Superintending Hydrogeologist, Central Ground Water Board, Faridabad, India
Online published on 11 December, 2012.
Total annual utilizable water resource in India is around 1123 BCM constituting only 28% of the precipitation received in the country. This provides a large scope for harvesting the huge quantum of precipitation which otherwise goes waste as runoff and remains unutilized. The sub-surface reservoirs are very attractive and technically feasible alternatives for storing surplus monsoon run off as they can store substantial quantities of water. The sub-surface geological formations may be considered as “warehouse” for storing water that comes from sources located on the land surface. Besides suitable litho logical condition, other considerations for creating sub-surface storages are favourable geological structures and physiographic units, whose dimensions and shape will allow retention of substantial volume of water in porous and permeable formations.
Besides raising ground water levels, recharge of surplus runoff also helps in mitigating flash floods, soil erosion and silting of reservoirs and rivers. The effluence resulting from such sub-surface storage at various surface intersection points in the form of spring line, or stream emergence, would enhance the river flows and improve the presently degraded ecosystem of riverine tracts, particularly in the outfall areas.
It is estimated that annually about 36 BCM of surplus surface run-off can be recharged to augment the ground water. The artificial recharge potential can be effectively and efficiently harnessed by adopting appropriate artificial recharge techniques which is generally referred as managed aquifer recharge. There are various techniques used for artificial recharge to ground water, however the techniques broadly fall under the categories of Surface Spreading Techniques and Sub-surface Techniques. Aquifer disposition plays a decisive role in choosing the appropriate technique of artificial recharge of ground water. The technical expertise and willingness on the part of government agencies and other stake holders has grown many fold in the last couple of decades for construction of artificial recharge structures both in rural and urban areas. There are many success stories reported and being recognised across the country to motivate greater community participation and involvement of stakeholders in the activities of construction, management operation and monitoring of artificial recharge as well as water conservation projects.
The ground water use may be substantially enhanced to support the required agricultural development and to improve the rural livelihoods in the country apart from meeting the urban water supply demand. Aquifer maps should be the foremost bases for identifying the potential recharge zones in overexploited areas. There is a pressing need of adequate scientific understanding for artificial recharge and for formulation of appropriate strategy to utilize geosciences as irreplaceable tools. Design of suitable site-specific recharge structures on unpolluted stream water drains, open areas, parks and playgrounds is the key to raise the ground water table and ensure safe water quality. Capacity building of the Community/Gram Panchayat/Water User Association/and their involvement in implementation and maintenance is essential in the national programme for managed aquifer recharge. Participatory ground water management is also needed to make the country self reliant in the water and food security front.
