Water Resources Planning

Water resources development and management will have to be planned for a hydrological unit such as a drainage basin as a whole or a sub-basin. Apart from traditional methods, non-conventional methods for utilization of water should be considered, like

•         Inter-basin transfer

•         Artificial recharge of ground water

•         Desalination of brackish sea water

•         Roof-top rain water harvesting

The above options are described below in some detail:

Inter-basin transfer:

Basically, it's the movement of surface water from one river basin into another. The actual transfer is the amount of water not returned to its source basin. The most typical situation occurs when a water system has an intake and wastewater discharge in different basins. But other situations also cause transfers. One is where a system's service area covers more than one basin. Any water used up or consumed in a portion of the service area outside of the source basin would be considered part of a transfer (e.g. watering your yard). Transfers can also occur between interconnected systems, where a system in one basin purchases water from a system in another basin.

Artificial recharge of ground water:

Artificial recharge provides ground water users an opportunity to increase the amount of water available during periods of high demand--typically summer months. Past interest in artificial recharge has focused on aquifers that have declined because of heavy use and from which existing users have been unable to obtain sufficient water to satisfy their needs.

Desalination of brackish sea water:

Water seems to be a superabundant natural resource on the planet earth. However, only 0.3 per cent of the world's total amount of water can be used as clean drinking water. Man requires huge amounts of drinking water every day and extracts it from nature for innumerable purposes. As natural fresh water resources are limited, sea water plays an important part as a source for drinking water as well. In order to use this water, it has to be desalinated. Reverse osmosis and electro dialysis is the preferred methods for desalination of brackish sea water.

Roof-top rain water harvesting:

In urban areas, the roof top rain water can be conserved and used for recharge of ground water. This approach requires connecting the outlets pipe from roof top to divert the water to either existing well/tube wells/bore wells or specially designed wells/ structures. The Urban housing complexes or institutional buildings have large roof area and can be utilized for harvesting the roof top rain water to recharge aquifer in urban areas.

One important concept useful in water resources planning is Conjunctive or combined use of both surface and ground water for a region has to be planned for sustainable development incorporating quantity and quality aspects as well as environmental considerations. Since there would be many factors influencing the decision of projects involving conjunctive use of surface and ground water, keeping in mind the underlying constraints, the entire system dynamics should be studied to as detail as practically possible. The uncertainties of rainfall, the primary source of water, and its variability in space and time has to be borne in mind while deciding upon the planning alternatives.

It is also important to pursue watershed management through the following methodologies:

•         Soil conservation This includes a variety of methods used to reduce soil erosion, to prevent depletion of soil nutrients and soil moisture, and to enrich the nutrient status of a soil.

•         Catchment area treatment Different methods like protection for degradation and treating the degraded areas of the catchment areas, forestation of catchment area.

•         Construction of check-dams Check-dams are small barriers built across the direction of water flow on shallow rivers and streams for the purpose of water harvesting. The small dams retain excess water flow during monsoon rains in a small catchment area behind the structure. Pressure created in the catchment area helps force the impounded water into the ground. The major environmental benefit is the replenishment of nearby groundwater reserves and wells. The water entrapped by the dam, surface and subsurface, is primarily intended for use in irrigation during the monsoon and later during the dry season, but can also be used for livestock and domestic needs.