Study Of The Influence Of Ni'erji Reservoir On The Downstream

In recent years,the impact of human activities on the global water cycle system is more and more serious.With the growing development of river,human society is increasingly dependent on the river.Building dam is one of the most important activities in many engineering measures of river reconstruction.Ni'erji water complex is located in the the middle reach of the Nenjiang river.The controlling drainage area of Ni'erji water complex accounts for 22.4% of the Nenjiang river basin.The operation of Ni'erji reservoir has a significant effect on the downstream of the Nenjiang river in many respects,such as the runoff,the sediment and the water quality of the river.It's extremely important to study the influence of the operation of Ni'erji water complex.Based on the SWAT model and the HIMS system,this paper has analyzed the influence of reservoir operation and climate change on river runoff.The main conclusions of this paper are as follows.(1)The period before building Ni'erji reservoir is the no-reservoir period(1980-2000),while the period after building Ni'erji reservoir is the reservoir period(2007-2013).Based on the SWAT model,the results of both no-reservoir period and reservoir period showed that the efficiency coefficients and correlation coefficients of the simulation are totally in the acceptable range,the relative error value of the simulation of can meet the requirements basically except the Dalai station.(2)Based on the HIMS system,building reservoir calculation module and performing monthly runoff simulation of two periods of Nenjiang river.The results showed that the efficiency coefficients and correlation coefficients of the simulation are totally in the acceptable range and the simulation effect of HIMS system is slightly better than the SWAT model.(3)Based on the meteorological data of Nenjiang river basin from 1980 to 2013,using the Thiessen polygons and Mann-Kendall method to analyze climate change trend of the river basin.The results showed that,in recent years,there are an upward trend in the temperatures and a decrease trend in the rainfall.The climate in north basin has changed more obviously.(4)Nine climate scenarios have set up based on the analysis of climate change,using HIMS system to study the impact of reservoir operation and climate change on the river runoff.The simulation results showed that the runoff is negatively related with the temperature change and positively related with the rainfall,the operation of Ni'erji reservoir has obviously effect on the runoff of Tongmeng station.Generally,the operation of the reservoir can effectively reduce the impact of climate change on downstream runoff.