Page - 393 - in Book of Full Papers - Symposium Hydro Engineering

REFERENCES [1] NATIONAL OCEANIC AND ATMOSPHERIC ADMINSTRATION (NOAA). https://www.ncdc.noaa.gov/data-access/model-data/model- datasets/climate-forecast-system-version2- cfsv2#CFSv2%20Operational%20Forecasts, 2016. [2] SVOBODA, MARK; FUCHS, BRIAN. Integrated Drought Management Programme (IDMP), Handbook of Drought Indicators and Indices. Drought Mitigation Center Faculty Publications. 117. 2016. [3] GUDMUNDSSON, L.; BREMNES, J. B.; HAUGEN, J. E. & ENGEN- SKAUGEN, T. Technical Note: Down-scaling RCM precipitation to the station scale using statistical transformations - a comparison of methods. Hydrology and Earth System Sciences, 2012, 16, 3383-3390, doi:10.5194/hess-16-3383-2012. SUMMARY The aim of the project is to develop adaptation strategies for dams and reservoirs that take into account shifting precipitation regimes and their resulting discharge and water quality conditions. The emphasis of this study lies on the early recognition of droughts and corresponding reservoir management. The approach will be transferred into a concept for the adaptation of operation rules taking into account competing uses and target conflicts. The approach uses hydro-meteorological indices to identify the need for counter actions at an early stage. Long-term precipitation forecasts from NOAA are bias-corrected for individual ground stations in Germany, for which observed precipitation data is available. The forecasted precipitation values are then used to calculate indices (e.g. Standardized Precipitation Index (SPI)). Conclusions are that the SPI calculated using forecasted data adequately represents the SPI calculated from observed data. In particular, upcoming dry periods can be detected using the forecasts. Using the forecasted SPI to adjust reservoir operation rules based on a certain trigger threshold for the SPI in one case lead to reduced critical low flow conditions. In another case, using operation rules adjusted to respond to a certain SPI threshold resulted in fewer occurrences of reservoir water levels below a critical level. These case studies also showed that the SPI aggregation period and the SPI threshold value for triggering adjustments to the operating rules have to be determined individually for each site. Further steps in the study will involve testing different indices and establishing generalized approaches for integrating index forecasts into reservoir operation. 393