Evaluation of effectiveness of the water management strategies

Evaluation of effectiveness of the water management strategies with the focus on agricultural water use: A case study on Upper-Sakarya River Basin in Turkey Beyza Özel 1, Yasemin Demir 2, Oğuz Başkan 3, Emre Alp 4, * 1 Middle 2 3 4 Middle East Technical University, Department of Environmental Engineering, Turkey Soil, Fertilizer and Water Resources Central Research Institute, Turkey Siirt University, Faculty of Agriculture, Department of Soil Sciences and Plant Nutrition, Turkey East Technical University, Faculty of Engineering, Department of Environmental Engineering, Turkey * Corresponding author

OUTLINE OF THE STUDY • Specific objectives are; § to investigate linkages between the components of Water-Food Nexus in Upper Sakarya River Basin, § to address managerial problems in the region § to achieve efficient govarnence of water used for agriculture • Pressures on water resources (withdrawals, discharges) were addressed • Demands and withdrawals by all sectors were determined for current state • Demand-oriented management scenarios were developed in order to address managerial problems § improvements in the irrigation technology § shifts in the cropping pattern § water-saving irrigation strategies • The effectiveness of scenarios was evaluated using the WEAP model developed by Stockholm Environment Institute (SEI) 2

DAM KUNDUZLAR 30 Volume (hm 3) 10 5 1 0 ct -1 O 9 ct -1 O ct -0 1 -1 0 ct O O ct -1 9 ct -0 8 3 1 -1 ct 0 -1 Date O ct O O ct -0 9 8 -0 ct O -0 7 Calibrated ct O 6 -0 ct O 5 -0 ct O ct -0 4 Observed O 1 -1 ct O 0 -1 ct O O ct -0 9 8 -0 ct O O ct -0 7 6 -0 ct O O ct -0 5 4 -0 ct 3 0 3 5 -0 Volume (hm 3) 10 ct 15 100 90 80 70 60 50 40 30 20 10 0 O Calibrated 20 -0 O DAM ÇAVUŞÇU 25 O Streamflow (m 3/s) GAUGE E 12 A 052 Date -0 7 O O Date Observed ct -0 6 Calibrated ct -0 5 ct O ct ct O -0 4 3 -0 1 -1 ct O O ct -1 0 9 -0 ct O 8 -0 ct O 7 -0 ct O 6 -0 O ct 5 -0 ct 4 -0 ct O O ct -0 3 0 -0 2 ct 4 Observed O 6 45 40 35 30 25 20 15 10 5 0 O Volume (hm 3) Calibrated 8 30 8 DAM ÇATÖREN 10 O Streamflow (m 3/s) Observed O Date GAUGE E 12 A 024 12 ct -0 7 Date O 6 ct -0 O O ct -0 4 O ct -0 5 0 ct -0 Apr-12 Apr-11 Oct-11 Apr-10 Oct-10 Apr-09 Oct-09 Apr-08 Oct-08 Apr-07 Oct-07 Apr-06 Oct-06 Apr-05 Oct-05 Apr-04 0 Oct-04 1 15 3 2 Calibrated 20 ct -0 3 O 4 Observed 25 O Calibrated 5 Oct-03 Streamflow (m 3/s) Observed ct • Calibrated (2004 -2012) and validated (2013 -2016) for observed streamflow (5 gauges) and reservoir volume (3 dams) • Calibration parameters: water capacity, conductivity, initial water content, runoff resistance factor, preferred flow direction, irrigation thresholds, reservoir operations • Model performance evaluation: NSE, PBIAS, R 2 6 O MODEL CALIBRATION GAUGE D 12 A 184

WATER BUDGET SURFACE WATER Inputs (Surfacewater) Surface runoff Interflow Baseflow Çatören dam headflow Kunduzlar dam headflow Çavuşçu dam headflow WWTP discharge Urban direct discharge Net change in reservoir storage Total Inputs (hm 3/year) 0. 6 437. 5 210. 8 22. 0 28. 7 65. 4 17. 9 11. 4 1. 2 795. 4 Outputs (Surfacewater) Irrigation water supply (from river) Irrigation water supply (from pond) Livestock water supply (from river) Domestic water supply (from river) Transmission loss of irrigation water Transmission loss of domestic water Reservoir surface evaporation Total Outputs GROUNDWATER (hm 3/year) 159. 2 Inputs (Groundwater) Natural recharge Total Inputs (hm 3/year) 913. 2 Outputs (Groundwater) Irrigation water supply Domestic water supply Industrial water supply Total Outputs (hm 3/year) 215. 2 34. 4 10. 0 259. 7 28. 2 11. 4 3. 7 40. 0 16. 1 28. 4 287. 1 Available surfacewater for allocation (Total Inputs – Total Outputs) = 508. 3 Available groundwater for allocation (Total Inputs – Total Outputs) = 653. 5 4

SCENARIOS 40 Pattern change within oil seeds 35 30 Deficit irrigation within cereals 25 20 Irrigation switch from sprinkler to drip 2016 2015 2014 2013 2012 2011 2010 2009 2008 2007 2006 10 2005 15 Year 2016 2015 2014 2013 2012 2011 Combined Measures under CC 2010 Combined Measures 2009 100 90 80 70 60 50 40 30 20 10 0 2008 • Irrigation shortfall decreased by %44 -67 with combined measures; by %10 -36 with combined measures under CC Pattern change within feed crops 45 2007 • Best alternatives have been combined and investigated under CC conditions 50 2006 • Irrigation water saved up to 60 hm 3/year (~ 280 km 2 of sugar beet irrigated) 55 2005 Pattern change within feed crops Pattern change within oil seeds Irrigation switch from sprinkler to drip Deficit irrigation within cereals Irrigation water saving in hm 3 § § Decrease in irrigation shortfall (%) • Best management alternatives have been determined as: 60 Year 5

ACKNOWLEDGEMENTS We would like to acknowledge the Scientific and Technological Research Council of Turkey (TÜBİTAK) for providing funding for the project entitled ‘Evaluation of Water, Energy and Food Nexus in Sakarya Watershed’ with project number 116 Y 166. 6