As dry summer months loom, Mhadei row over drinking water

PANAJI: With Karnataka’s continued blockage of the Kalsa tributary, which is likely to further deplete the

water

flow already reduced to a trickle, the

Mhadei

water row may well create more tensions over drinking water as the

dry

months of

summer

loom.

In mid-January, water resources minister Vinod Palyekar inspected the site of the Kalsa diversion canal at Kankumbi. Then, this past Sunday, a team of Goan legislators led by Speaker Pramod Sawant visited the area. But even after Goa’s protests, Karnataka’s actions have been found to be an eyewash, as only seepage is leaking into the stream flowing towards Sattari.

“The blockage of the Kalsa tributary is likely to affect drinking water schemes, especially in Ganjem as the water is pumped from here into Khandepar river to feed the Opa plant,” said P J Kamat, assistant chief engineer, water resources department (WRD).

Goa has argued before the Mhadei water disputes tribunal (MWDT) that the Mhadei river basin, which covers 42% of the state’s geographical area, is a deficient basin. The state has also pointed out that the percolation to ground water aquifer actually maintains the river flow, called base flow, during non-monsoon months.

A study by Manoj Ibrampurkar, an assistant professor of hydrogeology in a city college, has estimated that 638 million cubic metres (MCM), or 19% of the total annual discharge measured at the Ganjem river-gauging station, is base flow component.

“The base flow component sustains till January, indicating higher groundwater levels during this period. However, it diminishes rapidly then onwards during the summer season,” Ibrampurkar’s report states.

The Mhadei river originates in Degao, Karnataka, and is enriched by a maze of tributaries and streams. As a monsoon-fed river with many picturesque waterfalls and green valleys en route, it has no snow melt support. The flow after the monsoon season is as low as 1.6% of the monsoon flow.

“The diversion of water outside the Mhadei basin will further reduce this base flow and severely and adversely impact the environment and drinking water supply to the people living along the river banks,” the state has explained in its submission to MWDT.

It is also considered vital to determine the water requirement for ecological sustenance of the river valley with endemic species in the global biodiversity hotspot of the Sahyadris. Global warming, sea level increase, and the rise in salinity influx towards hinterland are factors that can affect water quality.

Ibrampurkar has stated that the fresh water-sea water interface at Ganjem may not greatly be affected by reduction in the flow volume and velocity due to Karnataka’s projects. “However, a minor increase in the salinity of the mixing zone cannot be ruled out,” he said.

The quality of water in a watershed depends on the interactions of rainwater with all the rock types in the basin. “The retention of the flows in the upstream of the present watershed (by Karnataka) may lead to some changes in the resultant water quality in the downstream,” the hydrogeologist concluded.