Integrated Watershed Management& Rainwater Harvesting Prof. T. I. Eldho , Department of Civil Engineering, Indian Institute of Technology Bombay/ India.•Contents• India’s Water Resources• Watershed Development & Modelling• Integrated Watershed Management• Water Conservation & Harvesting• Successful Case Study
Integrated Water Resources Development andManagement: IWRDM.Integration of -- River basin resources- surface and ground.- Demands - consumptive and non-consumptive,and supplies.- Facilities - mega to micro.- Human and eco-systems.- S&T and engineering with social, economic,synergic needs.
INDIA’S LAND RESOURCE, IRRIGATIONAND FOOD PRODUCTION• India has 2% of world’s land, 4% of freshwater, 16% ofpopulation, and 10% of its cattle.• Geographical area = 329 Mha of which 47% (142 Mha) iscultivated, 23% forested, 7% under non-agri use, 23%waste.• Per capita availability of land 50 years ago was 0.9 ha,could be only 0. 14 ha in 2050.• Out of cultivated area, 37% is irrigated which produces55% food; 63% is rain-fed producing 45% of 200 M t offood.• In 50 years (ultimate), proportion could be 50:50producing 75:25 of 500 M t of required food.
SOME INFERENCES FROM RIVER BASIN STATISTICS• Himalayan Rivers Water: 300 utilizable, 1200 BCMavailable.• Himalayan large dams presently store 80 BCM. Newdams under consideration could store 90 BCM.• Peninsular Rivers Water: 400 utilizable, 700 BCMavailable.• Peninsular large dams presently store 160 BCM. Newdams under consideration could store 45 BCM.• In all, large dams presently store 240 BCM. Newdams under consideration could store 135 BCM. Totalstorage thus could be 375 BCM only.
WITHDRAWAL OF WATER- 2050, AVAILABILITYIndia’s Yearly Requirement in 2050 (Km3 = BCM)• For growing food and feed at 420 to 500 million tonnes = 628 to 807 BCM• Drinking water plus domestic and municipal use for rural population at150 lpcd and for urban population at 220 lpcd = 90 to 110 BCM•Hydropower and other energy generation = 63 to 70 BCM•Industrial use = 81 to 103 BCM•Navigational use = 15 BCM•Loss of water by evaporation from reservoirs = 76 BCM•Environment and ecology = 20 BCMTotal 970 to 1200 BCMAvailability 1100 to 1400 BCM
Where does the water come from?•New dams - inter-basin transfer•Groundwater - underdeveloped•Demand Management•Water savings - increase in efficiency,reduce evaporation.•Water productivity - increases in crop perdrop•Trade (virtual water), import food.
Part 2: Watershed Development & ModellingLimited water resources,-more demand.Watershed is the basic scientific unit. Need for proper planning and management.Integrated watershed development approach Digital revolution Recent advances in watershed modelling - use of computer models, remote sensing and GIS.
WATERSHED Development …Parameters of Watershed• Size•Shape•Physiography•Climate•Drainage•Land use•Vegetation•Geology and Soils•Hydrology•Hydrogeology•Socioeconomics
WATERSHED MODELLING …Watershed modelling steps 1. Formulation 2. Calibration/verification 3. ApplicationWatershed model constitutes 1. Input function 2. Output function 3. Transform function
WATERSHED MODELLING … Precipitation ET Interception ET Storage Surface Storage Surface Runoff Infiltration Interflow Direct Runoff Percolation Baseflow Groundwater Channel Storage Processes Fig Flowchart of simple watershed model (McCuen, 1989)
WATERSHED MODELLING … General Classification of ModelsBroadly classified into three typesBlack Box Models: These models describe mathematically therelation between rainfall and surface runoff without describingthe physical process by which they are related.e.g. Unit Hydrograph approachLumped models:These models occupy an intermediate position between thedistributed models and Black Box Models. e.g. StanfordWatershed ModelDistributed Models:These models are based on complex physical theory, i.e. basedon the solution of unsteady flow equations.
Part 3: Integrated Watershed Management Background • Large water resources development projects in India have adverse socio-economic and environmental consequences. • The failure of such projects, contributed to indebtedness, raising economic pressure and jeopardising future development. • Indiscriminate expansion of marginal lands and over-utilisation of existing water resources for irrigation. • Traditional water harvesting systems have suffered sever neglect. • This type of development not only called into question • the adequacy of water resources schemes but triggered the urgent • search for more effective and appropriate management strategies. • Major response to follow “Integrated Watershed Management Approach”.
Concepts and Principles of IWMObjectives: Water has multiples uses and must be managed in an integrated way. Water should be managed at the lowest appropriate level. Water allocation should take account of the interests of all who are affected. Water should be recognised and treated as an economic good.Strategies: A long term, viable sustainable future for basin stake holders. Equitable access to water resources for water users. The application of principles of demand management for efficient utilisation. Prevention of further environmental degradation (short term) and the restoration of degraded resources (long term). .Implementation Programs: Comprise an overall strategy that clearly defines the management objectives, a delivery mechanisms and a monitoring schedule that evaluates program performance. Recognise that the development of water resources may require research, to assess the resource base through modelling and development of DSS, and to determine the linkage between water resources and the impacts on environment, socio-economy. Ensure that mechanisms and policies are established that enables long term support.
Integrated Watershed ApproachIWM is the process of planning and implementing water and naturalresources …… an emphasis on integrating the bio-physical, socio-economicand institutional aspects. High water conservation, Project success Socio-economic with water conservation Public Participation Socio-economic, Public participation participation planning, design, implementation Mainly water conservation Low 1970 1980 1990 2000 Watershed development programSocial issues are addressed through involvement of women and minority.Community led water users groups have led the implementation efforts.
•The four engineering and management tools foreffective and sustainable development of waterresources in semi-arid rural India: - • Appropriate technologies • Decentralised development system • Catchment based water resources planning • Management information system•In past the efforts were more on the soil conservation andtaking measures on the land where as we used to neglect thewelfare of the land users.• For sustainable watershed management there is needto integrate the social and economic development togetherwith soil and water conservation
Part 4: Water Conservation &Harvesting Total water management for sustainable development?.
Water Conservation Important step for solutions to issues of water and environmental conservation is to change peoples attitudes and habits Conserve water because it is right thing to do!. What you can do to conserve water? Use only as much water as you require. Close the taps well after use. While brushing or other use, do not leave the tap running, open it only when you require it. See that there are no leaking taps. Use a washing machine that does not consume too much water. Do not leave the taps running while washing dishes and clothes.
Water Conservation… Install small shower heads to reduce the flow of the water. Water in which the vegetables & fruits have been washed - use to water the flowers & plants. At the end of the day if you have water left in your water bottle do not throw it away, pour it over some plants. Re-use water as much as possible Change in attitude & habits for water conservation Every drop counts!!!
Rain Water Harvesting?.• Rain Water Harvesting RWH- process of collecting,conveying & storing water from rainfall in an area – forbeneficial use.• Storage – in tanks, reservoirs, underground storage-groundwater• Hydrological Cycle
Rain Water Harvesting?.• RWH - yield copious amounts of water. For anaverage rainfall of 1,000mm, approximately four millionlitres of rainwater can be collected in a year in an acreof land (4,047 m2), post-evaporation.•As RWH - neither energy-intensive nor labour-intensive•It can be a cost-effective alternative to other water-accruing methods.• With the water table falling rapidly, & concretesurfaces and landfill dumps taking the place of waterbodies, RWH is the most reliable solution foraugmenting groundwater level to attain self-sufficiency
RWH – Methodologies• Roof Rain Water Harvesting• Land based Rain Water Harvesting• Watershed based Rain Water harvesting • For Urban & Industrial Environment – • Roof & Land based RWH • Public, Private, Office & Industrial buildings • Pavements, Lawns, Gardens & other open spaces
Rain Water Harvesting– Advantages1.Provides self-sufficiency to water supply2.Reduces the cost for pumping of ground water3.Provides high quality water, soft and low in minerals4.Improves the quality of ground water throughdilution when recharged5.Reduces soil erosion & flooding in urban areas6.The rooftop rain water harvesting is less expensive& easy to construct, operate and maintain7. In desert, RWH only relief8. In saline or coastal areas & Islands, rain waterprovides good quality water
Part 5: Successful Case Study Catchment Area = 1800 km2
Jhabua Watershed: Case StudyMadhya Pradesh ( INDIA ), ~ altitude of 380 m to540 m. Area – 1800 sq.km Highly undulating, sparsely distributed forest cover. ~ 57% arable land including cultivable fellow and ~ 18% notified as forest land. Average rainfall ~ 750 mm per annum.~ 20-30 events during June-September~ Classified as drought prone region. Moisture deficit during January to May months each year.
Jhabua watershed: Case studyMajor crops:Maize, Cotton, Peanuts,Soyabeans;Gram, Black beans, Oilseeds. Predominantly tribal population, 92% engaged in agriculture. ~ high seasonal migration ~ economically one of the most backward district
Yearly rainfall departure from the mean for rainfall stationJhabua Seasonal rainfall departure are extremely variable.
Development Issues•Subsistence of rain-fed mono-cropping farmingsystem with low agriculture productivity•Undulating topography and soil erosion due toovergrazing causing degradation of land.•High pressure of population on the agricultureland leading to substantial poverty causingimmigration.•Absence of decentralized water resources andbasic infrastructure facilities.•Degradation of forestry land due to absence ofcommunity involvement in protection of the forest.
Planning & ImplementationA Three step IWMA model approach1. Resources Mapping using Geographical Information System2. Appropriate Technology3. Management Information System
Resources mapping: Ground water dynamics Total alluvium area= 18.5 km2 Channel porosity = 20% Depth of wetting front = 4.0 m Total storage capacity = 14.8 x106 m3.
Resources mapping: Surface water storage Reservoir in main channel Total number of reservoirs = 144 Storage capacity = 81.3 x 106 m3
Appropriate Technology Water conservation and groundwater recharge techniques Water harvesting cum supplementary irrigation techniques in Jhabua
Water ConservationWater conservation interventions includescontour trenches, gully plugging, vegetativeand field bunding, percolation tanks.Overall land treatment against potential area is varying between 40-60%. Type of land ownership for soil 2% 5% and water conservation 28% measures 25% 65% 45% Contour bunding Gully plugging Staggered trenching Level terraces 30% Private land Fallow land Forest land Techniques of soil and water conservation measures
Joint Forest ManagementRedevelopment of forest is essential for catering socio-economics needs of the people and ecological needsof the region.Forest committees are formed for forest protection andpart of area is made available for grazing on rotationbasis. Implementing agencies promoted the concept of “Social Fencing” people protecting the forest and grazing land.
Community participation and local capacity buildingDevelopment of new village level institutions and local capacity building.Operation & maintenance of structures, regulation of financial matters, andconflict resolution.
DiscussionSuccess interventions reside in integration of appropriate technical andmanagerial measures.People’s participation in the entire process are most important.The benefits of water harvesting and water conservation definitely reached.Efficient utilisation of funds, only 10-15% spent on non-project costs.Thus, IWM approach may be characterised by •Community management built on existing social structure, •Project management drawn from village level organisations, •Joint forest management with community participation, •Self-help water user groups and community based banking institutions.Limitation: 100% drought proofing for every water use can not be achieved.
Concluding RemarksThe integrated watershed management approachhave the following major components: • Promote sustainable economic development through optimum utilisation of natural resources and local capacity building. • Restore ecological balance through community participation and cost affordable technologies for easy acceptance. • Improving living conditions of the poorer through more equitable resources distribution and greater access to income generating activities.
Concluding Remarks• About 2-4 meter water level increase is observed in selected wells.• Watershed management can easily cope with climate change impacts.• The benefits of water harvesting and water conservation not only for drinking water security but also for agriculture definitely reached.•Efficient utilisation of funds as only 10-15% of the total budgetspent on non-project costs.• Water security through IWM
Dr. T. I. EldhoAssociate Professor,Department of Civil Engineering,Indian Institute of Technology Bombay,Mumbai, India, 400 076.Email: email@example.comPhone: (022) – 25767339; Fax: 25767302http://www.civil.iitb.ac.in