'HARNESSING OF WATER RESOURCES IN MANDOVI-ZUARI ESTUARIES OF GOA

Abstract

The primary objective of any water resource project is to provide adequate water for domestic, agricultural, industrial, recreational or power generation purposes at optimum cost. The heavy rainfall during South-west monsoon precipitating on hill ranges of.western ghats and flowing westwards drain into Arabian sea with very small utilization which could be attributed to very short length of estuaries and prominent prevalence of saline water due to tidal effect. The precipitated water during South-west monsoon in the state like Goa, Maharashtra, Karnataka etc. is required to be harnessed as a fresh water resource by constructing low crested gated weirs in tidal reaches. ID mathematical model studies have been carried out with hydraulic, hydrologic and hydrographic data available at CWPRS for Manovi — Zuari estuaries in Goa state. The hydraulic model studies revealed that the effective live storage on upstream side of gated weirs would be about 50Mcum if it is stored at +4.Om above chart datum and it would be more than 8OMcum if it is stored at +6.Om above chart datum. The effective live storage is between high water level (+2.5M) and the proposed level to be stored. viz. +4.Om or +6.0m above chart datum. The storage would be quite sufficient and it can be used repeatedly in monsoon after consumption, also it would satisfy water requirements in some part of non-monsoon also. The water level, velocities and time of storage in Mandovi river, and Cumbarjua canal for different discharges and tides with different conditions of gate openings are observed to be within acceptable limits. It seems that the proposal of harnessing fresh water in Mandovi-Zuari estuaries can be taken up in future to meet - increasing domestic, agricultural, tourist and industrial demand of water in Goa state to a remarkable extent. The enhancement in surface water resources in Mandovi —Zuari estuaries would help in replenishment of ground water recharge, which may be explored and would found to be appreciable quantity. Further hydraulic model studies for the proposal should be accompanied with proper geological, geo-morphological and environmental studies.