Limit Water Level Dynamic Control And Risk Analysis

China is a country with the shortage of water resources.In recent years,with China’s population growth and rapid economic development,the contradiction between supply and demand of water resources becomes more and more prominent.At the same time,considerable sewage and deforestation has caused serious water pollution.The ecological environment has been damaged to some extent.In order to meet the demand of the sustainable development,in the reservoir scheduling,using advanced scientific methods to improve the utilization rate of reservoir resources,to optimize allocation of reservoir resources and to display comprehensive utilization benefit of the reservoir,play a significant role to the construction of a conservation oriented society and the sustainable development strategy of water resources in China.In the past,most reservoirs control the reservoir linmited elevation in static way,which leave a lot of water before the floor season in order to guarantee the safety of the reservoir,and cause the flood resources waste.This paper employs short-term rainfall and flood forecast information to control the reservoir limited elevation.Scientific and reasonable control of reservoir limited elevation can use the overlap reservoir capacity to solve the conflicts between reservoir flood and irrigation,and then improving the utilization percent of flood and hydro-power resources.According to the actual situation of the reservoir,this paper has done the following research work:(1)Using the Shafan reservoir as an example,this thesis discuses the whole process of the dynamic control of limited water level by comprehensive,objective and scientific way.With the actual situation of reservoir and the reservoir level dynamic control method,the pill capacity-constrained pre-discharge method is used to make sure the dynamic control range of Shafan reservoir 269.06 m～72.60 m,which meet the requirements of the reservoir flood control,irrigation,water supply and normal power.After that,according to the short-term rainfall forecast and flood forecast information,utilizing the way of "pre-storage&pre-discharge" and "prevent-recharge" to come out the dynamic control of flood control level value and compared with the original planning scheduling process.The results show that using the pre-storage&pre-discharge and prevent-recharge can make the reservoir water level remains at a high level.Conventional scheduling can make the reservoir limited elevation reach 270.60 m after the flood season."Prevent-recharge" can make the reservoir limited elevation reach 272.06 m after the flood season."Pre-storage&pre-discharge" can make the reservoir limited elevation reach 272.60 m after the flood season.The "pre-storage&pre-discharge" and "prevent-recharge"can increase the reservoirs of power head,and get the most out of the reservoir water storage capacity,and improve the utilization of flood resources.(2)This thesis also combines risk analysis to determine the reliability of the dynamic control’s decision-making value,the flood forecast error is the main factors of limited water level dynamic control,and this paper adopts P-Ⅲ frequency distribution curve to calculate the extreme risk rate and to determine the risk of increasing reservoir limited elevation.The extreme risk rate Pf =0.101 and it is less than the partition criterion 0.2 by calculating,which shows that it is feasible to improve Shafan reservoir level by using rainfall forecast and flood forecast on the premise of no increasing the reservoir risk.(3)In order to further get more reasonable dynamic control range of limited water level,selecting the benefit and risk ratio as 0,3:0.7.and using the frequency analysis method combined with fuzzy mathematical analysis method determine a optimal plan.Finally we found that it is better safety and efficiency to use limited water level dynamic control range from 269.06 m to 269.06 m.(4)The dynamic control benefit is analyzed by reducing the flood water to increase water supply and power head.In order to simplify the calculation,the real benefits of the dynamic control can be calculated by converting more storage of water into the electricity price,According to the flood forecast information,using the "pre-storage&pre-discharge"to create the reservoir economic benefit value about 1.52 million Yuan.Through the study on dynamic control process,the risks and benefits of Shafan reservoir,we have a comprehensive and in-depth understanding of the dynamic control.We need to keep learning,continue to strengthen the construction of reservoir optimal operation,improving the utilization of flood resources and hydro-power resources so as to achieve a safe,stable,economical and reliable,reservoir optimization goal under the continuous development conditions.