Lok Sabha Question No. 313 (STARRED), answered on 2023-08-10
Subject: Water Loss in Reservoirs
Ministry: JAL SHAKTI
Asked by: Komati Reddy Venkat Reddy, Manne Srinivas Reddy

## GOVERNMENT OF INDIA MINISTRY OF JAL SHAKTI

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

## LOK SABHA

## STARRED QUESTION NO. *313

ANSWERED ON 10.08.2023

## WATER LOSS IN RESERVOIRS

*313 SHRI KOMATI REDDY VENKAT REDDY SHRI MANNE SRINIVAS REDDY Will the Minister of JAL SHAKTI be pleased to state:

- (a)  the  details  of  the  water  losses  in  the  reservoirs  since  1947  onwards  till  date,  State-wise  and  the reasons therefor;
- (b)  whether  the  Government  is  taking  various  measures  to  reduce  water  losses  in  reservoirs  such  as reducing the surface area of the reservoir, lining the bottom and sides of the reservoir with invincible materials  and  adopting  water  management  methods  that  reduce  the  operating  spillage  and  such  other measures; and
- (c) if so, the details thereof along with the details of the outcome and funds spent for the purpose?

## ANSWER

## THE MINISTER OF JAL SHAKTI

(SHRI GAJENDRA SINGH SHEKHAWAT)

(a) to (c) : A statement is laid on the Table of the House.

## STATEMENT REFERRED TO IN REPLY TO PARTS (a) TO (c) OF LOK SABHA STARRED QUESTION NO. *313 TO BE ANSWERED ON 10.08.2023 REGARDING 'WATER LOSS IN RESERVOIRS'.

(a)  to  (c) Water  Resources  Projects  are  planned,  funded,  executed  and  maintained  by  the  State Governments themselves as per their own resources and priority. In order to supplement their  efforts, Government  of  India  provides  technical  and  financial  assistance  to  State  Governments  to  encourage sustainable  development  and  efficient  management  of  water  resources  through  various  schemes  and programmes.

As such, information related to water losses in various reservoirs of the country is available with the concerned dam owners.  Water in a reservoir may  be lost  by  surface  evaporation,  by  seepage  into  the surrounding soil or rocks and by seepage through dam foundations.

Evaporation  from  reservoir  surface  is  a  well  known  phenomenon.  As  per  the  Central  Water Commission (CWC) report on 'Reassessment of Water Availability in India using Space Inputs -2019' average annual reservoir evaporation (30  years average) is 27,510 Million Cubic Meters (MCM). The basin  wise  average  evaporation  is  given  at Annexure .  As  per  the  report  on  'Evaporation  Control  in Reservoirs'  2006  published  by  the  CWC,  various  factors  affecting  the  evaporation  from  reservoir  are surface  area,  area  exposed  to  the  atmosphere,  temperature,  vapour  pressure  difference,  wind  effect, atmospheric pressure and quality of water.

The common methods adopted for reducing evaporation from reservoirs are wind breakers, covering the water surface, reduction of exposed water surface, underground storage of water, integrated operation of reservoirs and treatment with chemical popularly called Water Evapo-Retardants.

Government of India is implementing the externally funded Dam Rehabilitation and Improvement Project (DRIP). During the DRIP Phase-I programme implemented during 2012 to 2021, 223 dams were rehabilitated  to  improve  various  safety  concerns  such  as  structural  safety,  operational  safety  and hydrological  safety  of  the  dams.  To  this  effect,  various  remedial  measures  have  been  undertaken, specifically for addressing seepage issues at given dams. Grouting works carried out at 42 dams, joint treatment works carried out at 13 dams, application of geo- membrane done at 2 dams, upstream face treatment done at 37 dams. These measures have been effective and helped in addressing seepage issues, thereby reducing the water losses from the reservoirs.

After completion of DRIP Phase-I programme, Govt. of India is now implementing the DRIP PhaseII & III Scheme. The Scheme envisages the rehabilitation of 736 dams located in 19 States at cost of Rs. 10,211 crores. Under DRIP Phase-II & III Scheme, seepage reduction measures would be undertaken at few dams on need basis based on safety concerns of the given dam. The physical interventions such as upstream  face  treatment,  joint  treatment,  grouting  etc  would  be  implemented  to  address  the  seepage issues to the possible extent, so as to contribute in reducing the loss of water from the given reservoirs.

## ANNEXURE  REFERRED  TO  IN  REPLY  TO  PART  (a)  to  (c)  OF  LOK  SABHA  STARRED QUESTION NO. *313 TO BE ANSWERED ON 10.08.2023 'WATER LOSS IN RESERVOIRS'

Basin Wise Average Annual Reservoir Evaporation (30 Years Average)

| Sl. No.   | BASIN                                                    | Average Annual Reservoir Evaporation(MCM)   |
|-----------|----------------------------------------------------------|---------------------------------------------|
| 1         | GODAVARI BASIN                                           | 4,410                                       |
| 2         | KRISHNA BASIN                                            | 2,110                                       |
| 3         | CAUVERY BASIN                                            | 650                                         |
| 4         | SUBERNAREKHA BASIN                                       | 540                                         |
| 5         | BRAHMANI-BAITARANI BASIN                                 | 930                                         |
| 6         | MAHANADI BASIN                                           | 1,410                                       |
| 7         | PENNAR BASIN                                             | 140                                         |
| 8         | EFR BETWEEN MAHANADIAND PENNAR BASIN                     | 1,620                                       |
| 9         | EFR BETWEEN PENNAR AND KANYAKUMARI BASIN                 | 370                                         |
| 10        | MINOR RIVERS DRAINING INTO MYANMAR(BURMA) AND BANGLADESH | 400                                         |
| 11        | INDUS (HARIKE SUB-BASIN ONLY)                            | 480                                         |
| 12        | UPPER GANGA SUB-BASIN                                    | 760                                         |
| 13        | LOWER GANGA SUB-BASIN                                    | 6,030                                       |
| 14        | YAMUNA SUB-BASIN                                         | 1,870                                       |
| 15        | BRAHMAPUTRA BASIN                                        | 0                                           |
| 16        | BARAK &OTHERS BASIN                                      | 810                                         |
| 17        | MAHI BASIN                                               | 750                                         |
| 18        | SABARMATI BASIN                                          | 410                                         |
| 19        | NARMADA BASIN                                            | 480                                         |
| 20        | TAPI BASIN (UPTO GHALA)                                  | 780                                         |
| 21        | WFR FROM TAPI TO TADRI                                   | 1,290                                       |
| 22        | WFR FROM TADRI TO KANYAKUMARI BASIN                      | 1,270                                       |
| 23        | WFR OF KUTCH AND SAURASHTRA INCLUDING LUNI BASIN         | NA                                          |
| Total     |                                                          | 27,510MCM                                   |

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