Investigation On Water Environment And Water Conservation At The Source Of Fenhe River

Fenhe River,as the second largest tributary of the Yellow River,has been playing an important role in the economic development of Shanxi Province.However,in recent years,with the vigorous development of tourism economy and the intensification of human activities,the water environment at the source of Fenhe River has been destroyed,and the water conservation capacity has declined,which has also had a negative impact on economic development.Therefore,it is urgent to study the protection of water environment at the source of Fenhe River.Therefore,it is urgent to study the protection of water environment at the source of Fenhe River.In this paper,the source of Fenhe River is taken as the study area,through field investigation and collecting relevant data,the current water environment situation in the study area is understood,and the spring flow,river ecological flow,water quality and pollution capacity of Leiming Temple in the study area are studied,and some suggestions on water environment protection in the study area are put forward.The research results are as follows:(1)Through field investigation and collecting relevant data of water resources development and utilization in the study area,this paper makes clear the present situation of development and utilization of Leimingsi spring,Damiao River and Beishi River.With the outflow of rural population in the study area,the development and utilization degree of Damiao River and Beishi River is low,while the development and utilization degree of Leimingsi Spring is high due to the influence of Leimingsi Water Diversion Project.In addition,the villagers in the Damiao River Basin freely raise livestock and discard garbage into the river,which has an impact on the water quality of the Damiao River.The water quality of Beishihe River was also affected by the villagers’planting crops and dumping domestic garbage in the river channel,which polluted the water quality in the lower reaches of Leimingsi spring.(2)By collecting rainfall data of four rainfall stations in the study area,this paper calculates rainfall in the study area by using Tyson polygon,and regards Leimingsi spring area as an independent system.By using water balance method,the runoff data of Leimingsi spring series are calculated.Based on the long series runoff data of Leimingsi spring,the grey GM(1,1)model is constructed,and the spring discharge from 2013 to 2017 is predicted by two simulation schemes:year by year and month by month.According to the comparison of residual test,the qualified rate of simulation by month is much higher than that by year,which is more in line with the actual situation.Therefore,the simulation is carried out on a monthly basis,and the grey GM(1,1)model of each natural month is constructed to predict the discharge of Leimingsi spring from 2018 to 2025.The results show that the seasonal variation of spring flow in Leimingsi spring is obvious.The spring flow is larger from July to September,with an average of 0.39m~3/s,and smaller from December to January,with an average of 0.025 m~3/s.(3)By collecting the runoff data of Chashang Hydrological Station in the study area,combined with the runoff data of Leimingsi spring,this paper adopts four hydrological methods,namely,minimum monthly average method,flow duration curve method(FDC method),annual distribution method and Tennant method to calculate the minimum ecological flow in the lower reaches of Leimingsi spring in Beishi River and Damiao River respectively.The results show that the minimum monthly average method is the smallest among the four methods,and the minimum ecological flow is only 0.5 m~3/s.The trend of the minimum ecological flow calculated by FDC and annual distribution method is similar,and Tennant method is the largest,with the minimum ecological flow of 6.47 m~3/s.However,only some months in FDC method are similar to Tennant method,and the minimum ecological flow calculated by other three methods is far lower than Tennant method.(4)In this paper,through field sampling investigation,seven sampling points of water samples were set up,and some indexes such as COD,BOD5,total nitrogen and total phosphorus were detected.The water quality in the lower reaches of Beishi River,Damiao River and Leimingsi spring was evaluated by single factor evaluation method,pollutant comprehensive index method and Nemerow index method,and the pollutants exceeding the standard in water samples were determined according to the designated water quality objectives.A one-dimensional water quality model was established to calculate the pollutant carrying capacity of the pollutants exceeding the standard in the downstream water samples of Beishi River,Damiao River and Leimingsi spring.The results show that BOD5 and total nitrogen in Beishihe River was larger than the reference value,and the total nitrogen content seriously exceeds the reference value.The BOD5 and total nitrogen content in Damiao River exceeded the standard.COD content and total nitrogen content in the lower reaches of Leimingsi spring was larger than the reference value.The BOD5 capacity of beishi river is42.59t/a,and total nitrogen capacity is 6.58t/a.The pollutant carrying capacity of BOD5 and total nitrogen in Damiao River is 60.3t/a and 1.71 t/a respectively.In the lower reaches of Leimingsi Spring,the capacity of COD and total nitrogen is 1220.3t/a and 42.14t/a respectively.