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Water harvesting

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  10. 10. Accessibility View text version Categories Technology Design Upload Details Uploaded via SlideShare as Adobe PDF Usage Rights Report content Flag as inappropriate File a copyright complaint No comments yet Subscribe to commentsPost Comment 3 Likes tanmay patil 1 month ago Priyesh Sengar, IAS FACULTY at self employed 5 months ago tusharjitu 7 months ago India; Rain Water Harvesting, Conservation and Management Strategies for Urban and Rural SectorsDocument Transcript 1. National Seminar on Rainwater Harvesting and Water Management 11-12 Nov. 2006, Nagpur STATE OF THE ART LECTURE 1. Rain Water Harvesting, Conservation and Management Strategies for Urban and Rural Sectors * Dr. R. K. Sivanappan1. Introduction Nabateans and other people of the Middle east. Water is essential for all life and used in many While the early water harvesting techniques useddifferent ways, It is also a part of the larger natural materials, 20th century technology has madeecosystem in which the reproduction of the bio it possible to use artificial means for increasing runoffdiversity depends. Fresh water scarcity is not limited from precipitation.to the arid climate regions only, but in areas with Evenari and his colleagues of Israel havegood supply the access of safe water is becoming described water harvesting system in the Negvecritical problem. Lack of water is caused by low desert. The system involved clearing hill sides towater storage capacity, low infiltration, larger inter smooth the soil and increase runoff and then buildingannual and annual
  11. 11. fluctuations of precipitation (due contour ditches to collect the water and carry it toto monsoonic rains) and high evaporation demand. low lying fields where the water was used to irrigate The term water harvesting was probably used crops. By the time of the Roman Empire, these runofffirst by Geddes of the University of Sydney. He farms had evolved into relatively sophisticateddefined as the collection and storage of any form of systems.water either runoff or creek flow for irrigation use. The next significant development was theMeyer‘s of USDA, USA has defined it as the construction of roaded catchments as described bypractice of collecting water from an area treated to the public works Department of Western Australiaincrease runoff from rainfall. Recently Currier ,USA in 1956. They are so called because the soil is gradedhas defined it as the process of collecting natural into ditches. These ditches convey the collectedprecipitation from prepared watershed for beneficial water to a storage reservoir. Lauritzan, USA hasuse. Now a days water harvesting has become a done pioneering work in evaluating plastic andgeneral term for collecting and storing runoff water artificial rubber membranes for the construction ofor creek flow ,resulting from rain in soil profile and catchments and reservoirs during 1950‘s. Inreservoirs both over surface /under surface. 1959,Mayer of water conservation laboratory, USAPreviously this was used for arid and semi arid areas, began to investigate materials that caused soil tobut recently their use has been extended to sub humid become hydrophobic or water repellent. Thenand humid regions too. In India water harvesting gradually expanded to include sprayable asphaltmeans utilizing the erratic monsoon rain for raising compounds, plastic and metal films bounded to thegood crops in dry tracks and conserve the excess soil compaction and dispersion and asphalt fiber glassrunoff water for drinking and for recharging membranes. Early 1960, research programmes inpurposes. water harvesting were also initiated in Israel by Hillal and at the University of Arizana by Gluff. Hillal‘s2. History of Rain Water Harvesting work related primarily to soil smoothing and runoff Water harvesting like many techniques in use farming. Cluff has done a considerable amount oftoday is not new. It is practiced as early as 4500 work on the use of soil sealing with sodium salt andB.C. by the people of Ur and also latest by the on ground covered with plastic membranes. * International Consultant in Water Resources & Irrigation, No:14, Bharathi park, 4th Cross Road, Coimbatore 641 043 1 2. Water harvesting was practiced more than These rainwater are used for all labs, which require1000 years back in South India, by way of pure and good quality of water. In the same wayconstruction of irrigation tank, ooranis, temple tanks, the rainwater falling on the terrace in all the buildingfarm ponds etc, but the research in India on this constructed subsequently are collected and storedsubject is of recent one. Work is taken up at in the underground masonry tanks Even the surfaceICRISAT, Hyderabad, Central arid Zone Research water flowing in the Nalla‘s in the campus are alsoInstitute, Jodhpur, Central Research Institute for diverted by providing obstructions, to the open wellsdryland Agriculture (CRIDA), Hyderabad, State to recharge ground water.Agricultural Universities and other dry land research Hence Rainwater harvesting is as old ascenters throughout India. civilization and practiced continuously in different In Pakistan, in the mountainous and dry ways for different purposes in the world The onlyprovince of Balukhistan, bunds are constructed thing is that it has not been done systematically in allacross the slopes to force the runoff to infiltrate. In places. Need has come to harvest the rainwaterChina, with its vast population is actively promoting including roof water to solve the water problemsrain and stream water harvesting. One very old but everywhere not only in the arid but also in the humidstill common flood diversion technique is called region.‗Warping‘ (harvesting water as well as sediment). When water harvesting technique are used 3. Need for Rain Water Harvestingfor runoff farming, the storage reservoir will be soil Water is a becoming a scarce commodity anditself, but when the water is to be used for livestock, it is considered as a liquid gold in this part of thesupplementary irrigation or human consumption, a country (especially in Coimbatore, Erode, Salemstorage facility of some kind will have to be Districts of Tamil Nadu). The demand of water isproduced. In countries where land is abundant, water also increasing day by day not only for Agriculture,harvesting involves; harvesting or reaping the entire but also for household and Industrial purposes. It israinwater, store it and utilize it for various purposes. estimated that water need for drinking and otherIn India, it is not possible to use the land area only to municipal uses will be increased from 3.3 MHm toharvest water and hence water harvesting means 7.00 MHm in 2020/25. Similarly the demand of wateruse the rain water at the place where it falls to the for industries will be increased by 4 fold i.e. frommaximum and the excess water is collected and 3.0 MHm ti 12.00 MHm during this period At theagain reused in the same area. Therefore the same time more area should be brought undermeaning of water harvesting is different in different irrigation to feed the escalating population of thearea/ countries. The methods explained above are country, which also needs more water. But we areused for both agriculture and to increase the ground not going to get one litre more water than we get atwater availability. present though the demand is alarming. The water harvesting for household and for The perennial rivers are becoming dry andrecharging purposes are also in existence for long ground water table is depleting in most of the areas.years in the world. During rainy days, the people in In Coimbatore, the depletion is about 30-50m in thethe villages used to collect the roof water in the last 30-40 years. Country is facing floods and droughtvessels and use the same for household purposes in the same year in many states. This is because, noincluding drinking. In South East Asian countries concrete action was taken to conserve, harvest andpeople used to collect the roof water ( thatched roof manage the rain water efficiently.by providing gutters) by placing 4 big earthern drums The rainfall is abundant in the world and alsoin 4 corners of their houses. They use this water for in India. But it is not evenly distributed in all places.all household purposes and if it is exhausted only India being the monsoonic country, the rain falls onlythey will go for well water. The main building of the for 3 to 4 months in a year with high intensity, whichAgricultural College at Coimbatore was constructed results more runoff and soil erosion. Total rain occurs100 years ago and they have collected all the roof only in about 100 hours out of 8760 hours in a year.water by pipes and stored in a big under ground It also erratic and fails once in 3 or 4 years. This ismasonry storage tanks by the sides of the building. very common in many parts of the country. 2
  12. 12. 3. The availability of water in the world, in India hard rock in Tamil Nadu. Further the porosity of theand in Tamil Nadu is given below with rainfall. rock is only about 3%. The natural recharge of rainwater in this region is only about 8 -12%, which Places Rainfall Population Availability of is very minimal. Therefore there is an urgent need in mm Water/Person/Yr to take up the artificial recharge of the rain for which M 3 /P/Year water harvesting and water conservation structures World 840 6 Billion 700 are to be build up in large scale. The rainfall in coastal area is more than 1200 mm (Chennai) still; drinking India 1150 1.0 Billion 2200 water is a problem in almost every year. This is Tamil Nadu 925 62.5 Million 750 because the entire rainwater is collected in masonry drains (from houses, streets/roads etc) are taken to If the availability of water is 1700 M3/p/y, the sea instead of taking into the ground waterthere will be occasional water stress, and if it is less aquifers or in surface reservoirs by pumping if needthan 1000 M3/p/y, it is under water scarcity condition. be. The ground water available can be used duringThough India is not under water stress conditions summer and make the aquifer empty so that thebut Tamil Nadu state is already under water scarcity rainwater can be put into the aquifers during rainycondition, but there is no need for panic since it is period by suitable water harvesting measures.possible to manage this condition as in the case of All the above details indicate the need forIsrael where the availability is only about 450 M3/p/ water harvesting measures in urban and rural areay, by means of water harvesting, water conservation for the use of Agriculture, drinking and otherand water management. purposes. Water scarcity / stress is not limited to thearid regions; only but also occurring in high rainfall 4. Methods of Water Harvesting in Rural andareas also. Chirapunji gets more than 11,000mm of Urban Areasaverage annual rainfall but face drinking water There are different / various system of waterproblem before monsoon commences whereas in harvesting depending upon the source of waterRalegoan Siddhi, in Maharastra there is no water supply and places as classified below.scarcity problem though the annual average rainfall a) In situ Rainwater harvestingis only about 450mm. Hence to mitigate water • Bunding and terracing.problem / drought etc, there is an urgent need to • Vegetative / stone contour barriers.follow our ancestral way of water harvesting and • Contour trenching.the latest technologies adopted in Soil and waterconservation measures on watershed basis including • Contour stone walls.roof water harvesting etc which are described in • Contour farming.detail below. • Micro catchments. The Theme paper on Water vision 2050 of • Tie ridging methodsIndia, prepared by Indian Water Resources • Farm ponds.Society(IWRS) has indicated that a storage of 60 b) Direct surface runoff harvestingMHm is necessary to meet tbne demand of water • Roof water collectionfor irrigation, drinking and other purposes. But the • Dug out ponds / storage tankspresent live storage of all reservoirs put together is • Tankasequivalent of about 17.5 MHm which is less than10% of the annual flow in the rivers in the country. • KundisThe projects under contruction (7.5 MHm) and those • Ooraniscontemplated (13 MHm) are added, it comes only • Temple tanks37.50 MHm and hence we have to go a long way in • Diversion bundswater harvesting to build up storage structures in • Water spreadingorder to store about 60 MHm. c) Stream flow / runoff harvesting More than 75% of the areas comes under • Nalla bunding 3 4. • Gully control structures municipalities / corporation without any difficulty to • Check dams – Temporary some extent. Permanent To sum up the following types of Water • Silt detension tanks Harvesting System for different uses can be • Percolation ponds implemented in different parts of the country.d) Sub surface flow harvesting • Sub surface dams No. Region Types of Water Use • Diaphragm damse) Micro catchment‘s / watershed 1 Arid Artificial catchments Drinking • Inter terrace / inter plot water harvesting plains to capture rainfall (tankas or kundis in • Conservation bench terrace Rajasthan)f) Runoff inducement by surface treatment • Roaded catchments Tanks or talabs in Drinking • Use of cover materials – Aluminum foils, Rajasthan to capture and Plastic sheet, bentonite, Rubber, etc surface runoff irrigation • Using chemicals for water proofing, water repellent etc. to get more run off water. Embankments / Irrigation obstructions across water & also A comprehensive watershed development on drainage / Nalla to for rechargingwatershed basisincluding water harvesting structures capture surface runoffare given in the figure 1. 2 Semi Tanks / Ponds/Eri to Irrigation Arid capture surface runoff water and5. Plan of Action for Rainwater Harvesting places and also chains of drinking water As stated early, rainwater harvesting is as old tanks called cascade. throughas civilization and is practiced in many countries recharge ofincluding India from time immemorable. But ground watergovernment and people remember this only whenwater is not available even for drinking purposes. 3. Flood Mud embankment IrrigationThere is no use of spending huge sum of money plains which may be water and breached during the drinking waterwhen we notice the water scarcity for drinking, floods. throughindustry and agriculture. These activities / structure rechargingshould be taken / constructed before the rainy season ground waterso that the rain water which goes as runoff outsidethe sub watershed / city limits can be collected and 4 Hill and Diverted stream flows Irrigationused directly or by recharging into the ground. Mountain Jammu, M.P., waterGovernment is undertaking the wasteland / region Maharastrawatershed development programs, but not done in acomprehensive / integrated manner / holistic 6. Case Study In Water Harvestingsaturating the watershed in all water harvesting There are numerous case studies available inmeasures. Hence there is a need to take up water harvesting both in Rural and Urban sectors.watershed development programmes – mainly water In Rural areas it is Soil and Water conservationharvesting measures in a scientific and systematic measures taken on watershed basis to conserve andmanner. augment ground water. In the urban sector, it is The government of Tamil Nadu has laid mostly roof water harvesting for direct use andcondition that in any building construction, water recharging the ground water and also collecting ofharvesting work should be included and executed, surface runoff from pavements / roads andbut in practice, it is not perfect. The authorities recharging it into the ground through recharge pitsconcerned should monitor the programme so that or using abandoned / existing wells. The followingthe drinking water problem can be solved in all are the places where rain water / roof water 4 5. harvesting has been implemented in a successful the rain water harvesting to their Industry premises.manner. If the above measures are implemented in1. Rural areas Rural and Urban areas, the drought in rural areasa. Ralegoan Siddhi in Maharastra state and drinking water problem in Urban and Ruralb. Lakshman Nagar and Varisai Nadu inTheni population can be solved to some extent. The people, Dt., Tamil Nadu. NGO, and Government should joint together andc. Alankulam Taluk in
  13. 13. Tirunelveli Dt., Tamil Nadu. implement the rain water harvesting in a big way ind. Aravari watershed in Alwar Dt., of Rajasthan. all places in the years to come to solve water scarcitye. Maheshwaram watershed in Andhra Pradesh. problem in the country.f. Kapilnalla watershed in Karnataka 7. Conclusions2. Urban Sectors It is very important to make water everybody‘sMostly the roof water harvesting measures are taken business. It means a role for everybody with respectup. to water. Every household and community has toa. India become involved in the provision of water and ini. Tamil Nadu Agricultural University, Coimbatore, the protection of water resources. Make water the all main buildings. subject of a people‘s movement. It means theii. PRICOL, Periyanaickenpalayam (Industry empowerment of our Urban and Rural community, Building), Coimbatore i.e., to manage their own affairs with the state playingiii. TWAD Board / office and PWD office at a critical supportive role. Chennai. Further involving people will give the peopleiv. Numerous Apartment buildings in Chennai. greater ownership over the water project includingv. Sundaram and Clayton Ltd, Padi, Chennai – watershed development, Soil and Water (Industry buildings) conservation and water harvesting will go a longvi. TVS training schoool at Vanagaran, Chennai way towards reducing misuse of government funds.vii. Rastrapathi Bhavan, Delhi. It will also develop the ownership (own water supplyviii. Center of science and environment building at systems), they will also take good care of them. In Delhi. this way it is possible to solve water problems facingix. Institute of economic growth, New Delhi. the county in the 21st century.b. Foreign Countries Referencesi. Thailand – Many houses including thatched • Ake Nilsson, Ground water dams for small-scale water houses in villages. supply, IT publication, 1988.ii. Japan – office complex. • Center for science and environment. A water-harvesting manual, Delhi 2001.iii. Germany – office buildings. • Center for Science and Environment – Making wateriv. Singapore – office buildings. everybody‘s business, New Delhi, 2001. • Chitale M.A., A blue revolution, Bhavans Book Rules and regulations have been framed for University, Pune 2000.Rain Water Harvesting in all corporation, • CII, Rainwter harvesting – A guide, New Delhi 2000.municipalities and panchayat unions in Tamil Nadu. • Rajiv Gandhi, National Drinking water missionsThe Gujarat government has issued a general Handbook on Rainwater harvesting, Government of India, New Delhi, 1998.resolution for the effort that no new construction • Sivanappan, R.K., Soil and Water Conservation andwould be allowed if it does not have provision for Water harvesting, Tamil Nadu Afforestation project,roof top rainwater harvesting. This would be valid Chennai, 1999.in all 143 municipalities and 6 urban development • Sivanappan, R.K. Water harvesting, ICCI, Coimbatoreauthorities in the state. It is heartening to note that 2001.Confederation of Indian Industries (CII) and • Stockholm water Symposium – ‗Water harvesting‘ Stockholm, Aug 1998.Federation of Indian Chambers of Commerce and • Verma HN & Tiwan KN current status and Prospects ofIndustries (FICCI) have taken action to implement Rain Water Harvesting, NIH, Roorkee, 1995. 5 6. National Seminar on Rainwater Harvesting and Water Management 11-12 Nov. 2006, Nagpur 2. Water Issues and Related Concerns * Prof. (Mrs.) Vijaya Agarwal ** Prof. (Dr.) J. H. Agarwal ABSTRACT By 2025, world population will be 8 billion – water will become scarcer. Global farming accounts for 70% of water use, while only 17% of farmland is irrigated and it provides only 40% (estimated) of world‘s food. Water application losses in irrigation are quite high – almost 40 % of the total irrigation water is lost. Per capita irrigated agricultural land is declining – main reason shortage of water. Water table is falling steadily in intensive farming regions. People and ecosystems are under threat from persistent chemicals like pesticides, fertilizers and heavy metals in waters. There are no serious efforts to gain water by practices like rainwater harvesting, watersheds and mini-ponds, reuse and recycling of waste water. It is said there is enough freshwater in world – however, it is not always available in the right place or right form. The problem is mainly of access, distribution, and optimum utilization. The paper discusses related concerns and outlines what need to be done. Key words : Fresh water, harvesting and conservation of water, water reuse, water management in agro-ecosystems, electronics and IT based devices.1.0 WHAT NEED TO BE DONE? – Some • Water conservation and higher efficiencies forsuggestions waterconveyance, water-application and water-use. Scientific management of water by1.1 Ground Water Recharge, Reuse, and making use of electronics and IT based aidsEfficient Systems like soil-moisture measurements.• Watersheds, Check dams, Roof water • Participation of women in conservation of harvesting (should be made compulsory and water. mandatory), India uses around 15% of rain • Competent, knowledgeable and experienced water while Israel almost 100% (see personnel to be involved in management of Appendix). water related activities and balanced• Efficient irrigation systems: Sprinkler, drip, distribution of water. trickle (macro and micro irrigation). Drip irrigation cuts water use by between 30% and 1.2 Water needs of plants 70% , increases crop yield by between 20% Agriculture accounts for 70% of fresh water and 90%, compared with traditional irrigation. use. It requires as much as 2000 litres of water to• Sequential water use : Reuse, recovery and grow 1 kg of rice. Water (with elements H + O) is recycling of waste waters. a vital component for crop growth. Plants need• Switching to less water-dependent crops. water for: * Selection Grade Assistant Professor (Electrical Engineering), Department of Agricultural Structures and Environmental Engineering, College of Agricultural Engineering, Jawaharlal Nehru Agricultural University, Krishi Nagar, Adhartal P.O., Jabalpur 482 004, Email : vijaya_agarwal@gmail.com Phone : 0761 – 2681820 ** Retired Director Instrumentation & Project Coordinator UNDP-GOI-MAEP, JNAU, G-83 Krishi Nagar, Adhartal P.O., Jabalpur 482 004 Email : jhagarwal@sancharnet.in Phone : 0761 – 2680400 6 7. • Temperature regulation, web site: www.irrometer.com).• Photosynthesis, • Tensiometric principle, indicates the amount of• Transport of nutrients from soil to plant, and moisture available to plants.• Transport of assimilates from plant parts to the • Direct display of moisture. produce location. • Automatic control of irrigation systems.1.3 Excess water harmful 4. Watermark Soil Moisture Sensor – 200SS Excess water to crop is harmful. It causes/ (Irrometer Company, USA,results in : web site : www.irrometer.com ).• Spoilage of soil-health, salinity built up. • Solid state, electrical resistance type.• Loss of nutrients due to excessive leaching. • Available with meter, electronic control unit.• Contamination of surface and ground water. • Low cost.• No proportionate increase in yield, and wastage of water and energy. 5. Sentek Soil Moisture Probes – EnviroSCAN, EnviroSMART, EasyAG and Diviner 20002.0 SOIL-MOISTURE MEASUREMENT (Sentek,
  14. 14. Australia,SYSTEMS web site : www.sentek.com.au ). A variety of electronics and microprocessor- • Electrical capacitance principle, continuousbased devices for soil-moisture measurement are measurement of soil moisture over multipleavailable for scientific water management in agro- depths in root-zone.ecosystems. Some of the devices are based on • Easy installation, data download options forelectrical impedance, infrared thermometry and retrieving data in the field or remotely.time-domain reflectometry. Salient features of five • Provides information on crop water use andsuch devices are given below: water management in root-zone, facilitates1. Gro-Point GP-ERS Moisture Sensor and decisions on how much and when to irrigate. Irrigation Management System (ESI Environment Sensors Inc., Canada, These devices should be used for scientific web site : www.esica.com ). management of water in agro-ecosystems to make• Soil moisture range: 5 – 50 % (volumetric) +/- efficient use of water and to minimize problems like 1%. water logging, salinity built up, non-point• Rechargeable battery or mains operated. contamination (see Appendix , Fig. 2 (a), (b), (c)• Available with hand-held display or with data and (d) for photographs of some soil-moisture logger. devices).• Intelligent Irrigation System, with a set of sensors, computer, 3.0 IT ENABLED SUPPORT SYSTEMS software and irrigation controller. FOR OPTIMUM UTILIZATION Use of Crop Simulation Models, Weather2. Moisture-Point, Multi-Probe Sensor MP-917 data and Knowledge Base(s): (ESI Environment Sensors Inc., Canada, • To select appropriate crop and crop variety web site: www.esica.com ). suitable to agro-climatic pattern, and switch to• Soil moisture range : 0 – 50 % (volumetric) +/- less waterdependent crops. 1.5%. • To decide about the date of sowing, duration of• A single probe gives moisture profile. crop.• Rechargeable battery or mains operated. • To decide about the irrigation inputs to crop by• LCD display or datalogger or RS232 with monitoring soil-moisture and crop-water stress, PC. to decide when and how much to irrigate, and to optimize utilization of water by using3. Irrometer-Tensiometer Probe (Irrometer efficient systems like sprinkler, drip and trickle Company, USA, irrigation. 7 8. • To apply fertilizer to crops through irrigation Population Reports, Series M, No. 14. water by computer-controlled fertigation Population Information Program, Johns Hopkins techniques. School of Public Health, Baltimore, December• To adopt controlled environment farming 1997. wherever easily feasible: This provides • United States Department of Agriculture. ARS monitoring and control of lighting, humidity, National Program # 201 on Water Quality and temperature, CO2 level, irrigation, nutrients Management : Component I – Agricultural supply, chemical treatments, etc. watershed management, Component II –• To adopt a GIS coupled soil-water-balance Irrigation and drainage management, computation system to calculate the available Component III – Water quality protection and residual soil-moisture for its better utilization. management, 1998 – ongoing. < www.nps.ars.usda.gov >4.0 CONCLUDING REMARKS • Li, F., S. Cook, G. T. Geballe and W. R. Water is a very valuable resource. There are Burch. Rainwater Harvesting Agriculture: Anno serious efforts to gain water by practices like integrated system for water management onrainwater harvesting, watersheds and mini-ponds. rainfed land in China‘s semiarid areas, AMBIORainwater harvesting should be made mandatory. – Journal of Human Environment, Vol. 29, IssueSequential water use (reuse, recovery and recycling 8, December 2000, pp. 477-483.of waste waters) should be planned wherever • Gleick, P. H. The World‘s Water 2000 - 2001:possible so that the load on fresh water can be The Biennial Report on Freshwater Resources.reduced. Water‘s presence in agro-ecosystems Island Press, Washington, DC, 2000.should be treated on a holistic approach, and by • Rijsberman, F. and D. Molden. Balancing wateremploying scientific management tools it should be uses: water for food and water for naturejudiciously used. For agriculture, an integrated (Thematic background paper), Internationalwater management practice consisting of three main Conference on Freshwater, Bonn, Germany, 3-components – rain water harvesting, water-saving 7 December 2001.microirrigation, and highly efficient crop • Smajstrla, A.G., B.J. Boman, D.Z. Haman, F.T.production – should be adopted. Conservation of Izuno, D.J. Pitts and F.S. Zazueta. Basicwater should be taken as a way of life and widely irrigation scheduling in Florida < http://adopted. edis.ifas.ufl.edu/AE111 > Bulletin # 249, Agricultural and Biological EngineeringSELECTED READING Department, Cooperative Extension Service,• Goodchild, M.F., B.O. Parks and L.T. Steyaert Institute of Food and Agricultural Sciences, (Eds.). Environmental Modelling with GIS. University of Florida, Gainesville, 2002. Oxford University Press, New York, 1993. • Fahimi, F.R., L. Creel and R.M. De Souza.• Berkhoff, J. A Strategy for Managing Water in Finding The Balance: Population and Water the Middle East and North Africa. World Bank, Scarcity in the Middle East and North Africa. Washington, DC, 1994. Population Reference Bureau, Washington, DC,• Bian, F., Z. Sha and W. Hong. An integrated 2002. GIS and knowledge-based decision support • Simonne, E. and G. Hochmuth. Irrigation system in assisting farm-level agronomic scheduling as a means of applying the right decision-making. J. Geogr. Syst., 1995, 3, pp. water amount and monitoring soil moisture for 49-67. vegetable crops grown in Florida in the BMP• SoilMoisture Systems. ESI – Canada < era. Document # HS909, Horticultural Sciences www.esica.com > , Irrometer – USA Department, Cooperative Extension Service, < www.irrometer.com > , Sentek – Australia < Institute of Food and Agricultural Sciences, www.sentek.com.au > . University of Florida, Gainesville, 2003 < http:/• Hinrichsen, D., B. Robey and U. D. /edis.ifas.ufl.edu/HS166 > Upadhyay. Solutions for a Water-Short World. • Rijsberman, F. Sanitation and Water, In: Global 8 9. crises, global solutions (Ed. - B. Lomborg), 2. Soil-Moisture Probes : Cambridge University Press, Cambridge, 2004, 670 p.• IWMI. Beyond more crop per drop (Note prepared by F. Rijsberman and D. Molden for the 4 th World Water Forum, Mexico, 16-22 March 2006), International Water Management Institute, Sri Lanka, Press release, 17 March 2006.APPENDIX1. Rainfall Facts : Percentage of Rainfall (a) Soil-Moisture Probe for moisture measurements in theconsumed to support direct and indirect human root zone of a crop (Sensors are mounted on a screwable insert )uses of water (Source: IWMI, Sri Lanka) System / Uses % of Rainfall Food – irrigation 2 Food – rainfed 4 Domestic & industry 1 Instream ecology 8 Flood runoff 27 Permanent grazing 18 Grasslands 11 Forests & woodlands 17 Arid lands 5 All others 7 Total 100 (b) Tensiometer type soil-moisture probe. (d) Soil-Moisture Probe working on impedance principle. [Note :
  15. 15. Photographs of the probes from websites / product (c) Sentek Soil-Moisture Probe working on literature. Disclaimer: No preference to any particular firm capacitance principle. by the authors]. 9 10. National Seminar on Rainwater Harvesting and Water Management 11-12 Nov. 2006, Nagpur 3. Rainwater Harvesting Techniques * Dr. K. A. Patil ** G. K. Patil ABSTRACT Water is our most precious natural resource and something that most of us take for granted. We are now increasingly becoming aware of the importance of water to our survival and its limited supply. The human beings require water for various purposes. The most part of the earth surface i.e. about 71 % is covered by water. Out of total volume of water available on the surface of the earth 97 % is saline water, 2 % water is in the form of ice and glaciers and only 1 % is fresh and potable water. India is well endowed nations in the world in terms of average annual rainfall. It is unbelievable but it is true that Cherapunji which gets 11000 mm annual rainfall still suffers from serious drinking water shortage. Though India‘s average annual rainfall is 1170 mm; in the deserts of western India it is as low as about 100 mm. Hence, it is necessary to opt for rainwater harvesting measures for fulfillment of water requirement.INTRODUCTION harvesting can play important role for solving the India is one of the developing countries. Due water problems.to faster industrialization and urbanization andincrease in population water demand is increasing WHY RAINWATER HARVESTING?day by day. Rainfall in India is highly irregular. Most Rainwater harvesting means the activity ofof it is concentrated during a few months of the year direct collection of rain water which can beand maximum amount flows away resulting in poor recharged in to the ground water to prevent fall ofrecharge of ground water. There is significant spatial ground water level or storing in surface orimbalance in water resource available and water underground water tank. It is most suited in today‘sdemand. Therefore, it is becoming necessary to context due to following reasons.bring water from distant places increasing the cost 1. It is the most scientific and cost effective wayof conveyance. It is also a common observation that of recharging the ground water and reviving theunderground water table is depleting due to water table.uncontrolled extraction of water. The state of 2. It offers advantage in water quality for bothMaharashtra covers an area of 307,713 square km irrigation and domestic use.and supports a population of 82 million. Over half 3. It provides naturally soft water and containsof this population is in rural area which faces almost no dissolved minerals or salts, arsenicproblems related to water. Conventional sources like and other heavy metals.open well, bore well and piped water supplies have 4. It can be done at individual as well as in afailed due to depleting water tables, poor water community level. This way we can be selfquality and high cost involved in operation and sufficient in terms of domestic watermaintenance. Every year a great amount of water requirements and not just dependent on theis being lost that falls on terraces, all of which finds actions initiated by government or any otherits way to the storm water drains. Rain water local body. * Lecturers in Civil Engineering Dept; Govt. College of Engineering, Aurangabad (M.S.) 431 005 10 11. Collecting rainwater as it falls from the sky 2. Utilization of Rainwater for Recharging Pitseems immensely sensible in areas struggling to Where there is no well or bore well in thecope with potable water needs. Rainwater is one of house, total rainwater falling on the open plot canthe purest sources of water available as it contains be recharged by making recharge pit. Water flowingvery low impurities. Rain water harvesting systems out of the plot can be directed to this pit. This pitcan be adopted where conventional water supply may get filled 10 to 15 times in one monsoon andsystems have failed to meet people‘s needs. can recharge water up to 200 m3. This method is effective in the area where permeability of soil isCOMPONENTS OF RAINWATER more. The capacity of the pit may be taken up to 10HARVESTING STRUCTURE m3. The percolation of water through this pit of theAll rainwater harvesting structures will have three order of 200 m3 per annum is possible. The cost ofbasic components: this structure may come about Rs 7000.1. Catchment area i.e. the surface area utilized for capturing the rainwater. 3. Utilization of Rainwater for Well Recharging2. Collection device, like tanks or cisterns or Rainwater flowing in the farm is diverted to percolation pits used for collecting or holding a water collecting tank of size 6 m x 6 m x 1.5 m the water. near well and a small filter pit of size 1.5 m x 1.5 m3. Conveyance system i.e. the system of pipes or x 0.6m is made at the bottom of large pit. Otherwise percolation pits through which water is suitable pit may be excavated depending upon the transported from the catchment area to the availability of space near well. Fig.2 shows details collection device. regarding recharge of open well by runoff from farm. Filter pit is filled with sand, pebbles larger than 20METHODS OF RAINWATER HARVESTING mm and pebbles/boulders larger than 75mm pebbles There are different ways by which rain water is filled in three equal layers and connected to theharvesting is carried out. Some of the important well by 150 mm diameter PVC pipe and this pipemethods are discussed one by one as discussed in projects 0.5 to 1.0 m inside the well. The capacitycoming paragraphs. of the water tank may be taken about 50 m3. The percolation of water 400 to 1000 m3 per year is1. Utilizing Rainwater for Dewas Roof Water possible through this structure.Filter Dewas is the name of the city located in 4. Utilizing of Rainwater for Bore wellMadhya Pradesh. This roof water filter is first Rechargingpracticed at Dewas and hence the name Dewas roof Arrangement of bore well recharging is aswater filter. Fig.1 shows details of Dewar roof water shown in fig. 3. A six metre diameter collecting pitfilter. It can be made easily using sand pebbles of of 1.5 m depth is excavated around the bore welldifferent sizes. In this two caps are provided as T1 casing pipe. Another small pit of 1.5 m x 1.5 m xand T2. Keep the cap T1 and T2 always closed. The 0.6 m depth is made at the bottom of large pit andT2 is used for periodical back washing of filter and filled with filter media. A 75 mm diameter PVC pipecap T1 is used for backwash drainage. Small pebbles is connected to the bore well casing pipe after firstof size 6 mm are on entry side of rainwater. Use of layer of 75 mm pebbles. An inverted elbow ismedicine for water purification is made through cap connected to the pipe.T2. Do not recharge rainwater for first two days inrainy season. Keep the roof always clean, especially 5. Utilizing Roof Water to Recharge Trenchin rainy season so that quality of rain water falling The roof water collected can be rechargedon roof is not deteriorated. The cost of this roof through recharge trench. Water can be rechargedfilter excluding connecting pipe is about Rs 800. throughout the year either by using used water orFor average condition in Maharashtra, from 100 rainwater. This
  16. 16. recharge trench may get filled manysquare metres roof area about 50 m3 of water can times as per availability of used or rain water. Thisbe percolated through this filter. method is effective in the area where permeability 11 12. of soil is more. The capacity of the trench may be second sand filter surrounding the slotted section oftaken up to 20 m3. The percolation of water through the well at the top prevents the remaining suspendedthis pit of the order of 100 to 200 m3 per annum is material entering the well. Beyond this is a coirpossible. The cost of this structure may come about wrapping as a final protective filter before waterRs 5000. enters the well. The rate gradually decreases due to setting of slit at the top. Every year, after the rainy6. Utilizing Surface Rainwater to Recharge Tube season about one meter of the sand at the filter bedwell has to be replaced. Every year the well is developed Depleted aquifers are directly fed with surface with a compressor once immediately after therainwater by using a recharge tube well so that storage structures become empty because the waterrecharge is fast and evaporation and transit losses level is shallow immediately after the monsoon andare zero. development is effective. A typical recharge tube well is designed as During pumping when the water is clear, itfollows : may be allowed on the filtered bed so that it takes1. A borehole of 50 cm diameter is drilled to the down the slit accumulated in the filter bed into the desired depth. well which is being developed. Through this method2. A 20 cm diameter casing i.e. outer pipe of the the entire filter bed also gets cleared of the silt during bore well is designed by providing slotted the time of infiltration. perforated sections against aquifers.3. The depth of the recharge tube well should be 7. Utilizing Roof Water to Collect into the Storage about 30 metre below the water table in the area. Tanks4. The annular space between the borehole and Rainwater from the roof surface is drained the pipe is filled with good gravel and developed through gutters into storage tanks. To prevent with a compressor till it gives clear water. To contamination and dust to flow into the storage tanks stop the suspended solids from entering the there is a provision of a hand movable gutter recharge tube well, a filter mechanism is connection which can be manually moved to divert provided at the top. the water out. The rooftop is used as the collection5. A pit of dimensions 6 m x 6 m x 6 m is dug with device. Guttering generally made of PVC is used to the tube well at the center. transport the rainwater from the roof top to the6. This pit is filled with small rounded boulders, storage tanks. Storage tanks may be either above or stone chips and sand in layers with boulders at below the ground and should be properly covered. the bottom and sand at the top. In apartments more than one storage tanks can be7. The top one metre of the casing assembly in used and they can be interconnected through this pit is filled with sand. The top of the casing connecting pipes. The storage tanks should have pipe is provided with a cap which is about 600 provision of an adequate enclosure to minimize mm below the sand bed to prevent suspended contamination from human, animal or other material from entering the well. environmental contaminants. The end of the gutter,8. In order to release the air present in the casing which connects the storage tank, should be attached assembly during the percolation process of with a filter to prevent any contaminants to get into floodwater, the air vent is provided through a the storage tank. It is also advisable to drain the 75 mm diameter pipe connected to the first flow to get rid of the dust and contaminants recharging tube well within the top 600 mm from the roof top. through a reducer tee of dimensions 200 mm x 75 mm. The air releasing pipe is then extended CASE STUDY OF RAIN WATER to one of the banks where the vent is HARVESTING FOR BUILDING IN URBAN constructed. AND VILLAGE AREA Rain water harvesting system for annexure When flood water filters through the sand, building of Govt. College of Engineering,most of the suspended materials are filtered out. The Aurangabad is being considered for study purpose. 12 13. The Government Engineering College is located in III) Plumbing costMarathwada region of Maharashtra State. The a. PVC pipe 6" size total length 200 m @ Rsaverage annual rainfall of Aurangabad town is 100/- per m = Rs.20000/-around 700 mm/year. The population of the city is b. PVC pipe 4" size total length 120 m @Rs 85/-more than 10 lakh. Presently the water is supplied per m = Rs 10200/-to the town by Municipal Corporation, Aurangabad. c. Labour charges (Lump sum)Considering the capacity of water treatment plant, = Rs 20000/-the water is supplied to town on alternate day. d. PVC pipe accessories = Rs 10000/- The institute needs water about 350 m3 perday. In last few years it is observed that the ground IV) Tube Well 100 m deep and 2 H.P. pumpwater level of the town is being depleted. It is = Rs.30000/-essential to conserve the rainwater not only in the Total Expenditure = Rs142680 /-city itself but also in areas surrounding to The total cost of rain water harvesting systemAurangabad. No one can neglect the importance of project is Rs.142680/-rainwater harvesting. According it is proposed tocollect roof water from at least ten hoses from each Rain water harvesting system for villagevillage. It is also proposed to collect rainwater from communityroof of Annex building of this institute. If this roof This system is designed for the villagetop rain water harvesting scheme is implemented community situated in locality where there isall civil engineering students from this institute will scarcity of water. The annual rainfall is 650 mm perhave a role model. These students will see the system year. The water is supplied by panchayat/localand in future they will be motivated to implement authority alternate day. Incase of summer seasonroof water harvesting system elsewhere. The the water is supplied by tankers. So it is proposedtentative estimate is as given below. to conserve the rain water by allowing it to percolate so as to meet underground water. It is proposed toEstimate for rain water harvesting system for conserve rain water collected on top of every houseannex building and common rain water harvesting system isArea of building : 2159.78 m2 designed for group of 10 houses having approximatePerimeter of building : 335.45 m area of 70 m2 eachAverage annual rainfall at Aurangabad : 700 mmCoefficient of runoff : 0.8 Estimate for rain water harvesting system forQuantity of water to be harvested per year : village community 1209.47 m3 Area of group of houses : 700 m2Requirement of soak pit : 6 m x 6 m x 1.5 m (Two Perimeter: 340 mnumbers) Average annual rainfall: 650 mm Coefficient of runoff: 0.8I ) Cost of excavation : 2 x 54 m3 x Rs.60/- Quantity of water to be harvested per year: 364 m3 = Rs. 6480/- Requirement of soak pit: 3 m x 3 m x 2 mII) Cost of material for filling of soak pit I) Cost of excavation : 18 m3 x Rs.60/-a. 75 mm to 100 mm size aggregate = Rs. 1080/- = Rs. 12000/-b. 15 mm to 25 mm size aggregate II) Cost of material for filling of soak pit = Rs. 12000/- a. 75 mm to
  17. 17. 100 mm size aggregatec. Sand = Rs. 8000/- = Rs. 2500/-d. Protection wall with perforation b. 15 mm to 25 mm size aggregate = Rs 8000/- = Rs. 2500/-e. Labour cost for filling material ( Lump sum) c. Sand = Rs. 2000/- = Rs. 6000/- 13 14. d. Protection wall with perforations failing on his roof, plot, and farm and recharges it = Rs 2000/- under ground. Two cases of roof top watere. Labour cost for filling material harvesting for urban and rural area have been = Rs. 5000/considered in the present study. Similarly for other building roof top rain water harvesting can beIII) Plumbing cost implemented. In fact there is no village anda. PVC pipe 4" size total length 200 m @Rs 85/- habitation in India that cannot meet its basic drinking per m = Rs.17000/- and cooking needs through rainwater harvestingb. Labour charges (Lump sum) techniques. = Rs 8000/-c. PVC pipe accessories = Rs 6000/- REFERENCES Expenditure for one unit of ten houses 1. Gawai A.A. and Aswar D.S. (2006) ―Towards = Rs 46080/- Self reliance for Water Needs through Rain Water Harvesting‖ Conference on ‗EngineeringCONCLUSION Technology for Efficient Rain Water Harvesting Water is essential element of life. Everyone and Soil Conservation‘, S.G.G.Nanded, 29-30knows that, if we do not harness available sources May 2006.pp. 1-7of water and use them judiciously with proper care 2. Kaushal Kishore (2004) ―Rain Waterthe problem of water scarcity is going to be serious. Harvesting‖, Journal of Civil Engineering andIrrespective of fast development in all fields of Construction Review, May 2004, pp.42-48science there can be no substitute to water. Hence, Magar R.B. and Waghmare S.T. . (2006) ―Rainit is necessary to opt for various water harvesting Water Harvesting‖ Conference on ‗Engineeringmeasures. It is the responsibility of government Technology for Efficient Rain Water Harvestingorganization as well as individual to harvest each and Soil Conservation‘, S.G.G.Nanded, 29-30drop of water falling on earth surface. For this, it is May 2006.pp. 44-51necessary that each person collect the raindrops 14 15. 15 16. National Seminar on Rainwater Harvesting and Water Management 11-12 Nov. 2006, Nagpur 4. Harvested Rainwater for Drinking *Dr. N. Balasubramanya Abstract It is clear from the World water quantity that out of total available water, only 0.3% is available for human consumption. But today even this is getting polluted due to human activities like mining, industrialization has created acute shortage of potable drinking water. Rain water harvesting is one of the most ancient and easy methods that can be adopted at urban and rural level efficiently. The aim of this study is to investigate the possibility of using harvested rainwater as a source of drinking water without causing any health risk. This can be achieved by adopting suitable storage technique efficient and economical treatment methods. Roof harvested rainwater samples were collected from five different places of Bangalore during October 2005. The water samples were collected and stored in good grade plastic containers and were subjected to periodical treatments (like chlorination, solar disinfections and use of silver nitrate) and tests fro and use of silver nitrate and tests for physical chemical and Biological parameters up to May 2006 as per IS 10500:1991. All the above treatment methods suggested proved to be highly effective in reducing the colonies fro an initial value of around 300 to zero.Introduction increases due to increase in the population. Hence, For centuries world has relied upon rainwater the most effective way to obtain fresh drinking waterharvesting to supply water. Rainwater harvesting is to harvest rainwater. Rainwater harvesting systempromotes self sufficiency and fosters an appreciation is inherently simple in form, and can often befor water as a resource. It saves money, saves other assembled with readily available materials byresources of water, reduces erosion and storm water owners, builders with a basic understanding of therunoff and increases water quality. plumbing and construction skills. Rainwater can provide clean, safe and reliable The present investigations was proposed withwater for drinking so long as the collection system a vision to overcome the scarcity of drinking wateris properly constructed and maintained and treated during the non – rainy seasons such that it givesappropriately for its intended use. easy and economical solution that can be adopted Rainwater harvesting means capturing rain both in urban and rural areas.where it falls or capturing the runoff in a village ortown and taking all precautions to keep it unpolluted. Sample Collection and Storage One third of world‘s population will Rainwater samples were collected from fiveexperience severe water scarcity by the end of this different places of Bangalore during October 2005.century. In rural areas, the water may not be fit for The samples were stored in good grade plastic cans.drinking due to the polluted water bodies, due to The above samples were tested for physical,contaminated ground water and also due to acute chemical and microbiological parameters. Table 1water scarcity. In urban areas, water demand gives the experimental finding. * Professor, Dept. of Civil Engineering, M.S.Ramaiah Institute of Technology, Bangalore – 54 16 17. Table 1 : Experimental Results of Physical, Chemical & Biological Parameters Sample Date of Expt Turbidity pH Do Hardness Chloride Alkalinity Acidity NTU mg/l of mg/l mg/l mg/l of mg/l of CaCO3 CaCO3 1. Banashankari 14/08/05 4.6 7 7.8 56 13.96 86 06 2. MSRIT 17/01/06 6.3 8.4 7.7 22 16 30 08 3. Shivajinagar 21/11/05 8.3 8.11 8 58 13.2 40 06 4. Vijayanagar 18/01/06 11.9 7 7.7 58 21.3 46 12 5. Vidyaranyapura 12/12/05 7.3 8 8.1 46 12 18 14 A detailed study of Table 1 reveals that both sis hours. Such an exposure increases thethe physical& chemical parameters are very much temperature of water and also gives an extendedwithin the limits for drinking water standards dose of solar radiation killing the microbes.specified by WHO (1984) and IS 10500:1991.However, the colony counts were quite significant Chlorinationin all the five samples. Chlorination is one of the most reliable Therefore, it was decided to emphasize more methods of disinfecting drinking water. In thison the microbiological contaminations and suitable method the calculated amount of chlorine is addedtreatment methods to make the rainwater fit for to one litre of water sample for a specified tune anddrinking. thereafter tested for the coliform counts.Treatment methods and Results Silver Nitrate All the five rain water samples were subjected Silver nitrate is very small doses of 0.05 toto the following treatments. 0.1 mg/l helps in disinfecting the drinking water.• Solar disinfection Silver nitrate in smaller doses does not impart any• Chlorination taste, odour or produces any harmful effect on• Using Silver nitrate human body.• Combination of the above method. Combination of the above methodsSolar Disinfection In order to investigate the effectiveness of the Solar disinfection is a process where in treatment methods following combinations weremicrobes are destroyed through temperature and tried.ultra violet radiation provided by
  18. 18. the fun. a) Chlorine + Solar disinfection Water is filled either in a clean transparent or b) Silver nitrate + Solar disinfection.painted (Black) bottle oxygenated by shaking,followed by topping up. It is placed in the horizontal Tables 2,3 & 4 presents the details of coliformportion on tope exposed to direct sunlight for about counts of the above specified treatments. Table 2: Coliform Count (At room temperature) Sample Date of Collection Date of experiment Coliform Count/100ml (Average of 3 tests) Chlorination Silver Nitrate 1. Banashankari 20/10/05 17/05/06 0 0 2. MSRIT 25/10/05 17/05/06 0 0 3. Shivajinagar 25/10/05 17/05/06 0 0 4. Vijayanagar 25/10/05 17/05/06 0 0 5. Vidyaranyapura 28/10/05 17/05/06 0 0 17 18. Table 3 : Coliform Count (Solar disinfection using transparent bottle) Sample Date of Date of Expt Coliform count / 100ml Collection Transparent Bottle Chlorination Silver nitrate (Average of 3 tests) 1. Banashankari 20/10/05 17/03/06 40 0 0 2. MSRIT 25/10/05 24/03/06 38 0 0 3. Shivajinagar 25/10/05 02/04/06 40 0 0 4. Vijayanagar 25/10/05 15/04/06 35 0 0 5. Vidyaranyapura 25/10/05 21/04/06 28 0 0 Table 4 : Coliform Count (Solar Disinfection using black painted bottle) Sample Date of Date of Expt. Coliform Count / 100 ml (Average of 3 tests) Collection Black Bottle Chlorination 1. Banashankari 20/10/05 17/03/06 2 0 2. MSRIT 25/10/05 24/03/06 2 0 3. Shivajinagar 25/10/05 02/04/06 3 0 4. Vijayanagar 25/10/05 15/04/06 2 0 5. Vidyaranyapura 28/10/05 21/04/06 0 0 Careful study of Table 2 depicts that Conclusionschlorination and Silver nitrate in very small dosages Rainwater collection is easy and economicalare very effective even at room conditions, justifying both in rural and urban areas.their selection. Rainwater harvested during Oct 2005, tested till Detailed study of Table 3 indicates that solar May 2006 without much changes in physicaldisinfection using a transparent bottle is not very properties like colour, odour & turbidity, inspiteeffective in reducing the coliform counts. However, of the fact that they were from various sourcesaddition of chlorine and silver nitrate have proved and stored in normal food grade plasticto be highly effective, further strengthening their containers.selection as disinfectants. All the treatment methods suggested are highly Finally from Table 4, it can be seen that solar effective in reducing the microbiologicaldisinfection using a black painted bottle has yielded contamination and also viable both at rural andin a more effective disinfection, the coliform counts urban levels.have very significant, reduced. The reason being Rainwater harvesting and its treatment isthat a black bottle or body absorbs more heat, which affordable by individuals and will be highlyenables in destroying the bacteria. In the present useful in drought prone areas.investigations is was observed that the watertemperature in the bottles recorded a temperature Futurearound 500 C. It is suggested that similar investigations are It is also very interesting of disinfection to made on a number of samples collected fromnote that the chlorination method has established different places, stored under different conditions.its supremacy. 18 19. Acknowledgement Proe. 23rd WEDC Conf. Sep 1-5 1997, Durban The author wishes to thank the management S.Africa.of M.S.Ramaiah Institute of Technology, Bangalore 6. Sharma S.K. and Jain S.K, Proceedings of the560054 for all the encouragements & inspiration International Conference on Management ofprovided for the study. Also many thanks are due to Drinking water resources – central leatherMr.Sunil Hegde, Mr.Anantha Padmanabha & Research Institute. Anna University & TamilMr.Vinay Final Year B.E. Students for their help Nadu Water supply & Drainage, Board,during the course of the experimental investigations. Chennai, 1997, pp129-138. 7. Wegelin M & Sommer B, Solar waterReferences : disinfections (SODIS) – Destines for world1. Bell, F.A.Jr, D.L.Jerry, J.K.Smoth, and wide use. Water lines, Vol 16, No.3, IT S.C.Lynch, Studies on home water treatment Publications, London 1998. systems. Jr.Am water works Assoc. 75:104-107- 8. Winter bottom, Daniel ―Rainwater Harvesting, 1984. An ancient technology – cisterns in2. Davies C.M., and Evison L M ―Sunlight & the reconsidered, Landscape Architecture‖, April survival of entropic bacteria in natural water .2000 pp 42-46. Journal of applied Bacteriology 7, 265-274- 9. White G.C, Hand Book of chlorination & 1991. Alternative Disinfectants, Johns Wiley & Sons,3. Drinking water standards, www.epa.gov/safe Inc, New York 1999. water/md.html. 10. Wolfe R.L., 1990, ―Ultraviolet Disinfection of4. I.S. 10500:1991 ―Drinking Water Standards‖. Possible water‖ Env.Sci and Technology 24(6),5. Jalbottt R ―Rural water supply and Sanitation 768-773, 1990. program in India – Goals, roles & innovation. 19 20. National Seminar on Rainwater Harvesting and Water Management 11-12 Nov. 2006, Nagpur 5. Rain Water Harvesting and Ground Water Recharge *Madhaorao Bajirao Deshmukh1.1 Water is an essential natural resource for By adopting water harvesting, an additional 160sustaining life and environment. The available water BCM shall be available for use.resources are under pressure due to increasingdemands and the time is not far when water, which 3.2 Ground water level in some areas are falling atwe have always thought to be available in abundance the rate of one meter per year and rising in someand free gift of nature, will become a scarce other areas at the same rate.commodity. Conservation and preservation of water You can capture and recharge 650000 liters ofresources is urgently required to be done. Water rainwater from a 100-sq. meters size rooftop andmanagement has always been practiced in our meet drinking and domestic water requirement ofcommunities since ancient times, but today this has family of four for 160 days.to be done on priority basis. The number of wells and borewells for irrigation in the country has increased five fold to1.2 India‘s population has recently crossed the one 175 lacks during past fifty years.billion mark, with an ever-increasing population, our There are 25 to 30 lack wells and borewells forcountry faces a serious threat to the management of drinking, domestic and industrial uses.her water resources as the gap between demand and More than 80% of rural and 50% of urban, industrialsupply widens. and irrigation water requirement in the country are met from ground water.2.1 In our villages and cities, down the ages, peoplehave developed a wide array of techniques to harvest 3.3 Causes Of Fall In Ground Water Levelsrainwater, which are simple, efficient and cost • Over exploitation or excessive pumpage eithereffective. There is a tendency to ignore these locally or over large areas to meet increasing watertraditional water-harvesting systems. We should demands.draw upon the wisdom of our ancient life sustaining • Non-availability of other sources of water.systems and through better management, conserve Therefore, sole dependence is on ground water.our precious water resources. • Unreliability of municipal water supplies both in terms of quantity and timings, driving people to2.2 Harvesting of rainwater is of utmost important there own sources.and the ministry of water resources is embarking on • Disuse of ancient means of water conservationsuch programme. A judicious mix of
  19. 19. ancient like village ponds, baolis, percolation tanks andknowledge, modern technology, public and private therefore, higher pressure on ground waterinvestment and above all, people‘s participation will development.go a long way in reviving and strengthening waterharvesting practices through out the country. 3.4 Effects Of Over Exploitation Of Ground Water Resources3.1 Ground Water Resources: - Annually • Drastic fall in water levels in some areareplenishable resources are assessed as 432 billion • Drying up wells/ borewellscubic meters (BCM) • Enhanced use of energy *B.Sc., B.E. (Hon), AMICE (USA), Ex- Superintending Engineer, 54, Tatya Tope Nagar, Nagpur 20 21. • Deterioration in ground water quality • Benefiting in the water quality• Ingress of sea water in coastal areas. • Arresting sea water ingress • Assuring sustainability of the ground water4.0 Method And Techniques Of Rain Water abstraction sources and consequently the village andHarvesting town water supply system• Roof – top rain water harvesting and its • Mitigating the effect of droughts and achievingrecharge to underground through existing wells and drought proofingborewells or by constructing new wells, borewells, • Reviving the dying traditional water harvestingshafts etc. structures and their rehabilitation as recharge• Capturing and recharging city storm water run structures.off through wells, shafts, storm water drains. • Effective use of lack of defunct wells and• Harnessing run off in the catchment by tubwells as recharge structureconstructing structures such as gabions, check dams, • Up gradation of social and environmental statusbhandaras, percolation trenches, sub-surface dykes etc.etc.• Recharging treated and industrial affluent 7.0 Proposed Policy Measures For Rain Waterunderground by using it for direct irrigation or Harvestingthrough ponds, basins or wells etc. • Provides at least one roof-top rain water harvesting structure for every 200sq. meters plot in5.0 Objective Of Rain Water Harvesting urban areas.• Restore supplies from the aquifers depleted due • Revive/ rehabilitation all village pondsto over exploitation • Subject to technical feasibility, provides at least• Improve supplies from aquifers lacking one check dam / KT weir / Sub- surface dyke inadequate recharge. each streamlet with catchments of 1 to 3 sq. km.• Store excess water for use at subsequent times. • Provide all drinking water wells with a recharge• Improve physical and chemical quality of structureground water • Ban construction of irrigation wells / tubewells• Reduced storm water run off and soil erosion within a distance of 200 m or less (depending on• Prevent salinity ingress in coastal areas. scientific criteria) of the drinking water supply well.• Increase hydrostatic pressure to prevent/ stopland subsidence. 8.0 Success Stories Of MAHARASHTRA• Recycle urban and industrial wastewater etc. • In Yaval taluka, Jalgaon District, Six• Rehabilitate the existing traditional water percolation tanks, two recharge shafts and oneharvesting structure like village ponds, percolation injection well were constructed- A total of about 546tanks, baolis, tanks, etc ha area benefited• With minor scientific modifications and • In Amravati District, three percolation tanksredesigning, convert the traditional water harvesting and ten cement plugs benefiting an area of 280 hastructure into ground water recharge facilities. and 100 ha respectively have been constructedrise• Use the existing defunct wells and borewells in water level up to 10 meters recorded.after cleaning and also the operational wells as • Experiments of catchments treatment carriedrecharge structures. out at Adgaon and Palaswadi in Aurangabad, Ralegaon Siddhi in Ahmednagar and Naigaon in6.0 Benefits Of Rain Water Harvesting Pune by Shri Anna Hazare - effort have led to revival• Rise in ground water levels in water of streamlets and enhanced availability of ground• Increased availability of water from wells water in the water shed.• Prevent decline in water levels• Reduction in the use of energy for pumping 9.0 Proposed Strategywater and consequently the costs. • Organize Mass Awareness Programmes• Reduction in flood hazard and soil erosion involving district administration and NGOs to 21 22. educate in different sections of users and to make industrial houses to be invited to participate in thethe programme demand oriented. work and adopt towns and villages and provide• Roof-Top rain water harvesting and its recharge financial support.underground through more than two lack existing • Government organizations to act as facilitatorsbut defunct drinking water and irrigation wells, or and provide technical and financial support forby constructing new wells, borewells, Shafts, creating the demonstration facilities etc.spreading basins etc.• Make roof-top rain water harvesting and 10.0 Future Action Plansrecharge mandatory in all urban dwellings. • Prepare national and state level water• Capturing city storm water run- off and harvesting perspective plans.recharging it through wells, shafts, spreading basins, • Develop plans and implement roof-top rainstorms and water drains etc. water harvesting measures using 1,00,000 wells• Harnessing run off in catchments by (existing, defunct and or operative wells to be usedconstructing structures such as gabions, check dams, in the first instance)bhandaras, percolation trenches, bus-surface dykes • Provide rural drinking water wells withetc. recharge facilities- cover 1,00,000 wells• Impounding surface run from village • Harvest and recharge city storm water in 100catchments and water shed(s) in village ponds and townspercolation tanks. • Revive and rehabilitate 1, 000 dying village• Rehabilitation all ancient rain water harvesting ponds.structures. • Design and construct 200 percolation tanks,• Invoke legal provision, if and when required, 5000 check dams/ bhandaras and 1,000 sub surfaceto regulate indiscriminate boring of wells and to dykes.make the installation of recharge facilities mandatory • Recycle secondary treated urban waste water• Constitute water user Association (WUA) or through aquifers at five centers.village Beneficiary Groups (VBG) NGOs to • Identify potential aquifers in drought proneorganize the constitution of these bodies. The WUA/ areas and declare these apart as ―Ground WaterVBG and NGOs to be associated with the project Sanctuaries‖right from the concept to completion stages.• For expanding further scope of work, the Ref: - CENTRAL GROUND WATER BOARD- MINISTRY OF WATER RESOURCES. 22 23. National Seminar on Rainwater Harvesting and Water Management 11-12 Nov. 2006, Nagpur 6. Rain Water Harvesting Tanks for Supplementing Minor Irrigation Tanks during Drought * Mohd. Mahboob HussainIntroduction : development etc. Rainwater harvesting is usually India‘s total land area is 3287263 Sqkm. The classified into two types (i) harvesting forcultivated land is 55.7% i.e., 183.09 million hectors. agriculture (irrigation) needs and (ii) harvesting forAverage annual rainfall is 117 Cm; average monsoon domestic and other needs. For irrigation needs therainfall is 55 Cm. The occupation of about 70% of rainwater can be harvested during rainy season bypeople in India is agriculture. The population of constructing
  20. 20. any of the following structures.India is fed on the food production of the country. 1. Major storage reservoirMain source of water in this country is rainfall 2. Medium storage reservoirduring monsoon season. The rainfall mainly 3. Minor storage tanksconfined in the months from June to September. But 4. Watershed development Structures, likeit is not regular and erratic with respect to both time Check dams, percolation tanks, Sunken gully pitsand place. Now a days drought and floods are the etc.,sever hazards in different parts of our country. The Looking in to the rainfall trends in past fortyrequirement of agricultural produce is expected to years it is felt that rain water above 75% P.L. shouldrise steeply by 2025.Hence India must concentrate be stored for beneficial use during droughts / lowon increasing area under irrigation and improving rainfall year. In this paper it is proposed to constructthe productivity of both land and water to meet the Rain Water Harvesting Tanks for the beneficial useneeds of the population. The demand of water of water for supplementing minor irrigation tanksincreasing due to several factors such as increase in during drought years. Rain Water Harvesting ispopulation growth, which has led to a situation in being promoted extensively in India, particularlywhich water has become a scarce resource. Hence in the Southern States.it is very essential to harvest rainwater during rainyseason. Rainwater harvesting is the intentional Need for Rain Water Harvesting Tanks :collection of rain water from a surface and its Since rivers occasionally swells, hence somesubsequent storage in order to supply water during countries have built oversized capacity reservoirsthe time of demand. Rain water harvesting is to store surplus water which will other wise beessential in view of the fact that rainfall, which is a wasted in to sea. For example, Egypt had builtsource of fresh water, occurs in very short spells Oswan Dam to store water about five times the yieldand runs off as a waste unless arrangements are available in Nile River. During droughts they aremade for its storing. successfully irrigating lands so that the country is Main source of irrigation development are not vulnerable by famine. In most of the areas ofdams and canals. Other option are water harvesting semiarid region yearly rainfall is below the normalstructure such as for ground water development, for continuous two to three years followed by asurface minor irrigation systems, watershed normal rainfall year. The year wise monsoon rainfall * Deputy Executive Engineer, Medium Irrigation, I & C.A.D.Department, Govt. of A.P., Hyderabad 23 24. for some of the rain-gauge stations of Ranga Reddy natural resource. Hence all water over and aboveDistrict in Andhra Pradesh are shown in annexure- 75% dependable yield is wasted in to sea. SinceI and graph enclosed showing rainfall variation for rainfall is a natural phenomenon, we do not knowlast 40 years indicates that lot of water above 75% when and in which year rainfall will be above 75%P.L .is wasted. More over from rainfall graphs it P.L., hence it is the need of the hour to harvest Raincan be seen that there are number of years when water above 75% P.L. also and to utilize during thethere is rainfall more than 75 % P.L followed by a drought / low rainfall year. It is proposed to constructlow rainfall year. From graph of Monsoon rainfall Rain Water Harvesting Tanks without any canalversus year for Medchal R.G.S, the following system with a sluice to letdown water in the downconclusions are drawn. stream for existing minor irrigation tanks. For one R.G.S (i.e., TANDUR) the year wise(i) In the year 1967 there is excess rainfall over total yield available for one of the subgroup having 75% P.L. followed by a normal rainfall year 20 Sq.Miles for 40 years have been calculated. The 1968 and a low rainfall year in 1969. yield available @ 75 % PL also has been calculated(ii) In the year 1971 the rainfall is much higher using strange‘s table which works out to 255.64 than 75% P.L. followed by low rainfall year Mcft. The surplus yield available after deducting of 1972. the yield @ 75 % PL from the total yield is also(iii) In the year 1974 the rainfall is much higher calculated year wise. Statement showing the above than 75% P.L. followed by low rainfall year values year wise are presented in annexure- II of 1975. enclosed. From the statement it is observed that for(iv) In the year 1976 the rainfall is much higher 30 years there is surplus yield available. The than 75% P.L. followed by low rainfall year maximum surplus yield is 801.20 MCft. The of 1977. average of surplus yield for 30 years is 267.495(v) In the year 1978 the rainfall is much higher Mcft, but where as the 75% dependable yield is than 75% P.L. followed by low rainfall year 255.64 Mcft. The average of surplus yield is slightly of 1979. higher than the yield available at 75% dependability.(vi) In the year 1983 there is flood followed by a Since every year the surplus yield may not be normal rainfall year of 1984 and a low rainfall available so much, hence it is proposed to utilize at year of 1985. least 50% of the yield available at 75%(vii) In the year 1990 the rainfall is much higher dependability duly constructing Rain Water than 75% P.L. followed by low rainfall year Harvesting Tanks. In the statement minus values of 1991. indicates that the yield available is below the 75%(viii) In the year 1996 the rainfall is much higher PL yield for ten years out of 40 years. Hence there than 75% P.L. followed by low rainfall year is scope for storing this surplus yield in the proposed of 1997. Rain Water Harvesting Tanks.(ix) In the year 2000 the rainfall is much higher More over sometimes heavy rainfall occurs than 75% P.L. followed by low rainfall year in one single month followed by a dry spell of 20 to of 2001. 30 days. In such case also this excess water due to heavy rainfall can be stored in Rain Water From the above it can be stated that the water Harvesting Tanks and released for existing minorabove 75% P.L. can be stored in the proposed Rain irrigation tanks during dry spell so that crops canWater Harvesting Tanks and used in the low rainfall be grown successfully.years. Presently any irrigation project is design to The World Banks has published a reportutilize water out of the available 75% dependable ―India‘s Water Economy: Bracing for a turbulentyield. Water has to be harvested, preserved and future‖. In this report it is highlighted that India‘sutilized for beneficial used, as it is becoming a scarce storage capacity of 200m3 per person is too little, as 24 25. compared to over 5000 m3 per person in U.S.A. through natural stream with minimum conveyanceand Australia, and 1000 m3 per person in Mexico losses. The Rain Water Harvesting Tanks shouldand China. It is also highlighted that the need for essentially have a sluice and a surplus weir tostorages in India will be even more in the post dispose off flood water. The sluice can be used toclimate change scenario. In India the poverty in let down water to the down stream existing minorirrigated districts is one third of that in unirrigated irrigation tanks. The design procedure of minordistricts. Hence the proposed Rain Water Harvesting irrigation tank can be adopted for design of RainTanks will increase storage capacity per person in Water Harvesting Tanks. The capacity of each RainIndia. Water Harvesting Tank can be fixed based on the number
  21. 21. of tanks to be taken up as Rain WaterMethodology for Proposing Rain Water Harvesting Tanks duly utilizing at least 50 % of theHarvesting Tanks : utilization of that of minor irrigation tank designed In a sub-group of a given sub-basin of a river for 75 % dependable water. Eg: - In a given sub-basin there may be few minor irrigation tanks, check group if the 75% dependable water is 100 M.cft.dams and percolation tanks which together may and the existing utilization is 80 M.cft. underutilize 75 % dependable yield. Whenever there is existing minor irrigation tanks. Rain Waterhigh rainfall above 75% P.L. in the catchment, the Harvesting Tanks should be design to hold 40 M.cft.water go waste down stream and ultimately joins of water, which is 50% of present utilization. Tosea. We may not be able to know how much surplus store 40 M.cft. of water, now propose 4 tanks ofwater (above 75% P.L.) a sub-group catchment each 10 M.cft. live capacity in the upper reaches ofyields. Hence it is proposed to utilize at least 50 % streams so that this water can be utilized duringof the water utilization of that of existing tanks droughts / low rainfall year.designed to utilize 75 % dependable water, so thatif there is failure of monsoon next year we can make Plan of operation for Rain Water Harvestinguse of this water for irrigation and avoid drought. Tanks :The following sketch shows probable locations of Once these Rain Water Harvesting Tanks areRain Water Harvesting Tanks in a given sub-group. constructed, the sluices should be kept open so thatThe Rain Water Harvesting Tanks should be located when it rains the water will flow down to the existingin the initial reaches of streams, so that the stored minor irrigation tanks to fill them up to their fullwater can be utilized for filling the minor irrigation tank level in the monsoon. When the minor irrigationtanks when there is scanty rainfall and hence crops tanks are filled up the sluices of Rain Watercan be grown successfully. Harvesting Tanks should be closed so that water can be stored in these Rain Water Harvesting Tanks. Then depending up on the number of fillings required ( as per design ) again water can be released to lower existing minor irrigation tanks for their full utilization as per hydrological clearance given . Now close the sluices of Rain Water Harvesting Tanks and store water up to full tank level. If there are heavy rains again the surplus water will automatically flow down through surplus weir. Next year when monsoon are late, some quantity of water from these Rain Water Harvesting Tank can beDesign of Rain Water Harvesting Tanks : released through sluices to the existing minor Select the site of Rain Water Harvesting Tanks irrigation tanks so that farmers can take up landsuch that it can feed the minor irrigation tank preparation and sowing can be done in time. Even 25 26. if the monsoon fails the remaining water also can be (9) There will be soil conservation in the upperreleased to down stream tanks so that the crops can reaches of the catchment because ofbe grown successfully. In a year when total rainfall construction of Rain Water Harvesting Tanks.is less than normal, these Rain Water Harvesting (10) There is a need to workout surplus yields forTanks can be kept empty. every year for each Rain Gage Stations and prepare model for storing water in Rain WaterConclusions : Harvesting Tanks to utilize surplus water(1) The concept of Rain Water Harvesting Tank optimally. is to store water during excess rainfall year (11) As water is becoming scarce natural resource, (above 75% P.L.) and to utilize during drought the cost of construction of Rain Water /scanty rain fall year. Harvesting tanks should not come into way.(2) Since Rain Water Harvesting Tanks are (12) There is a need to formulate a coherent policy designed to store surplus water over and or strategy towards strengthening extension above 75% P.L yield, there will not be any and technical support for Rain Water effect on existing minor irrigation system. Harvesting Tanks for crop production.(3) Success rate of existing minor irrigation tanks can be ensured by regulation of water from References : Rain Water Harvesting Tanks, thus utilizing (1) ―Innovative participatory technologies for water optimally. water shed development in drought prone(4) Generally minor irrigation tanks are designed areas of India‖ by Sri. T. Hanmanth Rao, for 150% irrigation intensity. Because of Consultant of united nation. proposed Rain Water Harvesting Tanks in (2) ―Hand book for planning water shed upstream by storing surplus water, the management works‖, Government of India, intensity of irrigation can be increased to Ministry of water resources, CWC, 200% by supplying water for Rabi crops by December, 2000. virtue of which food production can be (3) Paper on ―Irrigation development in India‖ enhanced. by Sri. Uddhao Wankede published in(5) These Rain Water Harvesting Tank can serve proceedings of National Seminar on ― as percolation tank in upper reaches of Irrigation development India‖ held from 9- catchments to improve ground water table, 10 October 2004 hosted by the Institution of as there will be some dead storage below sill Engineers (India), Nagpur local Center. level of sluice of that tank. (4) Irrigation manual by Illys.(6) Because of construction of Rain Water (5) ―Rain water harvesting – a case study in a Harvesting Tanks the loss due to flood collage campus in Mysore‖, by Sri. M. R. damages can be minimized. YADUPATHI PUTTY & Sri. P.RAJE URS,(7) Wastage of heavy surplus water in to sea can Dept. of civil engineering, National Institute be minimized. of Engineering, Mysore published in(8) Rain Water Harvesting Tanks also will be very Hydrology Journal of Indian Association of much useful for flora and fauna for Hydrologist volume 28, November 3-4, maintaining ecology of that area. September – December 2005. 26 27. ANNEXURE - IMonsoon Rainfall ( in mm ) of different Rain guage stations of R.R. District in A.P S.No Year Medchal Tandur Himayat Sagar 1 1960 N/A N/A 551.2 2 1961 N/A 909.1 571.2 3 1962 N/A 1063.6 856 4 1963 759.9 942.8 751.8 5 1964 710.3 751.5 710.8 6 1965 671.9 663.6 796 7 1966 468.2 493.1 689.4 8 1967 804.2 670.2 865.4 9 1968 663.4 652.3 440.9 10 1969 600.9 684.4 452.4 11 1970 754.9 992.9 842 12 1971 797.7 459.3 497.6 13 1972 547.8 454 221.7 14 1973 957.6 1097 633.5 15 1974 784.4 850 614.4 16 1975 566.7 1116.5 1689.6 17 1976 720.1 725.1 906.8 18 1977 584.1 480.8 568.5 19 1978 783.3 1216.6 1009.7 20 1979 440.3 585.2 564.6 21 1980 845.2 650.5 577.6 22 1981 1102.8 711.9 660.1 23 1982 862.8 665.9 564.6 24 1983 1858.5 1036.6 793.2 25 1984 673.7 651.6 595.6 26 1985 563.1 822.6 550.9 27 1986 445.9 645 586 28 1987 604.8 853.8 795.5 29 1988 933.4 961.1 741.4 30 1989 845.3 864.4 711.5 31 1990 760.4 1173 721.6 32 1991 624.8 767.4 393.4 33 1992 645.8 795.8 611.9 34 1993 767.5 697.2 479.8 35 1994 787.2 479.8 598.7 36 1995 899.9 790.8 1077 37 1996 775.8 758.6 803.7 38 1997 533.6 648.3 514.4 39 1998 988.6 1342.1 983.5 40 1999 701.3 670.7 540.8 41 2000 791.3 861.9 N/A 42 2001 589.6 N/A N/A N/A – 43 2002 629.4 N/A N/A Not Available. 27
  22. 22. 28. Annexure- II Statement showing the surplus yield beyond 75% dependabilityNo. Year Monsoon Yield per Total Yeild Yeild Surplus % of Surplus Rainfall Sq.miles from Available Yeild Yeild beyond in mm in MCft subgroup @ 75% PL 75 % PL C.A ( 20 Sqm)1 1961 909.1 27.25 545 255.64 289.36 113.192 1962 1063.6 38.566 771.32 255.64 515.68 201.723 1963 942.8 29.53 590.6 255.64 334.96 131.034 1964 751.5 17.742 354.84 255.64 99.2 38.85 1965 663.6 13.317 266.34 255.64 10.7 4.196 1966 493.1 6.479 129.58 255.64 -126.06 -49.317 1967 670.2 13.628 272.56 255.64 16.92 6.628 1968 652.3 12.783 255.66 255.64 0.02 0.019 1969 684.4 14.297 285.94 255.64 30.3 11.8510 1970 992.9 33.148 662.96 255.64 407.32 159.3311 1971 459.3 5.417 108.34 255.64 -147.3 -57.6212 1972 454 5.255 105.1 255.64 -150.54 -58.8913 1973 1097 41.248 824.96 255.64 569.32 222.714 1974 850 23.447 468.94 255.64 213.3 83.4415 1975 1116.5 42.841 856.82 255.64 601.18 235.1716 1976 725.1 16.322 326.44 255.64 70.8 27.717 1977 480.8 6.079 121.58 255.64 -134.06 -52.4418 1978 1216.6 51.618 1032.36 255.64 776.72 303.8319 1979 585.2 9.872 197.44 255.64 -58.2 -22.7720 1980 650.5 12.698 253.96 255.64 1.68 -0.6621 1981 711.9 15.647 312.94 255.64 57.3 22.4122 1982 665.9 13.426 268.52 255.64 12.88 5.0423 1983 1036.6 36.404 728.08 255.64 472.44 184.8124 1984 651.6 12.75 255 255.64 -0.64 -0.2525 1985 822.6 21.767 435.34 255.64 179.7 70.2926 1986 645 12.437 248.74 255.64 -6.9 -2.727 1987 853.8 23.691 473.82 255.64 218.18 85.3528 1988 961.1 30.863 617.26 255.64 361.62 141.4629 1989 864.4 24.37 487.4 255.64 231.76 90.6630 1990 1173 47.745 954.9 255.64 699.26 273.5331 1991 767.4 18.627 372.54 255.64 116.9 45.7332 1992 795.8 20.213 404.26 255.64 148.62 58.1433 1993 697.2 27.448 548.96 255.64 293.32 114.7434 1994 479.8 6.048 120.96 255.64 -134.68 -52.6835 1995 790.8 19.926 398.52 255.64 142.88 55.8936 1996 758.6 18.139 362.78 255.64 107.14 41.9137 1997 648.3 12.593 251.86 255.64 -3.78 -1.4838 1998 1342.1 52.838 1056.76 255.64 801.12 313.3839 1999 670.7 13.652 273.04 255.64 17.4 6.8140 2000 861.9 24.21 484.2 255.64 228.56 89.41 28 29. 29 30. 30 31. National Seminar on Rainwater Harvesting and Water Management 11-12 Nov. 2006, Nagpur 7. Rain Water Harvesting and Recharging Ground Water *R. K. Parghane *S. P. Kulkarni **A.W. DhawaleINTRODUCTION : WATER AVAILABILITY : Water is the most important resource of the India receives precipitation (includingentire society as a whole, since no life is possible snowfall & rain) of around 4,000 billion cubicwithout water. As water, being a limited resource, metres (BCM), only 1,869 BCM is accessible water,its efficient use is basic to the survival of the ever of which India uses barely a third. Nearly 1,179increasing population of the world. In India, the BCM of water drains in to the sea. Region, whoseground water is mainly used for drinking and yearly renewable freshwater availability is belowagricultural purposes. About 85% of drinking water 1,700 m3/ person is called as the water stress region.is available through dug well, bore well, filter point And the region whose yearly availability falls belowand tube well etc. The per-capital availability of 1,000 m3 / person is termed as water scarcity region.water at national level has reduced from about 5,177 But national figure of annual average per capitam3 in the year 1951 to present level of 1,869 m3. water availability is 2,464m3. It shows that theIn view of this, water management is very critical country is not in the water stress range so far.for the growth and development of any economy, However in some regions per capita availability ismore so in a large country like India which is as low as 411m3. (Kanyakumari, Pennar, Kutchh,endowed with many large rivers, lakes and wells Kathiawar, Krishna basin, etc. )that need to be conserved, better managed, recharged The run-off which is about 215 MHM needsand channellised for meeting the ever growing to be arrested by making proper planning on microrequirement of agriculture, industrial and urban level as well macro level. Microlevel means watergrowth. Moreover exploitation of ground water has conservation schemes of the state governmentsbeen taken up by millions of individual farmers which is to be implemented in every village. But onmostly in regions where surface water is either macro level, a large chunk of water must be arrestedscarce or absent to meet their dire water needs. by programme like national river – linking.Although this has lead to local depletion or decline Availability and utilization of water in India isof ground water levels causing serious concern about shown in table No.1 & Fig. No.1.rainwater harvesting & the need to recharge groundwater. The quantum of ground water so far harnessed Table No. 1is one third of the replenishable ground water of No. Item Quantity431 km3 a year. In the comprehensive strategy (Cu.Kms.)needed for the conservation and development of 1. Annual precipitation volumewater resources, several factors are to be kept in (including snowfall) 4,000view. These include the availability of water, its 2. Average annual potential flowquality, location, distribution and variation in its in rivers 1,869occurrence, climatic conditions, nature of the soil, 3. Per Capita Water availabilitycompeting demands & Socio-economic conditions. (1997) 1,967In dealing with each of these, every effort must be 4. Estimated utilizable water resources 1,122made to make the best use of water for the survival i) Surface water resources 690of human life, animal and plant life. ii) Ground water resources 432 *Lect.in Civil Engg., Govt. Polytechnic, Nanded **Lect.in Civil Engg., Govt. Polytechnic, Washim 31 32. The average annual precipitation is 400 million Hectare Metre (MHM) Evaporates Percolates Run - off 70 MHM 115 MHM 215 MHM Moist soils Enters into the ground water table 65 MHM 50 MHM Fig. 1 : Details of precipitation waterRAINWATER HARVESTING AND ITS have been depicted in the Fig.No.2, Fig.No.3, Fig.TECHNIQUES : No.4. Rain is the ultimate source of fresh waterwith the ground area around houses and buildingsbeing cemented, rain water which run–off fromterraces and roofs was draining into low-lying areasand percolating into the soil and causing floods elsewhere. Rainwater Harvesting is a system by which,rainwater that collects on the roofs and the areaaround buildings is directed into open wells, borewells, tube wells through a filter tank or in to apercolation chamber, built specifically to serve thepurpose. The rain water can be stored in tanks andcan be recharged in to the ground to improve groundwater storage. Fig. No. 2 Roof Top Rainwater Harvesting The storage of rainwater on surface is atraditional technique and the structures used wereunderground tanks, ponds, check dams, percolationwells, weirs etc. Recharge to ground water is a newconcept of rainwater harvesting.There are following three techniques of rainwaterharvesting.a) Storing rain water for direct use.b)
  23. 23. Recharging ground water aquifers, from roof top run off.c) Recharging ground water aquifers with runoff from ground area. Fig. No. 3 Recharging of Bore well The techniques of rainwater harvesting 32 33. Fig. No. 4 Recharging of Open wellWHY RAINWATER HARVESTING ? Following table shows how much roof To meet our water demand, we entirely water can be harvested by considering 80%depend upon rivers, lakes & ground water. However efficiency and according to roof top surface areas.the rain is the ultimate source that feeds all these Roof top Area (Sq.m)sources. The rainfall is highly seasonal and occurs Considering hypothetical case followingover a short rainy season with a very large dry calculations shows as to how much rain water canperiod. As a result, there is a progressive decrease be harvested.in the ground water level. Hence, it should be Consider a building with a flat terrier area =admitted that rain water harvesting is essential 125 Sq.m.because. Average annual gainful in the area is say 1000i) Surface water is inadequate to meet our demand mm (40 inch) and we have to mostly depend on ground water. Suppose, there is no loss of water from theii) Due to rapid urbanization population growth terrace floor, then in one year, there will be and industrialization, improved sanitation, rainwater on the terrace floor to a height of living standard, infiltration of rain water into 1000mm. the sub-soil has decreased drastically and Height of rainfall = 1000 mm, Volume of recharging of ground water has diminished. rainfall = 125 x 1000= 1,25,000 litresiii) Over exploitation of ground water results in to- Assuming that only 80% water harvested.i) Ground water depletion. Volume of water harvested = 1,00,000 litres.ii) Drying up of wells / bore wells. A family of four needs 87,600 litres of wateriii) Enhance use of energy. per year. (@ 60 litres / person)iv) Ingress of sea water in coastal area. It is now alarming to seriously consider ARTIFICIAL GROUND WATERabout conserving water by harvesting and managing RECHARGE :this natural resource by artificially recharging the Optimum development and soundsystem. management practices are vital to the sustained use of ground water. Ground water recharge may beHOW MUCH RAIN WATER CAN BE increased by conservation measures and artificialHARVESTED FROM ROOF TOP ? recharge procedures. Artificial recharge to ground The estimation of water available from top water is a process by which the ground waterof roof (flat terrace) is worked out by multiplying reservoir is augmented at a rate exceeding thatthe roof area with normal rainfall data for monsoon obtaining under natural conditions of replenishment.period. Total quantity of rain water available from In general any man-made system or facility that addsroof top to be used for harvesting is about 70% to water to an aquifer is an artificial recharge system.90%, due to losses like evaporation, absorption, Artificial recharge of ground water is,leakages etc. therefore, preferred and encouraged in the present 33 34. Roof Rain Fall (mm.) top Area 100 200 300 400 500 600 800 1000 (Sq.m) Harvested Water from Roof Top (Cum) @ 80% 20 1.6 3.2 4.8 6.4 8.0 9.6 12.8 16.0 30 2.4 4.8 7.2 9.6 12.0 14.4 19.2 24.0 40 3.2 6.4 9.6 12.8 16.0 19.2 25.6 32.0 50 4.0 8.0 12.0 16.0 20.0 24.0 32.0 40.0 60 4.8 9.6 14.4 19.2 24.0 28.8 38.4 48.0 70 5.6 11.2 16.8 22.4 28.0 33.6 44.8 56.0 80 6.4 12.8 19.2 25.60 32.0 38.4 51.2 64.0 90 7.2 14.4 21.6 28.80 36.0 43.2 57.6 72.0 100 8.0 16 24.0 32.0 40.0 48.0 64.0 80.0 150 12.0 24 36.0 48.0 60.0 72.0 96.0 120.0 200 16.0 32 48.0 64.0 80.0 96.0 128.0 160.0 250 20.0 40 60.0 80.0 100.0 120.0 160.0 200.0 300 24.0 48 72.0 96.0 120.0 144.00 192.0 240.0 400 32.0 64 96.0 128.0 160.0 192.0 256.0 288.0 500 40.0 80 120.0 160.0 200.0 240.0 320.0 400.0 1000 80 160 240 320 400 480 640.0 800.0 2000 160 320 480 640 800 960 1280.0 1600.0days, so as to augment the natural available During wet season, the W.T. rose by, 6-4.8underground yield for management of water supply = 1.2 m., Since 2m lowering of W.T. equals 2M.m3systems. Artificial recharging techniques is under of water, 1.2 m rise will equal to 1.2 M. m3 ofintensive research and is being increasingly used in recharge.France, Israel, U.K. Germany etc.Ex.- Estimation of DIVERSION OF RUN OFF IN TO EXISTINGi) The specific yield of the aquifer and SURFACE BODIESii) The volume of Recharge during the wet season. Construction activity in and around the city/Soln - town is resulting in the drying up of water bodiesConsider, the area of aquifer is 4 km2. and also reclamation of these tanks for conversionWater pummeled out in lowering W.T. i.e. in to plots for houses has impacted urban hydrologyVolume of water drained by 6.8-4.8 = 2m is 2 M.m3 as under.Total Volume of aquifer drained in lowering W.T. 1. Over consumption of water increases waterby 2 m demand. = Area x 2m 2. More dependence on ground water use. = 4x106x2m3 = 8M.m3 3. Increase in run off, decline in well yields and fall in water levels.Specific yield of aquifer S.Y. 4. Reduction in open soil surface area.Specific yield, S.Y.= Volume of water drained x 100 Reduction in infiltration and deterioration of Total volume of aquifer drained water quality. = 2Mm3 x 100 = 25% 8Mm3 34 35. RECHARGING OF UNDERGROUND the permeability of the spread area and on the depthSTORAGE : of water stored, and is generally less, say of the order In order to store the surplus surface water of 1.5m/day, though rates as high as 22m/day havethe artificial surface reservoirs are constructed by been possible.building dams, in the summer, artificial undergroundreservoirs are now-a-days developed by artificial 2. Recharge-well Methods :recharge for storing water underground. This method consists in injecting the waterThe development of such a reservoirs may be in to bore holes called recharge wells. Dependingadvantageous as compared to the development of a upon the favorable condition of surface, the waterdam reservoir, because of the following reasons. is fed in to recharge wells by gravity or for increasingi) Much pure water can be obtained from an the recharge rate, it may be pumped under pressure. underground reservoir source. The recharge wells used are just like ordinaryii) No space is required for building such a production wells. In fact the ordinary wells are reservoir. many a times could directly used for recharge duringiii) The cost of building such a reservoir by the off season, when the water is not required in recharging the aquifers may be considerably use. With this method high recharge rates can be less than the cost of the surface reservoirs. obtained. This method is widely used in Israel. Moreover in an underground reservoir, the Moreover, this method may help in injecting water aquifer in which the water is stored shall itself in to the aquifers and also where it is most needed. act as a distribution system for carrying the To avoid clogging of the well screens, the water water from one place to another, and as such, used for recharging well should be free from the necessity of constructing pipe lines or suspended impurities. canals (as is required in a surface reservoir) is completely eliminated. 3. Induced Infiltration Method :iv) The water lost in evaporation from an This method is sometimes used for recharge