Tính toán đánh giá lại tần suất lũ hồ dầu tiếng so với thiết kế và có xét đến biến đổi khí hậu
Abstract
During Dau Tieng reservoir’s opperation, there are many studies on flood simulation and flood forecast to propose appropriate solutions on reservoir’s regulationfor flood discharge downstreamand flood reductionin downstream areas, especially in Ho Chi Minh City.
The article summarizes the results of the re-evaluation of flood frequency of Dau Tieng reservoir considering climate change (CC) for flood regulation problem.This isthe result of state-level scientific research project KC08.07/16-20 "Research and propose solutions to improve water use efficiency, ensure the safety of main works and downstream Dau Tieng reservoir in the conditions of climate change and extreme weather ".
This study used observed rain data for 40 years (1977-2016), used NAM model to calculate flood flow and analysed flood frequencies. Considering CC, the rainfall in the flood season increases from 38.6 to 56.1% (threshold of 90%) in meteorological stations in the Dau Tieng basin corresponding to the high emission scenario (RPC8.5).The comparison results show that corresponding to the scenario RCP4.5, flood peak discharge at rare frequencies, corresponding to the return periods from 100 years to 10,000 years (1% to 0.01%) correspondingly increased from about 11 to 15% and in the RCP8.5 scenario from 20 to 24%. However, compared to the design phase of Dau Tieng reservoir, the results show that for all rare flood frequencies, the flood peak discharges reduced 30% and 10% in everage without and with RPC8.5 scenario. The consequence is the issue of the flood-related problems in Dau Tieng Reservoiris "much less stressful". For instance, the excess flood discharge and the level of flood inundation downstream (including Ho Chi Minh City) caused by flood discharge would be much lower than previous simulation.
Key words: Dau Tieng reservoir, flood frequency, climate change, rainfall increase in flood season, inundation reduction, Lower Sai Gon – Dong Nai river basin
