One rain, two lakes & 2.1 million litres: New tech reveals Bengaluru's filling waterbodies

Bengaluru: A single spell of rain on Saturday evening brought 2.1 million litres of water to two lakes in the southern outskirts of Bengaluru. 

This was found by SayTrees, a Bengaluru-based NGO, which has installed solar-powered radar-based sensors in Handenahalli and Sollepura lakes to measure changes in water levels. 

According to a post on X by the founder Kapil Sharma, two lakes collected about two million litres of water in a single day of rain on Saturday. "Waiting for monsoon as the NGO is getting 10 lakes in Bengaluru, two in Hyderabad and 15 in Maharashtra ready to receive rain water," he wrote. 

Lt Cdr Deokant Payasi (retired), CEO of SayTrees, said that four such sensors had been imported from the Netherlands from a firm called OBSCAPE because no company in India offered solar-powered radar-based sensors. 

"A sensor is on a pole fixed in the middle of the lake or in an area where the water levels can be clearly monitored at any given point of time and help us understand the water flow is in the lake. Suppose the water level has a steep decline, then we can identify that there is a leak somewhere that we must plug," he told DH. 

While Handenahalli Lake saw the water level increase by 0.02 metre, Sollepura Lake gained a 0.01-metre height from the existing level (calculated from the base of the lake) after the rains on Saturday. 

Over the past year, the NGO has worked to restore these two lakes by clearing the inlets and outlets, desilting, fixing the bund and fencing the lakes to deter garbage and construction debris dumping. The sensors also help assess this work's impact, he added. 

"A single day's rainfall filling these two lakes up by 2.1 million litres of water goes to show that if we catch the rainfall properly, we will have more than enough water to recharge our borewells," said Payasi.