Experts believe that accumulation of debris from large-scale construction and mining on riverbeds is one of the key reasons why rivers in Uttarakhand are changing their course.
Prof. Shekhar Pathak, historian and expert on the Himalayan region, pointed out that the construction boom had fuelled illegal mining of sand and boulders from riverbeds across the entire Himalayan belt. This large-scale extraction had changed the slope of the riverbed, forcing the river to change its course.
Prof. Pathak cited the example of Alaknanda river changing its course abruptly in June which saw it flowing through the Srinagar city. The huge quantity of silt and boulders that it was carrying saw it banks being raised by 40 feet.
The environment ministry and the Prime Minister’s Office had been repeatedly warned against muck being allowed to accumulate along the river banks often because of the construction of huge tunnels to build the run-of-the-river dams, thereby, forcing the river to flow at higher and higher levels.
“Each of these projects generates millions of tonnes of muck. Scientists have calculated that one hydro project requires several lakhs truckloads to remove this muck. The cheapest way out is to dump this waste material into a river,” Prof. Pathak added.
This was confirmed by geologist Naveen Junyal with the Physical Research Laboratory, Ahmedabad, who pointed out that the massive 1893 and the 1970 floods in the Alaknanda did not record such high levels. “The June 2013 floods are the highest levels that the Alaknanda has recorded so far in the 1,000 years of recorded history of floods in this region,” pointed out Dr Junyal.
The situation remains the same with the other rivers, including the Mandakini, the Bhagirathi and the Dhauli Ganga.
The inability of the government to restrict construction within 200 metres of the riverbed has also exacerbated the problem.
Scores of buildings have come up on loose beds of gravel which went down live nine pins when the floods came. The department of science and technology had entrusted Dr Junyal and a team of scientists to diagnose the reasons for this catastrophe.