Study On Flood Control By Operating Cascaded Reservoirs And Their Flood Discharge Facilities

Reservoirs play a decisive role in protecting from and fighting floods,where the control and operation of the reservoir floodgates is a key part.This paper mainly works on the optimal operation problem of multiple reservoirs for flood control,which,involving extensive research scope and disciplines,is typically a nonlinear decision-making problem with multiple attributes and objectives.The previous works rarely took into account the actual operational process of individual floodgates,which therefore makes it valuable to seek solution procedures more adaptable to the actual operation of individual floodgates,and also to make the theoretical study more applicable to engineering situations.Targeted at six cascaded reservoirs located in the lower and middle reaches of the studied basin,this paper formulates two models: the optimal operation of multi-reservoirs and multi-floodgates for flood control,which are used respectively to determine the flood discharges from reservoirs and the operational process of individual floodgates during a planning horizon in flood season.The main works and contributions of this paper are summarized as follows:(1)The piecewise linear approximation techniques for a single variable are skillfully integrated into the mixed integer linear programming(MILP),which is employed to solve the optimal operation model of multi-reservoirs for flood control by calling a professional optimization solver.This improves the model in solution efficiency and formulation simplicity.(2)After the flood control schedules of multiple reservoirs are determined,this paper takes into account how to control the floodgates,and raises an optimal operation problem of multiple floodgates,with an objective to minimize the shutdown and startup frequency of individual floodgates.Solving the problem determines the actual operational process of floodgates,which can provide intuitional decision support for shift engineers.(3)The piecewise linear approximation techniques are extended to handle double variables,and a triangle analytical method is introduced to determine the opening degree of individual floodgates.A larger temporal scale is suggested for the optimal operation problem of multiple floodgates,which can be solved more efficiently to give results more adaptable to the practical requirements from the scheduling decision-makers.(4)The MILP is more often used in dealing with the unit commitment problems in hydropower systems.With application of the MILP to the flood control operation of multiple reservoirs,specifically to the six cascaded reservoirs located in the lower and middle studied basin,this work tested and verified the effectiveness and feasibility of present models and their solution procedures in solving the operational problems of multiple reservoirs for flood control.