Constructing and operating cascade reservoirs significantly contribute to comprehensive basin water resource management, while altering natural hydrological regimes of rivers, which imposes negative impacts on riverine ecology. The main aim of this study is to synergistically optimize the objectives of increasing hydropower generation and alleviating hydrological regime alteration for cascade reservoirs. This study first proposed a dynamic time warping scenario backward reduction (DTW-SBR) framework to extract streamflow scenarios from the historical streamflow series regarded as benchmarks for calculating deviation degrees of hydrological regimes. Then a multi-objective long-term operation model considering the hydrological regime and hydroelectricity was formed for minimizing the deviation degrees of hydrological regimes at the downstream section (O1) and maximizing the hydropower generation of cascade reservoirs (O2). The non-dominated sorting genetic algorithm-II (NSGA-II) combined with the long-term conventional operation (CO) rules of cascade reservoirs was adopted to produce the Pareto-front solutions to derive the recommended policies for guiding the long-term operation of cascade reservoirs. The six large reservoirs in the middle reaches of the Jinsha River, China with a 10-day runoff dataset spanning from 1953 to 2015 constitute a case study. The results showed that nine streamflow scenarios were extracted for calculating the O1 by the DTW-SBR framework, which could reflect the intra- and inter- annual variability of hydrological regimes at the Panzhihua hydrological station. The Pareto-front solutions obtained by the NSGA-II revealed competitive relationships between the O1 and O2. As compared to the long-term CO rules of cascade reservoirs, the O1 value could be reduced by up to 42,312 (corresponding rate of 10.51%) and the O2 value could be improved by up to 1752 × 10⁸ kW·h (corresponding rate of 5.14%). Based on the inclination to be dominated by different objectives, three typical operation schemes, A, B and C, were chosen from the Pareto-front solutions; Scheme A could be considered as the recommended solution, which simultaneously reduced the O1 value by 23,965 with the rate of 5.95% and increased the O2 value by 1752 × 10⁸ kW·h with the rate of 5.14%, as compared to the long-term CO rules. This study can provide references on boosting the synergies of hydropower production and hydrological regime restoration for the long-term ecological operation of cascade reservoirs.

On the basis of river-lake relationship analysis, this paper chose the middle and lower reaches of Yangtze River where the Poyang Lake locates as the study area. The storage variable of Three Gorges Project was deduced to hydrological stations at the lower reaches. The natural runoff processes of hydrological stations were restored. Then RVA method was applied to analyze the hydrologic alterations of river channels at the hydrological stations before and after reservoir operation. The analysis result indicated that Hankou hydrological station and Datong hydrological station at the lower reaches had medium changes after operation of the Three Gorges Project. The hydrological regimes of Hankou hydrological station, Hukou hydrological station and Datong hydrological station in different periods before and after operation of Three Gorges Project were analyzed, the water exchange between Poyang Lake and the middle and lower reaches of Yangtze River was investigated, and the relevant results indicated that the inflow of lower reaches river channel decreased during impoundment of Three Gorges Project, the water level of river channel dropped, and the outflow from the lake increased, which was the major reason behind water deficiency of Poyang Lake area. The recommendation is to optimize the Three Gorges Project's water storage scheme, so as to improve the river-lake relationship at the middle and lower reaches of Yangtze River.

Guo, W.; Xu, G.H.; Shao, J.; Ouyang, S.; Du, T.; Wang, K., and Bo, H., 2020. Simulation of flood process based on the model of improved barrier lake's gradual dam break model. In: Guido Aldana, P.A. and Kantamaneni, K. (eds.), Advances in Water Resources, Coastal Management, and Marine Science Technology. Journal of Coastal Research, Special Issue No. 104, pp. 172–177. Coconut Creek (Florida), ISSN 0749-0208.This paper considers coupling the formula proposed by the Railway Research Institute and Xie Renzhi's gradual dam break model, and puts forward an improved barrier lake's gradual dam break model. After simulating the dam break flood of the “11.3” Baige barrier lake in Jinshajiang basin, it is found that the simulation results are similar to the measured rise duration and post-peak duration, and the error range does not exceed 5%, and the pre-peak and post-peak water discharge is less than 15% compared with the actual measurement. The practicality of the proposed model is verified by this example, and it can be used for the rapid calculation of the dam break flood.

Experimental ecological scheduling study on cascade hydropower station considering both fish spawning and hydropower generation