MAHARASHTRA is one of the first three states in the country to get the proposed 2016 Groundwater Assessment methodology ratified by the Central Ground Water Board (CGWB). With this, hydrologists here would be able to provide a better picture of the groundwater situation, that in turn will help in improved planning of contingency measures during water crisis. After every three years, the CGWB revises assessment techniques and asks the states to upgrade some of the existing methods.
Every state designs and modifies its existing methodology, based on the results obtained from previous assessment reports, overall recharge trend and water conservation modes adopted in the areas, among other factors. “With the new assessment scheme, government agencies involved in water management will be able to undertake focused planning based on real-time availability of groundwater. This will be crucial for areas where the reserves are sparse,” Shekhar Gaikwad, director, Groundwater Survey and Development Agency (GSDA) told The Indian Express. So far, the assessment proposals of Telangana and Tamil Nadu have been considered for final rounds by the CGWB.
Watersheds, or areas that have in place some kind of medium (natural or artificial) for enabling water seepage – like canals, tanks, ponds or other water conservation structures — are considered. Whereas, hilly and dry areas are ruled out from the assessment. As per the proposed assessment technique, crucial groundwater data from all areas, whether or not under any water conservation regime, would be considered for the overall estimation of the natural water reserves. Earlier, this data would be collated as one unit, thereby not giving the actual picture of the groundwater scenario whenever there are areas with partial recharge trend.
In case of Maharashtra, the natural geology comprising hard basalt rock limits seepage of groundwater in majority of its area. It not only poses a major challenge in western and central regions of the state but also leads to deeper digging of wells to extract natural reserves. Moreover, the dependence share on surface water for drinking, irrigation and other purposes becomes much larger.
The threshold values to tag a particular watershed into critical, semi-critical, safe and poor categories stands revised. According to the 2016 assessment plan, watersheds with recharge rate of up to 70 per cent would be considered as safe. If the recharge lacks anywhere between 70 and 90 per cent, it would be termed as semi-critical. Recharge rate lacking anywhere between 90 and 100 per cent would be considered critical and anything over 100 per cent stands as over exploited watershed. Until now, the recharge rate threshold for safe category was considered to be 75 per cent.
As per the 2013 assessment report, four watersheds were termed critical and 111 were termed semi-critical. Most of these watershed were located in Aurangabad, Nashik and neighbouring areas of north Maharashtra and Marathwada, said an in-charge, who is a member of the 2016 assessment team. Poor quality reserves were reported from Amravati (3) and Akola (1) during the last assessment.