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Adaptive reservoir flood limited water level for a changing environment
- Zhang, Xiaoqi, Liu, Pan, Wang, Hao, Lei, Xiaohui, Yin, Jiabo
- Environmental earth sciences 2017 v.76 no.21 pp. 743
- case studies, climate change, floods, humans, risk, stream flow, China
- As streamflow is non-stationary due to climate change and human activities, adapting reservoir operation in the changing environment is of significant importance. Specifically, the flood limited water level (FLWL) needs to be re-established to ensure flood safety when the reservoir inflow is altered. The aims of this study are: (1) to clarify the relationship between the FLWL and streamflow when statistical parameters of the flood peak and volume vary through time and (2) to re-establish the FLWL when the reservoir inflow changes under the non-stationary condition. The adaptive FLWL is derived based on flood routing of non-stationary design floods, and the flood risk probability is then estimated. With China’s Three Gorges Reservoir (TGR) as a case study, the changing pattern of FLWL is quantified when statistical parameters (i.e., mean, [Formula: see text] and [Formula: see text]) of design floods have a linear temporal trend. The results indicate that the FLWL is sensitive with design floods, i.e., (1) means of design flood peak, 3-day volume, 7-day volume, 15-day volume and 30-day volume yearly decrease by 33 m³/s, 0.008, 0.021, 0.482 and 0.905 billion m³, respectively, (2) when the non-stationary design flood is used, the cumulative flood risk probability of the reservoir water level exceeding 175.0 m during 2011–2030 decreases from 1.98 to 1.82% with the conventional FLWL scheme and (3) the FLWL of the TGR could be re-set without increasing the flood risk probability, and the FLWL would increase about 4.7 m by 2030 in this non-stationary streamflow scenario. These findings are helpful to derive the FLWL in a changing environment.