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Definition of drought, Causes of drought, measures for water conservation and augmentation, drought contingency planning. Water harvesting: rainwater collection, small dams, runoff enhancement, runoff collection, ponds, tanks.

 Normal, recurrent feature of climate  Occurs everywhere, vary from region to region.  Originates from deficiency of precipitation.  Impact on ecosystem and agricultural of affected region.  Drought leads to food insecurity, famine, malnutrition, epidemics and displacement of populations.

 Meteorological drought  Agricultural drought  Hydrological drought  Socioeconomic drought

 Reduced rainfall results in drought.  Occurs because water vapour not brought by air currents to right areas at right times.  Unusual currents of cold and warm water in oceans creates high pressure. El Nino causes drought in Asia.  Mountain prevent wind from blowing moisture to needy region.

 In India when water vapour moves from east to west, water vapour does not leave Indian ocean causes drought.  Human activity directly trigger over farming, excessive irrigation, deforestation.  Global warming result in rainfall in some areas and drought in some areas.

 To provide contingency plans to manage drought and emergency conditions.  To continue to deliver a cost effective, adequate, safe and reliable supply of water.  The provision of credit or cash/food for work  Maintaining water supply for animals and humans

 Maintaining cereal availability  Human and livestock health service provision  Support for private sector  Provide fodder for affected stock  Flexible taxation systems for affected people

Drought contingency planning allow for implementation of :  Mitigation  Relief  Rehabilitation

Drought contingency planning for implementation:  Overall drought policy, setting out plans objectives of minimizing the impact of drought  Set plans for specific mitigation, relief and rehabilitation measures  Construction of dams and additional reservoirs for supply of water.  Cloud seeding- artificial rain

 Desalination of sea water for irrigation or consumption.  Drought monitoring by total rainfall levels and total usage levels  Land use by carefully planned crop rotation  Outdoor water use restriction  Rainwater harvesting  Recycled water  Relief works  Disease prevention and control

 Contingency planning done by Govt.  Policy issues, national, regional and district level  rural development infrastructure  input supply, marketing and farm advisory services  Non- Govt.  NGO’S  Rural institutions  Private sectors

 It includes methods for providing an entirely new supply of fresh water and techniques for increasing utility of available supplies of water.  New supply of water include weather modification.  Weather modification done to increase precipitation and decrease Evapotranspiration.  Cloud seeding done to increase precipitation.

Available water supplies increased by conservation of available water supplies.  Agricultural water requirements can be reduced by reducing conveyance losses, and discouraging wasteful irrigation techniques.  Technique should be developed to reduce water consumption in home and industry.  Evaporation losses from small reservoirs can be reduced by providing roofs.

 Reclamation and reuse of waste water can be encouraged.  Evaporation loss in ground water is less. Use of ground water storage reservoir in conjunction with surface storage reservoirs.  Infiltration losses can be reduced by sealing the soil surface useful in arid regions.  Water harvesting done by collecting from roof top, pavements, constructing small storage.

Goals of water conservation efforts include:  Sustainability- ensure availability for future generations  Energy conservation- world 15% energy production dependent on water management.  Habitat conservation- preserve fresh water habitat, migrating waterfowl.

Benefits of water conservation:  Save water save money.  Reduction in excess water use reduce waste water generation, reduce overflowing of gutter.  Ecosystem and habitat protection.  Helps in improving quality of drinking water.

Agricultural (irrigation) conservation  Improved irrigation methods such as sprinklers or drip irrigation.  Water required for agricultural considerably reduced by reducing conveyance loss.  Evaporation losses from small reservoirs can be reduced by providing roofs over them.  Use of lined canals which reduce seepage and evaporation.

 Use of ground water storage reservoir in conjunction with modern surface storage reservoirs to reduce evaporation loss, in arid regions.  Price agricultural water to encourage conservation.  Infiltration losses reduced by sealing soil surface.  Water harvesting in arid regions.

For conservation of water the following structures can be constructed:  Earthen bund  Gully plugging  Check dam  Khet talawadi

Earthen bund

Gully plugging

Check dam

Khet Talawadi

 Collection of rain water called water harvesting.  Rainwater harvesting is accumulation and storing of rainwater for reuse, before it reaches aquifer.  Water collected from roofs of houses, schools, local institutions make important contribution.  Water collected from ground, called storm water harvesting.

Benefits of rainwater harvesting  Increase water availability  Checks declining water table  Environmental friendly  Improves water quality of ground water  Surface water runoff conservation  Prevents soil erosion and flooding in urban area

Rainwater harvesting technique  Rainwater collection – Roof top rainwater harvesting  Runoff collection – Surface runoff harvesting  Recharge to ground water  Runoff enhancement

 Rainwater captured from roof catchments and stored in sub surface ground water reservoir.  Objective is to make water available for future use.  Useful in dry land, hilly, urban and costal areas.

Components of roof top rainwater harvesting  a collection area  a conveyance system  storage facility  a delivery system  Storage reservoir expensive part, careful design and construction required.  First rainwater should be flushed or diverted.

 Surface runoff harvesting is traditional technique.  Small dams, ponds, tanks are used.  Used for irrigation, domestic, livestock use.

Small dams  Small dams/check dams constructed in natural channel to impound the runoff water up to certain depth.  Impounded water slowly infiltrate into soil and recharge ground water.

Ponds and reservoirs  Impounding type and dug-cut type ponds constructed.  In impounding type, a retaining wall or dam is constructed to block the flow of water in a natural storm.  In dug-cut type area is excavated to store the runoff.  Reservoirs requires water storage area, spillways and earth embankment.

Storage tank  Surface or above ground tank  Subsurface or underground tank Storage tanks require  Solid secure cover  Coarse inlet filter  Overflow pipe  Manhole, sump and drain to facilitate cleaning  Outlet system, tap or pump

The structures generally used:  Pits  Trenches  Dug well  Hand pumps  Recharge well  Spreading techniques  Underground reservoirs