rain water harvesting

1. Integrated Watershed Management & Rainwater Harvesting Prof. T. I. Eldho ,Department of Civil Engineering,Indian Institute of Technology Bombay/ India.

Contents

Indias Water Resources

Watershed Development & Modelling

Integrated Watershed Management

Water Conservation & Harvesting

Successful Case Study

2. Integrated Water Resources Development and Management: 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. 3.

INDIAS LAND RESOURCE, IRRIGATION

AND FOOD PRODUCTION

India has 2% of worlds land, 4% of freshwater, 16% of population, and 10% of its cattle.

Geographical area = 329 Mha of which 47% (142 Mha) is cultivated, 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 produces 55% food; 63% is rain-fed producing 45% of 200 M t of food.

In 50 years (ultimate), proportion could be 50:50 producing 75:25 of 500 M t of required food.

SOME INFERENCES FROM RIVER BASIN STATISTICS

Himalayan Rivers Water: 300 utilizable, 1200 BCM available.

Himalayan large dams presently store 80 BCM. New dams under consideration could store 90 BCM.

Peninsular Rivers Water: 400 utilizable, 700 BCM available.

Peninsular large dams presently store 160 BCM.New dams under consideration could store 45 BCM.

In all, large dams presently store 240 BCM.New dams under consideration could store 135 BCM.Total storage thus could be 375 BCM only.

WITHDRAWAL OF WATER- 2050, AVAILABILITY

Indias Yearly Requirement in 2050 (Km 3= 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 at 150 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 BCM

Total 970 to 1200 BCM

Availability 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 per drop

Trade (virtual water), import food.

7. Part 2: Watershed Development & Modelling

L imited 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 ofcomputer models, remote sensingand GIS.

8. WATERSHED Development

Watershed Characteristics.

Hydrology of watershed .

Watershed Sub-watershed Milli- watershed Micro-watershed Mini-watershed 50,000-2,00,000 10,000-50,000 1,000-10,000 100-1,000 10-100 Classification Watershed (ha) 9. WATERSHED Development

Parameters of Watershed

Physiography

Climate

Drainage

Land use

Vegetation

Geology and Soils

Hydrology

Hydrogeology

Socioeconomics

10. WATERSHED MODELLING Watershed modellingsteps 1. Formulation 2. Calibration/verification3. ApplicationWatershed model constitutes 1. Input function 2. Output function3. Transform function 11. FigFlowchart of simple watershed model (McCuen, 1989) WATERSHED MODELLING Precipitation Interception Storage Surface Runoff Groundwater Storage Channel Processes Interflow Direct Runoff Surface Storage Baseflow Percolation Infiltration ET ET 12. WATERSHED MODELLING General Classification of Models Broadly classified into three types Black Box Models: These models describe mathematically the relation between rainfall and surface runoff without describing the physical process by which they are related.e.g. Unit Hydrograph approach Lumped models: These models occupy an intermediate position between the distributed models and Black Box Models.e.g. Stanford Watershed ModelDistributed Models: These models are based on complex physical theory, i.e. based on the solution of unsteady flow equations. 13. Background

Large water resources development projects in India

haveadverse socio-economic and environmental consequences .

The failure of such projects, contributed toindebtedness ,

raisingeconomic pressureand jeopardising future development.

Indiscriminateexpansion of marginal landsandover-utilisation

of existing water resourcesfor irrigation.

Traditionalwater harvesting systemshave suffered sever neglect.

This type of development not only called into question

theadequacy of water resources schemesbut triggered the urgent

search for moreeffective and appropriate management strategies .

Major response to follow Integrated Watershed Management Approach .

Part 3:Integrated Watershed Management 14. Concepts and Principles of IWM Objectives: Water hasmultiples usesand must be managed in an integrated way. Water should be managed at thelowest appropriate level . Water allocation should takeaccount of the interests of allwho are affected. Water should be recognised and treated as an economic good. Strategies: A long term, viablesustainable futurefor basin stake holders. Equitable access to water resources for water users. The application ofprinciples of demand managementfor efficient utilisation. Prevention of furtherenvironmental degradation(short term) and the restoration ofdegraded resources (long term). . Implementation Programs: Comprise an overall strategy that clearly defines the management objectives, a delivery mechanisms and amonitoring schedulethat evaluatesprogram performance . Recognise that the development of water resources may require research, to assess theresource base throughmodelling and development of DSS , and to determine thelinkage between water resources and theimpacts on environment, socio-economy . Ensure that mechanisms and policies are established that enables long term support. 15. Integrated Watershed Approach IWM is the process of planning and implementing water and natural resources an emphasis on integrating the bio-physical, socio-economic and institutional aspects.Social issues are addressed throughinvolvement of women and minority .Community ledwater users groupshave led the implementation efforts.1970 1980 1990 2000 Public Participation Watershed development program Low High Mainly waterconservation Socio-economic withwater conservation Socio-economic,water conservation, participation Public participationplanning, design,implementation Project success 16.

The four engineering and management tools for effective and sustainable development of water resources 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 and taking measures on the land where as we used to neglect the welfare of the land users.

F or sustainable watershed managementthere is need to integrate the social and economic development together with soil and water conservation

17. IWA Modeling through Advanced Technologies 18. Part 4: Water Conservation & Harvesting Total water management for sustainable development ?. 19. Water Conservation

Important step for solutions to issues of water and environmental conservation is to change people's 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.

20. 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!!!

21. Rain Water Harvesting?.

Rain Water Harvesting RWH- process of collecting, conveying & storing water from rainfall in an area for beneficial use.

Storage in tanks, reservoirs, underground storage- groundwater

Hydrological Cycle

22. Rain Water Harvesting?.

RWH - yield copious amounts of water. For an average rainfall of 1,000mm, approximately four million litres of rainwater can be collected in a year in an acre of land (4,047 m 2 ), post-evaporation.

A s 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, & concrete surfaces and landfill dumps taking the place of water bodies, RWH is the most reliable solution for augmenting groundwater level to attain self-sufficiency

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 openspaces

RWH Methodologies 24. Rain Water Harvesting Advantages1.Provides self-sufficiency to water supply2.Reduces the cost for pumping of ground water 3.Provides high quality water, soft and low in minerals 4.Improves the quality of ground water through dilution when recharged 5.Reduces soil erosion & flooding in urban areas 6.The rooftop rain water harvesting is less expensive &easy to construct, operate and maintain 7. In desert, RWH only relief8.I n saline or coastal areas & Islands, rain water provides good quality water 25. Part 5: Successful Case Study Catchment Area = 1800 km 2 26. Jhabua Watershed: Case Study

Madhya Pradesh ( INDIA ),~ altitude of 380 m to 540 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 deficitduring Januaryto May months each year. 27. Jhabua watershed: Case study Major crops:Maize, Cotton, Peanuts, Soyabeans; Gram, Black beans, Oil seeds.Predominantly tribal population, 92% engaged in agriculture. ~high seasonal migration ~ economically one of themost backward district 28. Yearly rainfall departure from the mean for rainfall station Jhabua Seasonal rainfall departure are extremely variable. 29.

Subsistence of rain-fed mono-cropping farming system with low agriculture productivity

Undulating topography and soil erosion due to overgrazing causing degradation of land.

High pressure of population on the agriculture land leading to substantial poverty causing immigration.

Absence of decentralized water resources and basic infrastructure facilities.

Degradation of forestry land due to absence of community involvement in protection of the forest.

Development Issues 30. Planning & Implementation

AThree step IWMA model approach

Resources Mapping using Geographical Information System

Appropriate Technology

Management Information System

31. Resources mapping: Ground water dynamics Total alluvium area= 18.5 km 2 Channel porosity = 20% Depth of wetting front = 4.0 m Total storage capacity = 14.8 x10 6m 3. 32. Resources mapping: Surface water storage Total number of reservoirs = 144 Storage capacity = 81.3 x 10 6m 3 Reservoir in main channel 33. Appropriate Technology Water conservation and groundwater recharge techniques Water harvesting cum supplementary irrigation techniques in Jhabua 34. Water Conservation Water conservation interventions includes contour trenches,gully plugging, vegetative and field bunding, percolation tanks.Overall land treatment against potential area is varying between 40-60%.Type of land ownership for soil and water conservation measuresTechniques of soil and water conservation measures 35. Redevelopment of forest is essential for catering socioeconomics needs of the people and ecological needsof the region.Forest committeesare formed for forest protection and part of area is made available for grazing on rotation basis.Implementing agencies promoted the concept ofSocial Fencingpeople protecting the forest and grazing land.Joint Forest Management 36. Community participation and local capacity building Development of new village level institutions and local capacity building.Operation & maintenance of structures, regulation of financial matters, and conflict resolution. 37. Discussion Success interventions reside inintegration of appropriate technical and managerial measures .Peoples 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.Limitation:100% drought proofing for every water use can not be achieved.Thus,IWM approachmay be characterised by

Community management built onexisting social structure ,

Project management drawn fromvillage level organisations ,

Joint forest management withcommunity participation ,

Self-help water user groups and community based banking institutions.

38. Concluding Remarks The integrated watershed management approachhave the following major components:

Promotesustainable economic developmentthrough optimum

utilisation of natural resources and local capacity building.

Restoreecological balancethrough community participation

and cost affordable technologies for easy acceptance.

Improvingliving conditionsof the poorer through more equitable

resources distribution and greater access to income

generating activities.

39. Concluding Remarks

Water security through IWM

Efficient utilisation of fundsas only 10-15% of the total budget

spent on non-project costs.

The benefits of water harvesting and water conservation not only for

drinking water security but also for agriculture definitely reached.

About 2-4 meter water level increase is observed in selected wells.

Watershed management can easily cope withclimate change impacts .

40. Dr. T. I. Eldho Associate Professor, Department of Civil Engineering,Indian Institute of Technology Bombay, Mumbai, India, 400 076.Email:[email_address] Phone: (022) 25767339; Fax: 25767302 http://www. civil.iitb.ac.in