Research On The Risk And Benefit Of Adjusting The Flood Control Level In Reservoir

The problem of water resource is very serious in Haihe River Basin. But for thesafety of flood control, many reservoirs keep a very low water level in flood season,so that the stored water is variously wasted. In order to make the best use of the floodresource, as well as not to endanger the downstream area, a research on the risk andbenefit of adjusting the flood control level is carried out in this paper. Some methodsof analyzing the risk of flood control have been systematically investigated based onrelevant research results and the principle of risk benefit analysis. According to theactual conditions of Dongwushi reservoir, some hydrological theories and methodshave been proposed to study the characteristic of the flood and the division of theflood season in the reservoir. Further, with detailed analysis on the risk and the benefitof adjusting the flood control level, a comprehensive fuzzy model of assessment isestablished to demonstrate the best adjusting level. The main content and results inthis paper are:(1) Based on the analysis of the geographical features and the characteristics ofthe flood in the target area, fuzzy set theory is introduced to calculate the fuzzymembership grade of the flood season.(2) Based on the actual conditions of Dongwushi reservoir, the control of floodof different frequencies is modeled. With the highest water level that appears in theflood control model, the flood-caused economic lost in the region around the reservoiris analyzed. Further, the statistics relation of the maximum down-poured waterquantity and the lost at downstream area is established, so that the mean lost and risklost at different flood control level can be estimated.(3) The impact on the water supply and power generation of the reservoir isstudied, and detailed calculation about the excess benefit compared with the currentsituation in different flood control level is done. By input-output analysis, possibleplan of level adjusting is decided.(4) Based on the research done above, comprehensive fuzzy assessment methodis introduced to establish the assessment system to decide the best adjusting level.(5) The conclusion of this paper is: From the viewpoint of risk and benefit, theflood control level of Dongwushi reservoir should be kept at a level of 104 meter. Ifthe water level is kept higher than that, the risk will rise so fast that it will soon weighdown the benefit.The methods and models used in the paper can provide scientific help inassessing the adjusting of flood control level.