Chitale committee constituted to prepare guidelines for desiltation of river Ganga from Bhimgauda (Uttarakhand) to Farakka (West Bengal), submitted its report to Ministry of Water Resources on 19 May 2017.
The committee in its report has recommended a slew of measures like a study of reach wise sediment transport processes along with establishing annual sediment budgets to guide de-silting activities.
It also recommended the preparation of annual reports (Sand registry) describing the previous de-silting/dredging activity and a technical institute may be entrusted to conduct the sediment budget, morphological and flood routeing studies that would examine and confirm the necessity of the de-silting of the reach under consideration.
About the Chitale committee
In July 2016, the Ministry of Water Resources River Development and Ganga Rejuvenation constituted a committee to prepare guidelines for desiltation of river Ganga from Bhimgauda (Uttarakhand) to Farakka (West Bengal). It was asked to establish a difference between desilting and sand mining and also to establish the need for desilting for ecology and e-flow of the river Ganga.
Madhav Chitale (Expert Member, NGRBA) was appointed as Chairman of the committee. Other members of the committee included Secretary, Ministry of Water Resources, River Development & Ganga Rejuvenation, Secretary, Ministry of Environment, Forests & Climate Change and Dr Mukesh Sinha, Director, Central Water and Power Research Station, Pune.
Highlights of the report
• The report says erosion, sediment transport and siltation are very complex phenomena.
• It is impossible to apply a “one-size-fits-all‟ approach to sediment management and control because the issues involved are frequently very regionally-specific.
• Local factors such as topography, river control structures, soil and water conservation measures, tree cover, and riparian land-use or land disturbance (for example agriculture, mining, etc.) can have a large impact on sediment loads in rivers.
• River control structures (such as reservoirs), soil conservation measures and sediment control programmes can cause downstream sediment loads to decrease, while factors such as land disturbance (clearing of vegetation, for example) or agricultural practices can cause increased sediment loads.
• At the same time, indiscriminate de-siltation works may result in more harm to ecology and environment flow. Thus, there is a need to evolve Guidelines, better broad principles, which should be kept in mind while planning and implementing de-silting works.
• According to the report erosion, sediment transport and siltation in large rivers like Ganga are very complex phenomena and their estimation has inherent limitations and uncertainties.
• A reconnaissance of Main River Ganga on Google earth map reveals that different reaches are in a dynamic equilibrium phase.
• Sedimentation is mainly seen downstream of Bhimgauda barrage and near the confluences of tributary rivers with Ganga.
• The discharge congestion, large-scale sediment deposition and its negative effects are mainly seen downstream of the confluence of Ghagra and beyond.
• The river floodplain drastically widens beyond the confluence of Ghagra and is estimated to be around 12 to 15 km.
The committee says though de-siltation works can improve the hydraulic performance of the river and this itself can justify undertaking de-siltation, these have no direct role in improving environment flow in the river. On the other hand, indiscriminate de-silting or sand mining would cause adverse impacts on river e-flow.