Copious pre-monsoon showers improve groundwater level in many taluks in Karnataka

Hubballi: The copious pre-monsoon showers that lashed the state between March and May have increased the groundwater table in 138 taluks by at least two meters below ground level (mbgl) compared to last May.

However, there are also 19 taluks which witnessed a fall in groundwater table level by 0-4 mbgl.

Three months ago, almost all observatory wells in the State had shown depleted groundwater and experts say that the rise in the current water levels can be attributed to the substantial rain and high-concentrated spells across the State.

Between March 1 and May 31, the state has received nearly 171 mm of excess rainfall. The normal pre-monsoon showers the State usually receives is 115 mm of rainfall. However, this year it is 286mm, a huge increase of nearly 149 per cent.

The three coastal districts have received 707 mm of excess rainfall in these three months whereas the four Malnad districts have received 443 mm of above-normal rainfall. While 13 North Interior Karnataka districts have received 189 mm of excess rainfall and the 11 south interior districts of the State have received 229 mm of rainfall.

According to the data compiled by the Department of Minor Irrigation and Ground Water Development, nearly 85 taluks, the majority of them in Central Karnataka, parts of Kittur Karnataka and a portion of Bidar and Kalaburagi have witnessed a rise in groundwater level in excess of 4 meters below ground level (mbgl).

Nearly 53 taluks saw a rise in groundwater levels in the range of 2 and 4 mbgl. 73 taluks, predominantly in Kalyana and Kittur Karnataka region, have witnessed a rise in groundwater table by 0-2 mbgl.

Taluks in Kolar, Chikkabalapur, Bengaluru Rural and Ramanagara have witnessed a sharp fall of over 4 mbgl this May, says the the department’s analysis. A total of 19 taluks, the majority of them in South Karnataka have recorded a fall in groundwater level by zero to four mbgl.

“This is, however, too early to say that groundwater has increased drastically in the State. Given that last year the State had received above-normal rainfall for a longer period of time, the extraction of groundwater for various purposes might have been minimal. This is showing an improvement in the groundwater table,” says Department of Minor Irrigation and Ground Water Development Secretary BK Pavithra.

The data was compiled after analysing nearly 2,700 observatory wells of the Ground Water Directorate from across Karnataka for pre-monsoon and post-monsoon levels. “A clear picture regarding the increase in groundwater table will be arrived at only after analysing post-monsoon data of this year,” he says.

There are hopes of recharging the groundwater table, which is fast depleting due to various reasons including agriculture and industrial activities. According to a 2021 report from the Karnataka State Natural Disaster Monitoring Centre (KSNDMC), 53 taluks in the State were over-exploiting the groundwater, while 10 taluks are critical and 35 taluks are semi-critical in the extraction of groundwater.

Ground Water Directorate's retired director Ramachandraiah B G says schemes to fill lakes, storage of substantial quantities of water in reservoirs and copious rains last year have helped in improving the groundwater levels.

Karnataka is known to have shallow aquifers, particularly in the southern part of the state, which means storing groundwater is comparatively less. The recharge and depletion of under surface water is faster than compared to other sub-aquifers.

“There is no surprise that the groundwater table in Bengaluru and Kaveri basin has increased sustainably. The recent highly concentrated spell of rain in Bengaluru has almost filled 63 lakes in the city and another 40 are nearly 75% full. This will recharge groundwater,” says S Vishwanath, water conservation expert and urban planner.

He says the rise or fall of groundwater by 4 mbgl will not give a clear picture of the present status of the precious groundwater table.

“The most important aspect is to analyse the total quantity of water available in the aquifers and how we are using it. This water has to be used judiciously and allowed to be recharged,” he says and adds we need to study data of each sub-aquifer for sustainable usage.