1 Vladimir Smakhtin, Luna Bharati, Nilantha Gamage August, 2007 PLANNING WATER TRANSFERS IN KRISHA RIVER BASIN: TECHNICAL FEASIBILITY AND ENVIRONMENTAL IMPACTS

2 APPROACH Analyse NWDA feasibility Reports; identify and closely examine specific technical aspects of transfers using proposed links in and out of the Krishna Basin (IWMI benchmark basin) Detailed focus on Polavaram – Vijayavada link using WEAP – simulating scenarios of water use with and without the Project, with and without EF and with different crop rotations This ensures a combination of a “larger-scale” analysis (hydrological feasibility of transfers in general) with the specific analysis and scenario simulation using detailed data for 1 link Examine environmental impacts of the project on Krishna Delta

3 NRLP LINKS IN AND OUT OF KRISHNA

4 NWDA METHOD USED TO JUSTIFY TRANSFERS Use annual data resolution. Add all known water abstractions back to available observed flows upstream of the link point – to naturalize the flow Develop rainfall –runoff relationships using naturalized flows and rainfall – for the flow observation point Use this relationship to generate naturalized annual flow time series at the (ungauged) link point This TS is used to establish 50% and 75% assured (dependable) annual flows. 75% flow becomes the “surface water available” All projected water demands upstream of the point of potential transfer (e.g. for 2050) are then subtracted from the 75% dependable (assured) flow (yield). If the balance is positive it is a “surplus” basin and a candidate for transfer. Negative – “deficit basin”. This completes justification for a transfer

5 GAPS IN FEASIBILITY REPORTS Limited information is presented Data used are not described in full Methodology of hydrological justification of links could be improved Environmental aspects and impacts are very generally described and are primarily related to submergence of new land and resettlement of population No provision is made for ecological releases from either existing or planned reservoirs

6 THE ISSUE OF DATA RESOLUTION AND ITS IMPACT ON WATER AVAILABILITY ESTIMATES

7 Annual time step data Monthly time step data 75% 75% dependable flow (annual ) 75% dependable flow (monthly)

8 THE ISSUE OF DATA RESOLUTION AND ITS IMPACT ON WATER AVAILABILITY ESTIMATES Estimates of Surface Water Availability (MCM) at 50 and 75% dependability from annual (NWDA) and monthly (IWMI) data resolution for selected link points in and out of Krishna Donor /Receptor point Dependability 50%Dependability 75% Annual dataMonthly annualized Annual dataMonthly annualized Krishna – Alamatti Krishna- Srisalam Godavari- Inchampalli Godavari – Polavaram Krishna VijayavadaNot available11808Not available1964

9 USE OF SPELL ANALYSIS AS A CRUDE ALTERNATIVE An extract from the generated naturalized monthly flow time series at Srisailam. Red line is the planned transfer equivalent to flow volume of 4,783 MCM per month throughout the year. The maximum annual spell (deficit) of around 40,000 MCM may be required to assure the above flow

10 USE OF SPELL ANALYSIS AS A CRUDE ALTERNATIVE Set a feasible limit for maximum cumulative storage upstream of the site (e.g. 20 BCM for Srisalam- slightly higher than the already existing storage here) Do several runs with different flow thresholds until the maximum deficit in the Srisailam time series has dropped to the set maximum The corresponding threshold flow of X MCM per month (or converted to annual volume) becomes the estimate of water available for transfer.

11 USE OF SPELL ANALYSIS AS A CRUDE ALTERNATIVE Srisalam Example

12 USE OF SPELL ANALYSIS AS A CRUDE ALTERNATIVE Polavaram Example

13 ENVIRONMENTAL IMPACTS OF RESERVOIR CONSTRUCTION ON KRISHNA DELTA Reduced flow coupled with continuous storage growth, which is now equal to 36% and 132% of the natural and present day Krishna outlet mean annual flow respectively.

14 ENVIRONMENTAL IMPACTS OF RESERVOIR CONSTRUCTION ON KRISHNA DELTA The time series of sediment loads in Krishna at Agraharam (upstream of most dams) and Vijayavada (downstream of all dams). Most of the sediments are trapped by dams

15 ENVIRONMENTAL IMPACTS OF RESERVOIR CONSTRUCTION ON KRISHNA DELTA Three high resolution images (Landsat) of Krishna Delta have been analysed , 1990 and 2000 Dynamics of six points (outlets of major distributaries) have been examined in detail (figure) Areas of deposition and erosion in the entire delta have been calculated by comparing 1977 image (reference) and 2000 – “current”

16 ENVIRONMENTAL IMPACTS OF RESERVOIR CONSTRUCTION ON KRISHNA DELTA Total net land loss in the delta over 23 years is 1780 ha Rate of loss is 77 ha/year Erosion is 3+ times more than deposition over the study period Areas of erosion dominate coastline (red in Figure) Most likely attributed to reduced sediment delivery during this period

17 CONCLUSIONS All NRLP transfers are justified based on the premise that “natural” annual flow volume which is exceeded 75% of the time (e.g.30 out of 40 years) is available for water utilization. This ignores the variability within a year, which is extremely high in monsoon-driven Indian rivers. Result: much more water may be perceived as ‘available’ at a site of Transfer. All NRLP transfers are further justified based on the States’ maximum plans for irrigation (for 2025 or 2050). This ‘maximizes’ irrigation requirements and serves as THE driver for future water resources development. There is a needs for integrated water resources planning at the basin scale, when all links are modeled simultaneously. It applies to Krishna basin and to other basins earmarked for transfer. It is not possible to properly re-evaluate any plans without having the same starting conditions – the same hydro data. Only very cautious statements can be made here.

18 CONCLUSIONS, cont The alternative assessment of water available for transfer – using spell analysis- is crude, but it suggests that the basins/sites which are thought of as “surplus”, may be effectively in deficit already The demands which are currently considered in feasibility reports include irrigation, hydropower, industry and domestic. Environmental demands must also be explicitly included at the planning stage. This will be a precautionary measure in the absence of other more detailed information at present. Past storage growth in the basin has led to retreat of the Krishna delta, where the rates of erosion exceed the rates of deposition. Even under existing storage delta will likely continue to shrink in the next decades. Environmental releases are necessary. Adding very limited environmental demand into the picture (in the range of 10-15% of the long-term annual flow) makes the transfer sites even more deficit and transfers – even less feasible