The report gives the groundwater potential of different districts of the State on watershed basis and also information about the semi-critical, critical and over-exploited watersheds.
This report on “Dynamic Ground Water Resources of Maharashtra (2004)” presents the groundwater estimates for the State of Maharashtra as computed by the Central Ground Water Board (CGWB) and Groundwater Survey and Development Agency (GSDA) based on the guidelines given by the Groundwater Estimation Committee (GEC-1997) constituted by Ministry of Water Resources (Government of India).
The report is structured as follows -
Chapter 1: Introduction
Chapter 2: About Maharashtra
Chapter 3: Ground Water Resource Estimation Methodology, 1997
Chapter 4: Computation of groundwater resources in the State
Justification for reduction in recharge
For the purpose of groundwater estimation and evaluation the State was divided into 1505 elementary watersheds. The recharge was estimated for the groundwater worthy area of all the watersheds while the non-worthy area comprising of steep slopes more than 20 per cent, hill tops and rock waste have been left out. Each watershed was further delineated into groundwater poor quality area, where the quality of the groundwater was beyond the usable limits as also into command and non-command area. Likewise each watershed was divided into three assessment subunits. But all the subunits were not present in the single watershed. Hence, the assessment was carried out on a watershed basis, although initially the assessment was carried out for the command and non-command areas.
The groundwater resource estimation of Maharashtra for the year 2004 based on the GEC 1997 guidelines indicates that –
- Out of the total area under irrigation, 28.75 lakh hectares (71 per cent) is irrigated by groundwater and 11.83 lakh hectares (29 per cent) is served by flow/canal irrigation. Out of the total groundwater consumed, 85 per cent is for irrigation, 10 per cent is for industries and only 5 per cent is for domestic consumption. Drinking water needs of 90 per cent of the total rural population are entirely met from groundwater.
- The total rechargeable groundwater resource in the State is computed as 32,96,109 hectare meter (ham) or (32.96 BCM) and the net groundwater availability is 31,21,404 hectare meter (ham) or (31.21 BCM).
- Out of these, 1,50,883 ham or 1.51 BCM is earmarked for domestic and industrial requirement and the remaining is available for future irrigation.
- Between 1988 and 2004, the groundwater use has increased by 4.03 ham (i.e. from 11.05 to 15.09 BCM).
- The present irrigation draft is to the tune of 14.24 BCM, leaving behind a fairly good groundwater balance.
- Unfortunately, major part of the groundwater balance exists in the areas where development is not required for either irrigation or for drinking and/or is in areas, which are not favorable for development. It is observed that the draft figure is not accurate (much less than actual) because except for Latur and Osmanabad, the draft from irrigation borewells/tubewells has not been accounted for. It is a well-known fact that large number of irrigation borewells/ tubewells are the main source of irrigation in all the parts of the State and large number of them are not on record for electricity connections. If draft from those borewells/tubewells had been accounted for then the balance position would have emerged as alarming.
- On the basis of the present resource assessment, out of the total 1505 watershed, 76 watersheds are categorised as overexploited i.e., the groundwater development is more than 100 per cent of the recharge and the water table during either post or pre monsoon interval or both shows a declining trend. 20 watersheds are categorised as critical where groundwater development is more than 90 per cent of the recharge and where water table, either post or pre monsoon interval or both, shows significant declining trend and 163 watersheds are categorised as semi-critical where groundwater development is between 70 and 90 per cent of the recharge and where water table in both pre or post monsoon interval, shows declining trend.
- Out of the total tahsils 7 are categorized as over-exploited, one tahsil is categorized as critical and 23 tahsils are categorized as semi-critical. Out of the 23 tahsils, in 11 tahsils the exploitation is more than 95 per cent i.e., they are in the verge of transformation into the overexploited category. The areas which have emerged as overexploited, critical or semi-critical are the areas in which we have the lowest rainfall, highest percentage of water guzzling commercial crops and progressive deterioration of the groundwater and soil quality.
It is recommended that assessment of hydrologic budget of the area may be carried out periodically giving the due considerations to the prevailing groundwater development scenario and constituent modification in the recharge-discharge regime.
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