Tools for water resources planning and management

The policy makers responsible for making comprehensive decisions of water resources planning for particular units of land, preferably a basin, are faced with various parameters, some of  which are discussed in the following sections.

The supply of water

Water available in the unit

This may be divided into three sources

•         Rain falling within the region. This may be utilized directly before it reaches the ground, for example, the roof – top rain water harvesting schemes in water scarce areas.

•         Surface water bodies. These static (lakes and ponds) and flowing (streams and rivers), water bodies may be utilized for satisfying the demand of the unit, for example by constructing dams across rivers.

•         Ground water reservoirs. The water stored in soil and pores of fractured bed rock may be extracted to meet the demand, for example wells or tube – wells.

Water transferred in and out of the unit

If the planning is for a watershed or basin, then generally the water available within the basin is to be used unless there is inter basin water transfer. If however, the unit is a political entity, like a nation or a state, then definitely there shall be inflow or outflow of water especially that of flowing surface water. Riparian rights have to be honored and extraction of more water by the upland unit may result in severe tension.

Note: Riparian rights mean the right of the downstream beneficiaries of a river to the river water.

Regeneration of water within the unit

Brackish water may be converted with appropriate technology to supply sweet water for drinking and has been tried in many extreme water scarce areas. Waste water of households may be recycled, again with appropriate technology, to supply water suitable for purposes like irrigation.

The demand of water

Domestic water requirement for urban population

This is usually done through an organized municipal water distribution network. This water is generally required for drinking, cooking, bathing and sanitary purposes etc, for the urban areas. According to National Water Policy (2002), domestic water supplies for urban areas under various conditions are given below. The units mentioned “lpcd” stands for Liters per Capita per Day”.

•         40 lpcd where only spot sources are available

•         70 lpcd where piped water supply is available but no sewerage system

•         125 lpcd where piped water supply and sewerage system are both available. 150 lpcd may be allowed for metro cities.

Domestic and livestock water requirement for rural population

This may be done through individual effort of the users by tapping a local available source or through co-operative efforts, like Panchayats or Block Development Authorities. The accepted norms for rural water supply according to National Water Policy (2002) under various conditions are given below.

•         40 lpcd or one hand pump for 250 persons within a walking distance of 1.6 km or elevation difference of 100 m in hills.

•         30 lpcd additional for cattle in Desert Development Programme (DDP) areas.

Irrigation water requirement of cropped fields

Irrigation may be done through individual effort of the farmers or through group cooperation between farmers, like Farmers’ Cooperatives. The demands have to be estimated based on the cropping pattern, which may vary over the land unit due to various factors like; farmer’s choice, soil type, climate, etc. Actually, the term “Irrigation Water Demand” denotes the total quantity and the way in which a crop requires water, from the time it is sown to the time it is harvested.

Industrial water needs

This depends on the type of industry, its magnitude and the quantity of water required per unit of production.