Page - 526 - in Book of Full Papers - Symposium Hydro Engineering

Table 2 Percentage of changes in temperature (∆T) and precipitation (∆P) under climate change condition Scenario- Period GCM1: ECHAM5 GCM2: HadCM3 ∆T (%) ∆P (%) ∆T (%) ∆P (%) T1 M2 S 3 B4 T M S B T M S B T M S B A1B- 2020 0 4 3.1 6.4 2.4 -2.5 2.8 1.4 -0.1 3.7 2.8 6 5.9 0.4 7.6 3.8 A1B- 2050 12.5 18.1 15.6 19.5 7.4 -0.1 7.7 3.1 11. 3 16. 6 14. 4 18.1 9 2.8 8.9 6.1 A1B- 2080 28.4 32.3 28 32.3 8 1.4 7.7 4 21. 2 27. 8 24 28 10. 2 5.8 11. 2 9.5 A2- 2020 0 3.9 3 6.3 2.3 -3.5 2.9 0.1 0.5 4.4 3.5 6.9 -0.2 -5 0.8 -1.9 A2- 2050 10.1 15.4 13.2 16.9 3.8 -2.1 4 0.7 10. 3 15. 5 13. 3 17 6.7 1.2 7.7 5.2 A2- 2080 27.7 35.5 30.9 35.4 9.2 1.1 10.3 5 26. 8 34. 3 29. 8 34.1 16. 8 10. 7 18. 4 15. 9 B1- 2020 0 3.9 3 6.2 4.3 -2 4.9 1.2 -0.2 3.5 2.7 5.8 -1.8 -5.6 -1.2 -2.8 B1- 2050 6.6 11.4 9.6 13 1.2 -6.1 1.7 -2.7 8.3 13. 1 11. 1 14.6 12 7.4 13. 3 10. 7 B1- 2080 16.4 22.6 19.5 23.2 3.4 -4.1 3.6 -1.4 13. 6 19. 1 16. 3 19.9 14. 3 8.8 16. 2 12. 6 1T: TIREH; 2M: MARBEREH; 3S: SAZAR; 4B: BAKHTIARI; 3.2. HYDROLOGICAL SIMULATION UNDER CLIMATE CHANGE SCENARIOS To simulate runoff, First, the HBV model calibration and validation carried out using 12 and 5 years of observed discharge data, respectively. The values of Nash- Suttclif statistics of 0.69, 0.60, 0.61 and 0.6 and R2s of 0.71, 0.61, 0.63 and 0.61 obtained for Tireh, Marbereh, Sazar and Bakhtiari, respectively. After ensuring the efficiency of model, it was applied to simulate discharge under climate change condition with projected T and P time-series as inputs. The overall changes of the annual flow corresponded to all GCMs and scenarios show that the amount of annual discharge is mostly decreasing in the future; as the reductions are most significant for 2080’s time horizon. In Tireh, the greatest reduction of annual flow (19%) is attributed to ECHAM5-B1-2050 and 2080. Similar to Tireh, the reduction of annual flow in Marbereh is more significant in 2080’s as it reaches to 26% (ECHAM5-A2-2080). Generally, the amount of annual flow mostly decreases in Sazar. However, some contrasting results obtained, indicating annual flow increase up to 13% (HadCM3-A2-2080). The greatest reductions of annual flow (up to 17% by HadCM3-B1), is corresponded to 2020’s time horizon. Also, the greatest reduction of annual flow in Bakhtiari is up to 27% by ECHAM5-B1 in 2080’s. 526