Page - 528 - in Book of Full Papers - Symposium Hydro Engineering

their potential of hydropower generation could be attributed to different operational rules due to different purposes, as well as the size of the reservoirs and installed capacity of their hydropower plants. To study the reasons to that, time-series of inflow, outflow, spill and the water level in the reservoir for base period were assessed. About different water utilities, it should be noted that the Dez dam is a multi- purpose dam which provides water for different purposes, in specific time periods, to meet demands. Therefore, the releases from its reservoir are planned and only the part of release or spill, that is not greater that the penstock capacity or turbine capacity, contribute to the power generation. Also, the small capacity of its reservoir (2.7 Bm3) compared to the discharge from draining catchment (8 Bm3) causes considerable spills. Having considered that the whole capacity of its hydropower plant is relatively small compared to its inflow and releases, therefore a significant proportion of the releases or spills does not contribute to the power generation. While, the Bakhtiari reservoir with the capacity of 5.16 Bm3 and average inflow of 5.11 Bm3 can control most of the inflows with negligible spills. Also, large capacity of its hydropower plant does not pose any limit for energy production. Therefore, in case of Bakhtiari, there is a direct relationship between the changes of the rates of inflow and energy generation. Based on the simulations for future time horizons, fewer amounts of inflows and peak flows to the Dez reservoir leads to less losses through spill, which means more water could be saved in the reservoir and used to generate electricity. Considering the reasons explained above, future changes in the potential of hydropower generation, under climate change conditions, are not consonant with the changes in the inflow to the Dez reservoir. Also slight increase in the potential of hydropower generation could be attributed to the changing of the regime of discharges with smaller peaks, leading to fewer spills and remaining more water to produce electricity. Table 4 Percentage of changes in Inflow (I) and Electricity generation (E) under climate change condition Scenario- Period GCM1: ECHAM5-OM Scenario- Period GCM2: HadCM3 I (B)1 E (B) I (D)2 E (D) I (B) E (B) I (D) E (D) A1B- 2020 -7 -6.8 -4.7 2.4 A1B- 2020 -13.6 -15 -6.8 1.5 A1B- 2050 -14.9 -16.9 -8.3 2.5 A1B- 2050 -8.2 -8.4 -3.5 2.4 A1B- 2080 -19.9 -22.7 -11.5 2.3 A1B- 2080 -10.4 -11.1 -3.7 2.6 A2- 2020 -7.7 -7.6 -5.4 2.4 A2- 2020 -10.1 -10.4 -8.2 2.2 A2- 2050 -14 -16.8 -10 2.4 A2- 2050 -9.5 -10 -4.8 2.5 A2- 2080 -20.5 -23.6 -10.7 2.3 A2- 2080 -6.5 -5.8 2.5 2.2 B1- 2020 -5.9 -5.3 -3.2 2.1 B1- 2020 -10.7 -11 -9.6 2.1 B1- 2050 -15.3 -17.2 -12 2.2 B1- 2050 -1.7 -0.9 3.2 2 B1- 2080 -20.8 -24.1 -14.3 2 B1- 2080 -3.1 -2.1 3.6 1.9 1B: BAKHTIARI DAM; 2D: DEZ DAM REFERENCES 528