1,000 dams on Ganga basin obstructing tributaries: Study

There are at least a thousand dams on the Ganga basin obstructing the flows of its various tributaries and adversely affecting the overall health of the river system, according to a recent assessment by researchers and experts from multiple organisations.

“Rejuvenating Ganga — a citizen’s report” released during ongoing India Rivers Week, has put together an analysis of why flows in most rivers of the Ganga basin are dwindling, and recommended that the Centre make environmental flows mandatory for the entire basin and not just the main stem of the river.

The Natural Heritage Division of the Indian National Trust for Art and Cultural Heritage (INTACH) has mapped the dams, barrages and hydroelectric projects based on data from Water Resources Information System of the Central Water Commission, the Uttarakhand Renewable Energy Development Agency, and the Uttarakhand Jal Vidyut Nigam.

“We have found more than a thousand dams on the Ganga basin. The main reason for declining flows in our rivers is these dams, according to our assessment. Other reasons are ruthless sand and boulder mining, indiscriminate extraction of groundwater and loss of flood plains,” said Manoj Mishra, convener of the Yamuna Jiye Abhiyan and river expert who has co-authored the report.

The report, which is the summary of a book that organisations such as INTACH, Worldwide Fund for Nature and the Dehradun-based Peoples’ Science Institute are putting together, says certain stretches of the rivers linked to the Ganga -- such as Betwa, Chambal, lower Yamuna, Sone, Kiul, Damodar and Ganga Sagar -- have recorded more than 50% decline in annual and seasonal flow over a 31-year period between 1975 and 2005.

Experts gathered at the Rivers Week proceedings in New Delhi said it was time that the Namami Gange Program of the Centre define the environmental flows (e-flow is a regime of flow in a river that mimics the natural pattern; tt refers to the quality, quantity and timing of water flows required to maintain the components, functions, processes and resilience of aquatic ecosystems that provide goods and services to people) for all tributaries in the Ganga basin.

“This is also the mandate given to the National Mission for Clean Ganga (NMCG) by the Ganga Authorities Order, 2016,” the report states. “Not all dams impact river flow. But diversions where water is withdrawn for other purposes like irrigation, flow is impacted. Some dams like the Tehri dam in Uttarakhand have helped maintain a flow in the lean season. Whether we need a moratorium on further diversions and dams on the Ganga basin should be decided through negotiations between stakeholders and the government,” said Prof Vinod Tare, a water expert from IIT, Kanpur.

NMCG, on October 10 last year, published a notification specifying the minimum environmental flow for the Ganga main stem in the dry, lean and high flow seasons. The notification was to complied with by all hydroelectric projects and large dams by 2021. NMCG has now advanced this deadline to December 15, 2019.

“Ganga main stem has only five dams or barrages including Farrakka. These must be small dams on rivulets in the basin. We don’t have the total count of dams or barrages on Ganga basin,” said Rajeev Ranjan, director general of NMCG, when asked about the report.