Palaeochannels — remnants of once active rivers/streams or paths abandoned by rivers when they change their course either due to movement of tectonic plates or severe floods — can be solutions to country's increasing water crisis.
A Government expert committee on “Palaeochannels of North-West India: Review and Assessment”, headed by geologist Prof KS Valdiya, said there are numerous palaeochannels in the country with potential to store/offer billion cubic metres of fresh water. The committee was set up by the Ministry of Water Resources.
Of the States where the panel conducted the study, Haryana, southern Punjab, Rajasthan and Gujarat alone have palaeochannels running more than 2200 km and their water quality is generally good, the experts said. Some of the palaeochannels lie buried under younger sediments.
“In the context of prevalent dryness in larger swathes of our country and the growing need for water for a variety of purposes, the palaeochannels hold good promise as rich repositories of groundwater. They have proved to be a dependable source of supply in many parts of the world,” the committee said in the report.
The panel found that some of the palaeochannels are “dry, while some have water”. More importantly, almost all of them can be artificially recharged and replenished with water, it said. “The palaeochannels promising to hold substantial amount of water thus act as storage reservoirs augmenting groundwater resources,” they said.
According to a senior Central Ground Water Board (CGWB) official, some of the palaeochannels studied by the committee are 50 metre to a few kilometres wide and 10 ft to 30 ft deep.
“So you can imagine the quantum of water that can be sourced from these palaeochannels. Maybe billions cubic metre of freshwater from across the country,” says the report. The committee has recommended that the Government legislate a law to regulate extraction of water from palaeochannels in view of low rainfall in dry stretches and reckless exploitation of freshwater for irrigation and other purposes.
The panel suggested to develop systematic database of all surface maps of palaeochannels and sub-surface stratigraphic data including geophysical surveys, borehole data, chemical quality and isotopic composition of groundwater in and around palaeochannel. It also proposed launching of a mission to facilitate accurate estimation of groundwater reserves.