feature which shows the optimal agricultural crop for each EcoZone was prepared according to the most suitable crop for each EcoZone (Figure 8.10). This map of the watershed shows the most suitable crop per EcoZone. It demonstrates that the northern EcoZones of the discharge area (to the Gulf of Mexico), most of the north-east EcoZones and the majority of the floodplain EcoZones are not suitable for any crop growth. Sorghum can be grown in the north-central EcoZones and few other EcoZones that are to the west of the north-central area of the watershed. Also few fragmented EcoZones, mostly to the east, throughout the Candelaria Watershed (Figure 8.10). Between 15 and 20 small split EcoZones in the south and south-eastern parts can have both rice and sorghum grown there. All the other EcoZones throughout the watershed, which makes the chief number of EcoZones, and are mainly in the north-west, central and southern EcoZones can have rice grown in them (Figure 8.10). Page │ 46
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico Candelaria Watershed Land Suitability OPTIMAL AGRICULTURAL CROP 5 Legend Rice Rice or Sorghum Sorghum Not Suitable Guatemala 0 10,000 20,000 30,000 Meters Figure 8.10 – Land Suitability Assessment: Optimal Agricultural Crops Page │ 47
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico 9.0 LAND DEGRADATION ASSESSMENT 9.1 Remote Sensing Applications Natural colour composite satellite photographs were retrieved for the watershed area for the years 1990, 2000 and 2005 from Landsat-4 and Landsat-7 satellites (Fig. 5). The green vegetation observed in 1990 progressively decreases from 1990 to 2000 to 2005, where most of the green vegetation is replaced with reddish-brown land cover (Fig. 5). Normalized Difference Vegetation Index (NDVI) is a vegetative productivity indicator that analyzes remote sensing data. The NDVI measures the amount of near-infrared (NIR) that is reflected from an area, as a proportion of total reflectance of the electromagnetic spectrum (Hamel et al. 2009), where: NDVI = (NIR – RED) / (NIR + RED) Reflected light from vegetation reflects a higher near-infrared radiation than red radiation, allowing satellite imagery to estimate land cover (Hamel et al. 2009). The NDVI used for the Candelaria watershed area from 1990-2000-2005 illustrates that the change in colour composite satellite photographs is due to decrease in vegetative productivity (Fig. 6). The index ranges from -1 to 1; negative values indicate lack of vegetative productivity and positive values indicating higher vegetative productivity, displayed as blue for negative and pink for positive (Fig. 6). Page │ 48
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico 1990 2000 2005 Fig. 5 Landsat-4 and Landsat-7 satellite photographs of the Candelaria watershed area for the years 1990, 2000 and 2005. 1990 2000 2005 Fig. 6 NDVI used for Landsat-4 and Landsat-7 satellite photographs of the Candelaria watershed. Page │ 49
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico 10.0 CONCLUSIONS Slash-and-burn agricultural or shifting cultivation is practiced by approximately 300 to 500 million people on more than 500 hectares, mostly in the tropics (Laird, No Date). This method is very common amongst indigenous and small-holder communities in the Yucatan Peninsula in Mexico. The slash-and-burn system is commonly used by individual, poor farmers when they develop agricultural land for subsistence farming and to supply cash goods to a local market. These farmers are highly dependent on their lands and as a result, most often over work their land resulting in major losses to soil fertility. Furthermore, increases in population have also created a large pressure on these farmers to produce larger crops yields. These issues have resulted in agricultural lands to be completely stripped of nutrients and have lead farmers to abandon their land. The deforestation of lush tropical forests that are large carbon pools has been an on-going for the creation of fertile agricultural. This type of agricultural technique is often and interchangeably referred to as shifting cultivation and slash-and-burn agriculture. Slash-and-burn is common among Mexican farmers in the Yucatan peninsula in Mexico. Slash-and-burn agriculture is a highly destructive practice that is most often carried out by extremely impoverished populations and is one of the leading drivers of tropical deforestation. Deforestation is one the greatest issues today in dealing with climate change. Not only does deforestation lead to a massive loss of species and biodiversity, it is estimated to release approximately 20% of annual anthropogenic emissions at some 2 Gigatons (Gt) per year (Uryu et al, 2008). The current question is how to provide nutrients to the soil for plant uptake enough to stabilize cultivation for an undetermined number of years. The change in vegetative cover over time is consistent with the population growth and increased urbanization in the area, as well as increased land-clearing for cultivation. The population size of the state of Campeche was 535,185 inhabitants in 1990 and increased to 690,689 in 2000 and finally to 754, 730 inhabitants in 2005 (INEGI, 2006) (Fig. 7). Considering the observation that the population in Campeche gained 219,545 inhabitants from 1990-2005, at an approximate increase rate of 14,636 persons per year, the increasing land use is expected due to demands of food security. Page │ 50
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico 800,000 Population Size 700,000 600,000 500,000 400,000 300,000 200,000 100,000 0 1930 1940 1950 1960 1970 Year 1980 1990 2000 Fig. 7 Population increase in the state of Campeche, Mexico from 1930-2000. Data retrieved from INEGI (2006). The Rio Candelaria discharges into the Terminos Lagoon, currently a protected area that is the most important bird wintering area in the Gulf of Mexico (Robadue et al. 2004). The Lagoon reserve area has 1468 faunal species, 89 of which are threatened and 132 are of important commercial value (Robadue et al. 2004). The Lagoon is an important nursery and feeding area for commercial fish and shrimp populations and Campeche Sound contributes approximately 34% of Mexico’s total fishery yield (Robadue et al. 2004). The Rio Candelaria makes up 16% of the Terminos Lagoon’s watershed influences, making it an important freshwater source into the eastern part of the Lagoon (Robadue et al. 2004). Environmental concerns in the Terminos Lagoon include oil spills from offshore wells, inadequate treatment of wastewater in the city of Carmen, and illegal fishing in the reserve areas (Robadue et al. 2004). Mangroves are especially affected by increased sedimentation into the Lagoon as well as fragmentation caused by decreased water flow by highways and other debris like fishing gear, which effectively cuts off their water circulation cycle and leads to further shore erosion (Robadue et al. 2004). Rice production in the Candelaria watershed alters discharge flow into the Terminos Lagoon and slash-and-burn agriculture increases erosion and sedimentation of the river system (Robadue et al. 2004). Page │ 51
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico 11.0 RECOMMENDATIONS Continuation of slash-and-burn is highly problematic for several reasons. One of the main reasons is that slash-and-burn agriculture is not sustainable due to the pressures of population increases, forests resources and changing precipitation patterns. The changes due to global climate change are a threat to tropical forests with massive forest fires possibly which could have the potential to transform them into vast savannahs (Laird, No Date). It is obvious that slash-and-burn agriculture is no longer sustainable under these new emerging circumstances of population pressure and global climate change. In the study “Low Input Cropping for Acid Soils of the Humid Tropics” by Sanchez et al. (1987), they argued that, “Stable alternatives to shifting cultivation are needed for humid tropical locations where increasing demographic pressure no longer permits traditional slash-and-burn agriculture.” Recently, slash-and-char agriculture has been suggested as a critical alternative to slash-and-burn agriculture. Biochar combined with crop residues (organic matter & manures) could increase the carbon and nutrient pools in the soil to achieve continuous cropping and avoid shifting cultivation which results in emissions from burning, forest degradation & deforestation. Deforestation could be minimized by offering farmers in the farming communities of Candelaria an alternate to traditional slash-andburn agriculture. The current agricultural practice of slash-and-burn agriculture is used to provide nutrients to the soil for crop production. Therefore, the current question is how to provide nutrients to the soil for plant uptake enough to stabilize cultivation for an undetermined number of years. Biochar combined with crop residues (organic matter & manures) could increase the carbon and nutrient pools in the soil to achieve continuous cropping and avoid shifting cultivation which results in emissions from burning, forest degradation & deforestation. “Slash-and-char” has been proposed as an alternative to slash-and-burn agriculture providing a number of ecological, economic and social benefits. Slash-and-char systems have the potential management technique for maintaining and improving the sustainability of indigenous agro-ecological systems in Yucatan, Mexico. Currently, there is a fair amount of research that exists which suggests biochar applications to soil could have multiple beneficial effects, particularly in the tropics or in areas with already low soil quality. Below the ecological benefits in regards to biochar as a soil amendment and for carbon sequestration is discuss along with social and economic benefits. Slash-and-char agriculture recently has been suggested as a critical alternative to slash-and-burn agriculture. This management strategy will strive to change the agriculture industry from carbon-positive to carbon-negative, which will potentially provide significant benefits to soils and to livelihoods of local farm Page │ 52
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico communities through the emerging carbon market (Laird, No Date). Below is a summary of most of the potential benefits of biochar agriculture management. Summary of potential benefits of biochar soil management • Improved soil fertility and crop yields • Increased fertilizer efficiency use • Improved water retention, aeration and soil structure • Higher cation exchange capacity (CEC) and less nutrient runoff • Clean and efficient biomass energy production from crop residues and forest debris • Combined heat, power, and refrigeration opportunities from pyrolysis • Leads to net sequestration of carbon from the atmosphere to the soil thereby increasing soil organic carbon (SOC) • Greater on-farm profitability • Can be financed through carbon markets and carbon offsets • Decreased nitrous oxide and methane emissions from soils • Provides powerful tool for reversing desertification • Provides alternative for slash-and-burn agriculture • Can work as component of reforestation efforts • Can produce electricity, bio-oils, and/or hydrogen fuels • Can use wide variety of feedstock including crop residues such as wheat and corn straw, poultry litter, cow manure, forest debris, and other farm-based biomass resources • Acts as a liming agent to reduce acidity of soils (Laird, No Date) 12.0 REFERENCES Benke R, Cushing C. (2005) Rivers of North America. Elsevier Academic Press. Page 1050-1054. Ecocrop. 2010. Food and Agriculture Organization (FAO). Available online: [http://ecocrop.fao.org/ecocrop/srv/en/home]. Accessed: April 25, 2010. Laird D A. (No Date) Farm. USDA National Soil Tilth Laboratory. Biochar Farms: Resources for sustainable use of biochar in agriculture. [Online]. <http://biocharfarms.org/farming/>. Accessed 28 March 2010. Page │ 53
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico N. J. K. (2006) Maya. [Online]. <http://www.solarnavigator.net/history/maya.htm>. Accessed 27 April 2010. Pidwirny, M. (2006). Stream Morphometry. Fundamentals of Physical Geography, 2nd Edition. [Online]. <http://www.physicalgeography.net/fundamentals/10ab.html>. Accessed 25 April 2010. Ponce-Hernandez, R. 2010. Laboratory outlines 1-6 and lecture slides 1-12. ERSC-GEOG 4640H – Integrated Watershed Management. Trent University, Peterborough, Ontario. Ponce-Hernandez, R. and F. Beernart. 1991a. Land Evaluation Manual (I). FAO Project: Mozambique. Rome, Italy. Ponce-Hernandez, R. and F. Beernart. 1991b. Crop Requirements Manual (II). FAO Project: Mozambique. Rome, Italy. Serrano, L R. (2004) Desertification Indicator System for Mediterranean Europe. Desertlinks. [Online]. <http://www.unibas.it/desertnet/dis4me/indicator_descriptions/drainage_ density.htm>. Accessed 25 April 2010. Uryu, Y. et al. (2008) Deforestation, Forest Degradation, Biodiversity Loss and CO2 Emission in Riau, Sumatra, Indonesia.WWF Indonesia Technical Report, Jakarta, Indonesia. FAO. Smith, M. CropWat 4 Windows Version 4.3. Land and Water Development Division. Food and Agriculture Organization of the United Nations (FAO). Rome, Italy. Available online at: [http://www.fao.org/nr/water/infores_databases_cropwat.html] FAO. Smith, M. ClimWat 2.0. Land and Water Development Division. Food and Agriculture Organization of the United Nations (FAO). Rome, Italy. Available online at: [http://www.fao.org/nr/water/infores_databases_climwat.html] INEGI / Direccion General de Geografia. Villa del Carbon, E14A28 [map]. 2nd Edition. 1:50,000. Mexico 1:50,000. Aguascalientes, AGS: Instituto Nacional de Estadistica, Geografia e Informatica, 2003. SMN (1961-1990). Servicio Meteorológico Nacional. Mexico City. Available online at: [http://smn.cna.gob.mx/climatologia/normales/estacion/catalogos/cat_camp.html] Zhang Y., Liu C., Tang Y. and Yang Y. 2007. Trends in pan evaporation and reference and actual evapotranspiration across the Tibetan Plateau. Journal of Geophysical Research 112: 12 pp. Hamel S., Garel M., Festa-Bianchet M., Gaillard J.-M. and Côté S.D. 2009. Spring Normalized Difference Vegetation Index (NDVI) predicts annual variation in timing of peak faecal crude protein in mountain ungulates. INEGI. Instituto Nacional de Estadistica y Geografia e Informatica. Población total según sexo, 19302005 en la entidad. 2006. Censos de Población y Vivienda, 1930 – INEGI. Conteos de Page │ 54
  • Integrated Watershed Management Plan: Candelaria Watershed, Campeche, Mexico Población y Vivienda, 1995 y 2005. Available online at: [http://www.inegi.org.mx/inegi/default.aspx?s=est&c=4326&e=04]. Robadue D., Oczkowski A., Calderon R.,Bach L. and Cepeda M.F. 2004. Characterization of the region of the Terminos Lagoon: Campeche, Mexico: Draft for Discussion. Narragansett, RI: Coastal Resources Center, University of Rhode Island. PLUS Calderon, R. (2004). Draft 1 Site Profile: The Laguna De Términos, Mexico. Corpus Christi, TX: The Nature Conservancy. Page │ 55