TR-166 : Groundwater balance study in Central Godavari delta of Andhra Pradesh Part 1 Processing and analysis of data

Abstract

History shows that the usual practice in ground water development and utilisation has been to treat the problems and initiate action programmes on an individual, piecemeal basis. Those involved often fail to recognise the benefits of complete management of the ground water resource and its integration into the the total water resource system. Each user has its own goals and these may be inconsistant or even in conflict with the goals of other users in the area. For example, a heavy pumpage of ground water for meeting various water requirements will result in lowering of water table and thereby giving rise to the sea water intrusion problem in coastal aquifers, adverse salt balance and land subsidence where draft results in compaction of sediments. On the other hand, if the recharge exceeds withdrawl, the rising water table may necessiate the planning of conjunctive use. Successful management of ground water, therefore, demands full considerations of all implications of aqufier development, water quality, hydrogeochemical aspects and where appropriate coordinated operation of surface and ground water supplies. The development and management of any ground water basin in a scientific manner involves the ground water balance or hydrological balance analysis as a first step. Ground water balance study enables the assessment of quantity of water available for development and assists in predicting the consequences of artificial changes in the regime of ground water basin. In coastal aquifers having salt water intrusion problems, a fairly accurate estimation on available quantity of fresh water is possible. With water balance data, it is possible to compare individual sources of water in a system over different periods of

time and to establish the degree of their influence on variations in the water regime. Water balance analysis also enables evaluation of one unknown component of water balance equation from all other known components. Keeping the above objectives in mind, the ground water balance study in Central Godavari Delta has been taken up. Since the study involves a variety of data on various aspects such as location, extent, topography, all forms of water inflow and outflow and their quantities, hydrogeology, water quality and agricultural statistics etc, it is planned to collect, compile, analyse and present all the data in one report. The data thus compiled will be helpful in conducting groundwater balance and other relevant studies in future also. The present report is an endeavour in this direction and forms Part I of the Ground Water Balance Study in Central Godavari Delta. The Part II of the study report deals wih the methods of computation of various components of water balance equation and their estimation.