Lok Sabha Question No. 3368 (UNSTARRED), answered on 2025-03-20
Subject: Silt Accumulation in Rivers and Dams
Ministry: JAL SHAKTI
Asked by: Smt. Bharti Pardhi, Shri Bajrang Manohar Sonwane, Shri Shrirang Appa Chandu Barne, Shri Kanwar Singh Tanwar

## GOVERNMENT OF INDIA MINISTRY OF JAL SHAKTI

## DEPARTMENT OF WATER RESOURCES, RIVER DEVELOPMENT & GANGA REJUVENATION

## LOK SABHA UNSTARRED QUESTION NO. 3368

ANSWERED ON 20.03.2025

## SILT ACCUMULATION IN RIVERS AND DAMS

3368.

SHRI SHRIRANG APPA CHANDU BARNE

SHRI BAJRANG MANOHAR SONWANE

SMT. BHARTI PARDHI

SHRI KANWAR SINGH TANWAR

Will the Minister of JAL SHAKTI be pleased to state:

(a)  whether  a  huge  quantum  of  silt  is  accumulated  in  the  rivers  and  dams  across  the  country  including Madhya Pradesh which contributes to increase flood risks in the rivers and decreasing the water-holding capacity of the dams/reservoirs;

(b) if so, the extent to which the huge amount of silt deposited in rivers increases the risk of floods;

(c) whether the Government has conducted any study to find out the contribution and impact of excess silt on various rivers of the country, particularly on Ganga river, if so, the details thereof, river-wise;

(d) the steps taken/being taken by the Government for removing the accumulated silt from the rivers and dams/reservoirs along with the manner in which these steps have been effective in removing silt;

(e) the details of the economic consequences of silt buildup in navigable waterways; and

(f)  the  action  taken/being  taken  by  the  Government  for  the  effective  implementation  of  regulations  and policies in controlling silt pollution?

## ANSWER

## THE MINISTER OF STATE FOR JAL SHAKTI

## ( SHRI RAJ BHUSHAN CHOUDHARY )

(a) to (f) Erosion, movement and deposition of sediment in a river are natural regulating functions of a river. Rivers tend to maintain a balance between the silt load carried and silt load deposited, maintaining a river regime. Dredging/desilting of rivers is not considered a technically viable solution for flood control as it  can  marginally  minimize  the  magnitude  of  floods  and  is  effective  only  for  a  short  period.  Selective dredging  in  specific  reaches  such  as  tidal  rivers,  confluence  points  with  narrow  constrictions,  etc. sometimes  may  have  to  be  undertaken  based  upon  local  site  conditions;  however,  the  same  should  be backed by proper scientific study.

Sedimentation  is  a  natural  phenomenon  which  causes  accumulation  of  Silt  in  Reservoirs  and reduces the storage capacity of the  reservoirs.  Central  Water  Commission  (CWC)  has  prepared

Compendium  on  Sedimentation  of  Reservoirs  in  2024  on  the  basis  of  data  of  548  reservoirs.  The compendium with  2  volumes  is  available  on  CWC  website  at  https://cwc.gov.in/sites/default/files/vol-icompendium-2024.pdf and https://cwc.gov.in/sites/default/files/vol-ii-compendium-2024.pdf. Of these 548 reservoirs, data of sedimentation studies of 21 reservoirs of Madhya Pradesh and 35 reservoirs of IndoGangetic plains is available in Volume II of the compendium.

National Mission for Clean Ganga under the Department of Water Resources, River Development and Ganga Rejuvenation, Ministry of Jal Shakti has prepared guidelines in 2017 for de-siltation of works on river Ganga from Bhimgauda( Uttarakhand) to Farakka (West Bengal).

Government  of India has implemented the World Bank funded Dam  Rehabilitation and Improvement Project (DRIP), Phase-I, during 2012-2021. The scheme was having need-based provisions of  de-silting  of  reservoirs  of  few  selected  reservoirs.  The  sedimentation  management  were  studied  for Kundah Palam dam, Papanasam Weir, Pillur dam (Tamil Nadu) and Maneri Bhali Stage-I (Uttarakhand). Also,  catchment  area  treatment  for  Kundah  Palam  Catchment  was  carried  out.  The  Government  of Uttarakhand has carried out small scale de-siltation of Asan Barrage, wherein quantity of silt removed was 78,000 cubic meters.

The  DRIP  Phase  II  and  Phase  III  also  have  need  based  provision  for  sediment  management interventions including de-siltation of reservoirs, catchment area treatment, among others. This Scheme has 19 States on board, budget outlay of Rs. 10,211 Crore and rehabilitation provision for 736 dams. The new Scheme  envisages  Catchment  Area  Treatment  of  four  reservoirs  of  Tamil  Nadu  namely Vaigai, Nanganjiyar,  Parappalaru,  Kodaganar  dam;  2  reservoirs  of  Bhakra  Beas  Management  Board  (BBMB) namely  Bhakra  Dam  and  Pong  Dam,  and  de-silitation  of  two  dams  of  Tamil  Nadu  Generation  and Distribution Corporation Limited namely Papanasam and Kundah Palam.

CWC has also published 'Handbook for Assessing and Managing Reservoir Sedimentation' in year 2019. Also, other Guidelines titled 'Operational Procedures for Assessing and Managing Environmental Impacts in  Existing  Dam  Projects'  has  been  published  by  CWC  in  year  2020.   These  Guidelines  cover various rehabilitation activities, including de-silting of reservoirs and give the way forward to address the environment and social safeguards in order to facilitate dam owners.

Under National Hydrology Project (NHP), comprehensive bathymetric surveys have been conducted  to  address  the  critical  issue  of  sedimentation  in  reservoirs,  which  threatens  water  security, hydropower  generation,  and  flood  management.  The  project  analyzed  462  reservoirs  across  22  states, accounting for a gross storage capacity of 156.815 BCM. As of June 2024, surveys for 334 reservoirs (72% of the total) have been completed, with findings revealing significant sedimentation impacts.

A National Framework for Sediment Management (NFSM) has been notified in January, 2023 by Department of Water Resources, River Development and Ganga Rejuvenation, Ministry of Jal Shakti. It emphasis on reducing silt  generation  rather  than  silt  removal  and  promotes  technological  innovations  &

best  practices.  Further,  it will  provide  overall  guidance  to  States/UTs  on  various  aspects  of  sediment management,  handling  issues  of  sediment  management  in  integrated  &  scientific  manner  and  use  of different approaches of sediment management in a river basin.  The same is available at https://jalshaktidowr.gov.in/document/policy-on-sediment-management/

Siltation  affects  navigability  of  the  channel.  Inland  Waterways  Authority  of  India  (IWAI)  under Ministry  of  Ports,  Shipping  &  Waterways  is  mandated  with  development  and  maintenance  of  national waterways for the purposes of shipping and navigation. IWAI carries out river training and maintenance dredging in the national waterways for maintaining a depth of 2 to 3 m with a bottom width of 35 to 45 m for safe shipping and navigation. The silt deposits in navigation channels affects the cost of river training and maintenance dredging in the navigation channels.

The  Ministry  of  Environment,  Forest  and  Climate  Change  has  issued  Sustainable  Sand  Mining Management Guidelines 2016. The main objective of the Guidelines is to ensure sustainable sand mining and environment friendly management practices in order to restore and maintain ecology of river and other sand sources.

*****