| In the past decades,the runoff measured by the main hydrological stations in the northern basins of China has shown an obvious trend of decline.As the most representative basin in the north of China,The Rocky Mountainous Area of North China is the water conservation area that vulnerable to the impact of human activities and climate change.So the contradiction of water resources is the most prominent problem.This study uses hydrological simulation to analyze the runoff attenuation of Sha-Tang river mountain watershed.The influence was also study mechanism of runoff attenuation in the soil-rock mountains of North China was studied.The main results of the study are as follows:(1)The daily runoff and monthly runoff measured at Wangkuai Reservoir Station and Xidayang Reservoir Station,as well as the maximum peak flood discharge measured by Fuping Station,showed a significant decreasing trend during 1960 to2018.And the measured runoff and peak flood discharge obvious changed in 1996.The precipitation series showed a downward trend from 1956 to 2018.The runoff coefficient showed a decreasing trend from 1960 to 2018,and the flood discharge capacity was declining.(2)The SWAT model of Shahe-Tanghe mountain watershed was established,and the model was calibrated and verified by monthly runoff.The results show that the R~2and NS of Wangkuai Reservoir Station and Western Ocean Station are greater than 0.7in the regular period,and the R~2and NS of the verification period are greater than0.65,indicating that the model simulation effect is good.Through scenario simulation,the impacts of human activities and climate change on runoff change in the study basin were separated.The contribution rates of climate change and human activities to runoff change were 25.39%and 74.61%in the upper reaches of the Tanghe River Basin,and 39.93%and 60.07%in the upper reaches of the Shahe River Basin,respectively.The main driving factor of runoff attenuation was human activities.(3)Combined with investigation and statistical analysis,the influence mechanism of underlying surface type change and water conservancy project construction operation on runoff is expounded.According to the annual land use data from 1982 to2015,the area of grassland decreased significantly,while the area of cultivated land and woodland increased.The proportion of grassland decreased by 30%,that of woodland increased by 28.6%,and that of cultivated land increased by 1.4%.According to the monthly average NDVI values from 2000 to 2015,the vegetation coverage of the basin showed an increasing trend in the past 15 years,and the regions with increasing vegetation coverage were similar to those with increasing forest area.Combined with the variation law of runoff coefficient and the research results of other scholars,it is believed that the increase of woodland area and the restoration of vegetation cover are related to the decline of runoff capacity.(4)Since 1960,61 small reservoirs,15 hydropower stations,31 pumping stations and 103 sluices have been built in the basin.From 2006 to 2018,the main surface water consumption in the Shahe-Tanghe mountain basin studied was agricultural irrigation,with an average consumption of about 117 million m~3.During1960-1979,the water consumption was about 72 million m~3,with an increase of about45 million m~3 from the base period to the change period.The reservoir capacity intercepted runoff was about 60 million m~3.In the study basin within Baoding City,the influence of water conservancy projects on runoff is about 105 million m~3,and the rest of runoff variation may be affected by other factors and the water conservancy projects in the study basin within Shanxi Province.There are 33 figures,18 tables and 117 references in this paper. |
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