Trust Fund for Environmentally & Socially Sustainable Development Public Disclosure Authorized Water & Climate Adaptation Plan for the Sava River Basin Public Disclosure Authorized Public Disclosure Authorized Public Disclosure Authorized ANNEX 1 - Development of the Hydrologic Model for the Sava River Basin April 2015 © 2015 The World Bank 1818 H Street NW Washington DC 20433 Telephone: 202-473-1000 Internet: www.worldbank.org Water & Climate Adaptation Plan for the Sava River Basin ANNEX 1 - Development of the Hydrologic Model for the Sava River Basin August 2015 ACKNOWLEDGMENTS This work was made possible by the financial contribution of the World Bank’s Water Partnership Program (WPP) - a multi-donor trust fund that promotes water security for inclusive green growth (wa- ter.worldbank.org/water/wpp) and the Trust Fund for Environmentally & Socially Sustainable Development (TFESSD). DISCLAIMER This work is a product of The World Bank with external contributions. 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Project No. A040710 Document no. 1 Version 10 Date of issue August 2015 Prepared JAP/DAH Checked DAH/RSS Approved DAM Page i Water & Climate Adaptation Plan for the Sava River Basin Development of the Hydrologic Model for the Sava River Basin Table of Contents Page No 1 INTRODUCTION ................................................................................................................................... 1 2 PRELIMINARY CONSIDERATIONS FOR MODEL DEVELOPMENT .................................................. 3 2.1 Selection of the model ........................................................................................................................... 3 2.2 Data collection ....................................................................................................................................... 4 2.3 Selection of the calibration and verification periods .............................................................................. 6 2.4 Record extension ................................................................................................................................... 6 3 MODEL SETUP ..................................................................................................................................... 7 3.1 Basin subdivision ................................................................................................................................... 7 3.2 HEC-HMS setup .................................................................................................................................. 10 4 MODEL CALIBRATION AND VERIFICATION .................................................................................... 13 4.1 Control hydrologic stations .................................................................................................................. 13 4.2 Model performance criteria .................................................................................................................. 14 4.3 Calibration and verification results ....................................................................................................... 15 4.4 Verification of simulations with the extended record of input data ...................................................... 19 5 MODEL APPLICATION WITH FUTURE CLIMATE SCENARIOS ...................................................... 21 5.1 Methodology ........................................................................................................................................ 21 5.2 Climate scenarios as the input to the hydrologic model ...................................................................... 22 5.3 Hydrologic simulation with baseline climate scenarios ........................................................................ 26 5.4 Hydrologic simulations with future climate scenarios .......................................................................... 28 6 REMARKS ON UNCERTAINTY OF THE RESULTS .......................................................................... 33 7 REFERENCES .................................................................................................................................... 35 APPENDIX A: Inventory of collected data .......................................................................................................... 37 APPENDIX B: Elements in the Sava hydrologic model ...................................................................................... 46 APPENDIX C: Simulated vs. observed monthly flow hydrographs for the calibration period 1979-1984 .......... 50 APPENDIX D: Simulated vs. observed monthly flow hydrographs for the verification period 1969-1974 ......... 59 APPENDIX E: Simulated vs. observed seasonal stremflow distribution for the calibration period 1979-1984 .. 68 APPENDIX F: Simulated vs. observed seasonal streamflow distribution for the verification period 1979-1984 72 APPENDIX G: Simulated vs. observed seasonal streamflow distribution for the extended record 1961-1990 . 76 APPENDIX H: Seasonal streamflow distribution simulated with input from climate models for 1961-1990 ...... 81 APPENDIX I: Change in mean seasonal and annual streamflows in the future compared to 1961-1990 – complete results ................................................................................................................................... 85 APPENDIX J: Change in mean seasonal and annual streamflows in the future compared to 1961-1990 – ensemble median values ..................................................................................................................... 91 List of Tables Page No. TABLE 1: MAJOR SUB‐BASINS FOR THE SAVA HYDROLOGIC MODEL WITH CONTRIBUTING AREAS .................................................................. 8 TABLE 2: LIST OF SUB‐BASINS IN THE SAVA HYDROLOGIC MODEL .......................................................................................................... 9 TABLE 3: GENERAL PERFORMANCE RATINGS FOR NSE AND PBIAS FOR A MONTHLY TIME STEP (FROM MORIASI ET AL., 2007) ...................... 15 TABLE 4: THE LIST OF CLIMATE SCENARIOS RESULTING FROM FIVE GCM/RCM COMBINATIONS ............................................................... 22 TABLE 5: CHANGE IN ENSEMBLE MEDIAN VALUES OF MEAN SEASONAL (DJF, MAM, JJA, SON) AND ANNUAL (ANN) RUNOFF, AVERAGED OVER 50 LOCATIONS IN THE SAVA BASIN, AND NUMBER OF LOCATIONS EXHIBITING INCREASED OR DECREASED RUNOFF ............................... 29 Page ii Water & Climate Adaptation Plan for the Sava River Basin Development of the Hydrologic Model for the Sava River Basin List of Figures Page No. FIGURE 1: THE SAVA RIVER BASIN WITHIN THE DANUBE RIVER BASIN AND THE COUNTRIES COVERING THE BASIN. .......................................... 1 FIGURE 2: THE SAVA RIVER BASIN OVERVIEW MAP WITH MAJOR RIVERS. ............................................................................................... 2 FIGURE 3: NUMBER OF STATIONS WITH DAILY DATA ON DISCHARGE, PRECIPITATION AND TEMPERATURE IN THE DATABASE. ............................. 5 FIGURE 4: MAJOR SUB‐BASINS FOR THE SAVA HYDROLOGIC MODEL. ..................................................................................................... 7 FIGURE 5: SECOND‐LEVEL DIVISION OF THE SAVA RIVER BASIN FOR THE HYDROLOGIC MODEL. .................................................................... 8 FIGURE 6: BASIN MODELS OF THE SAVA PROJECT IN HEC‐HMS ARE LISTED IN THE LEFT PANE. RIGHT PANE SHOWS ELEMENTS OF THE SECOND BASIN MODEL. ................................................................................................................................................................. 10 FIGURE 7: USING SOURCE ELEMENTS TO REPRESENT UPSTREAM CONTRIBUTING AREAS MODELLED IN A SEPARATE BASIN MODELS: SELECTION OF THE DISCHARGE GAGE OPTION (LEFT), SPECIFICATION OF THE GAGE (TOP RIGHT), AND LINKING GAGE TO OUTPUT DATA (BOTTOM RIGHT).11 FIGURE 8: MODELLING METHODS FOR SUB‐BASINS AND REACHES ARE SHOWN IN THE LEFT PANE. ............................................................. 12 FIGURE 9: CALIBRATION RESULTS FOR THE SAVA HYDROLOGIC MODEL FOR SELECTED STATIONS. ............................................................... 15 FIGURE 10: VALIDATION RESULTS FOR THE SAVA HYDROLOGIC MODEL FOR SELECTED STATIONS. .............................................................. 16 FIGURE 11: SIMULATED VS. OBSERVED SEASONAL RUNOFF DISTRIBUTION AT SELECTED HYDROLOGIC STATIONS FOR CALIBRATION (LEFT) AND VERIFICATION (RIGHT). .....................................................................................................................................................