Gujarat’s 60 major dams’ capacity, which is calculated at 16,768 million cubic metres, has gone down by about 14.31 per cent as a result of the silt that has gathered in their reservoirs. Revealing this, Gujarat’s environmental NGO Paryavaran Mitra director Mahesh Pandya said, quoting official state government figures, that in the dams’ capacity has gone down by about 2,400 million cubic metres due to siltation.
Talking with media, Pandya, who made public a plea to Prime Minister Narendra Modi, meant to direct Gujarat chief minister Bhupendra Patel to come up with a concrete programme on removing silt, said, if desilting is not carried out, it would “directly impact” Gujarat’s future plans for water conservation, including the ambitious Saurashtra Narmada Avtaran Irrigation (SAUNI), meant to transfer Narmada waters to Saurashtra’s dams, which largely remain empty despite normal monsoon.
Even as praiseing Modi for his emphasis on water conservation by coming with the idea of constructing 75 new dams in as many districts of India for enhancing water conservation, Pandya said, “However desilting is badly affecting dams”, quoting a recent report, which said the Narmada dam is filled with 53 per cent of its capacity but only 39 per cent of the storage “is available in the reservoir for use.” However, he said, there is so far no authentic data on silt gathered in the Narmada dam.
According to Pandya no survey has been carried out on the present silt level in the Narmada dam. Worse, he said, official papers suggest, the silt survey of many large and medium dams of Gujarat was conducted for several years, including 2001, 2009, and 2017-18 and 2021, yet “no action is taken for removal of the silt”.
Narmada dam is filled with 53% its capacity but only 39% of the storage is available in the reservoir for use
According to him, “The reason stated for non-removal of silt was that the desilting process is done in an ad hoc manner and is not scheduled”, hence, no “budget allocation for this has ever been made”. This despite the fact that there is a clear direction on this by the Central Water Commission (CWC) in the report “Assessing and Managing Reservoir Sediment”, published in February 2019.
According to Pandya, the report said, the sediment-induced problems lead to “a number of adverse impacts not only within reservoirs but also in both upstream and downstream areas of river systems with dams”, leading to several “adverse effects” on river systems with reservoirs.
The negative impact of sedimentation mentioned in the report include reduction of storage volume in reservoirs; flood level increase upstream of the reservoir due to changed river slope; less effectiveness of flow/flood management; erosion and shifting of river banks in the downstream areas; coastline erosion due to the lack of fertile silt and nutrient supply; adverse effect on agriculture, fisheries and aquatic plants in the downstream areas.
The letter also seeks to draw Modi’s attention to about high level of illegal sand mining in river beds in Gujarat “leading to desertification and reduced flow of water”, and high level of river pollution in rivers of Gujarat, with the Ministry of Environment, Forest and Climate Change (MoEFCC) declaring 20 of Gujarat’s rivers in the list of “heavily polluted” rivers of India.
According to Pandya, the report said, the sediment-induced problems lead to “a number of adverse impacts not only within reservoirs but also in both upstream and downstream areas of river systems with dams”, leading to several “adverse effects” on river systems with reservoirs.
The negative impact of sedimentation mentioned in the report include reduction of storage volume in reservoirs; flood level increase upstream of the reservoir due to changed river slope; less effectiveness of flow/flood management; erosion and shifting of river banks in the downstream areas; coastline erosion due to the lack of fertile silt and nutrient supply; adverse effect on agriculture, fisheries and aquatic plants in the downstream areas.
The letter also seeks to draw Modi’s attention to about high level of illegal sand mining in river beds in Gujarat “leading to desertification and reduced flow of water”, and high level of river pollution in rivers of Gujarat, with the Ministry of Environment, Forest and Climate Change (MoEFCC) declaring 20 of Gujarat’s rivers in the list of “heavily polluted” rivers of India.
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