Study On Ecological Flow Of Cascade Hydropower Station In Xushui River Basin

The small hydropower station plays an important role in power generation and irrigation,but also changes the natural hydrological situation of the reach,and it is easy to form a dehydration-reducing reach between the dam site and the workshop,which affects the survival of the downstream organisms.The minimum ecological discharge of hydropower station is an important guarantee to maintain the health of downstream ecosystem.It is important to study and analyze the minimum ecological discharge of hydropower station to maintain the stability of downstream ecosystem.Based on Xushui cascade hydropower stations in river basin as the research object,on the basis of summarizing the ecological flow research progress at home and abroad,choose appropriate ecological flow calculation method for the calculation of hydropower station,after considering all kinds of methods of calculation results,the recommended value of hydropower stations or ecological flow rate from,formulate Xushui flow cascade hydropower stations in river basin ecological discharge drainage standard,The main conclusions of this paper are as follows:(1)The hydrological station of Youshuijie is selected as the reference station of Guanyinxia Hydropower Station,Heixiazi Hydropower Station,Baxianyuan First and Second Hydropower Station,and the hydrological station of Shengxiancun is selected as the reference station of Majiagou Hydropower Station,Baiguoshu Hydropower Station,Shiba Hydropower Station and Shuangxi Hydropower Station.Based on the measured runoff data from 1959 to 1998 at Youshuijie hydrological station and from1957 to 2002 at Shengxiancun hydrological station,the annual average runoff,annual runoff at different frequencies and average runoff in the driest month at different frequencies are obtained by hydrological comparison method.(2)The ecological discharge of Guanyinxia,Heixiazi,Baxianyuan-first and Baxianyuan-second,Majiagou,Baguoshu,Shiba and Shuangxi hydropower stations are calculated by the methods commonly used in hydrological method.By comparing and analyzing the calculation results of various methods,it is found that the calculation results of the 90%guarantee rate and Texas method are less applicable when calculating the river ecological discharge with obvious seasonal variation trend.The calculation results of base flow proportion method and annual distribution method are most reasonable.(3)The ecological discharge of Guanyinxia,Heixiazi,Majiagou and Shuangxi hydropower stations is calculated by using the wet circle method in the traditional hydraulic method.According to the basin cherish protect fish,view sound gorge hydropower station is chosen Brachymystax lenok tsinlingensis pink as indicator species,black son gorge hydropower station choose Hucho bleekeri as indicator species,majiagou hydropower station instructions for Onychostoma macrolepis fish species,respectively in different ecological hydraulic hydropower station in fish spawning period and calculated method flow of ecological spawning period should be over.(4)Experts and scholars and hydropower station staff are invited to rate the importance of indicators of different calculation methods according to the characteristics of different hydropower stations.According to the weighted average of the scoring results,the recommended ecological discharge values of Guanyinxia Hydropower Station,Heixiazi Hydropower Station,Baxianyuan-First and Baxianyuan-Second Hydropower Station,Majiagou Hydropower Station,Baishuoshu Hydropower Station,Shiba Hydropower Station and Shuangxi Hydropower Station in non-flood season are 0.67 m~3/s,1.38 m~3/s,1.42 m~3/s,1.71 m~3/s,2.02 m~3/s,2.09m~3/s,2.37 m~3/s,and 2.65 m~3/s;The recommended value of ecological flow in flood season is 1.51 m~3/s,2.66 m~3/s,3.79 m~3/s,4.54 m~3/s,5.11 m~3/s,5.99 m~3/s,6.79 m~3/s and7.10m~3/s.(5)In calculating the ecological discharge of the cascade hydropower station in the valley of Xushuihe,the ecological discharge can be calculated by the method of ecological hydraulics if there is demand for living things downstream of the dam site,and the method of proportion of base flow can be used to calculate the ecological discharge when there is no demand for living things downstream of the dam site.In non-flood season,the standard of ecological discharge discharge of hydropower stations should be 10%of the average annual discharge,and in flood season,the standard of ecological discharge discharge discharge of hydropower stations should be20%～30%of the average annual discharge.