The groundwater table in several districts had shown considerable improvement, thanks to the bountiful rains that had lashed the State in August. Kancheepuram, Chennai and Theni disticts had shown remarkable increase in the water level compared to last month.
While half of the districts had recorded a rise in the water table , Kancheepuram topped the list with a jump in the water table by 5.14 metres compared to July, according to the State Ground and Surface Water Resources Data Centre, Water Resources Department. The centre had compiled the groundwater data of all districts, except Chennai. Chennai Metrowater remained the monitoring authority for city’s sources through its hydro-geology wing.
Excess rainfall
Kancheepuram was one district that had registered excess rainfallthis season. Tamil Nadu had recorded a rainfall of 305.3 mm against 217 mm of normal rainfall for the season so far. Only a few districts like Kanyakumari, Nilgiris and Karaikal had received deficit rainfall during the South west monsoon.
Officials of WRD said that the water level in some districts, which had shown a rise in one month, still remained much below than August last year. For instance, Dindigul district might have had a rise in water table in August compared to the previous month. But, the water table remained at 12.23 metres below ground level, which was nearly two metres lower than last year. It was the same case with Kancheepuram district too.
Evening showers that had almost become typical in Chennai during August had influenced the groundwater resources. According to data from Metrowater, the average water table had gone up by nearly 1 metre in August than the previous month this year in the city. But, it still had not matched the water level that stood at 3.40 metre in August last year.
A welcome relief
Groundwater experts said that the thunder showers in August were a welcome relief as the rainfall had saved the water table from plummeting further. With many water bodies nearly dry and municipal supply running low in several districts, people had turned towards groundwater resources to meet their needs.
The increase or dip in the water table was not only related to the rainfall received but also to the extent of extraction of groundwater. For instance, the seasonal rainfall in Tiruvallur district had exceeded its usual quota by 26 %. But, the water table had dipped by 0.50 metres.
Officials of Metrowater said that August rainfall over Chennai and neighbouring districts might not have filled the reservoirs. The ground water level was lower than August last year because Metrowater had cut down supply to 420-450 million litres now for want of resources. But, it had boosted the water table just enough to cater to residents’ needs.