Quantitative Analysis Of The Effects Of Climate Change And Human Activities On The Runoff In The Shiyang River Basin

The impacts of climate change and human activities on water resources have received extensive attention worldwide,profoundly affecting the evolution law of water resources in river basins and the transformation mechanism of water cycle,and thus changing the spatial and temporal distribution pattern of water resources.So how to quantify the impact of climate change and human activities on runoff has become an urgent scientific problem for inland river basins in cold and arid regions.Therefore,taking Shiyang River Basin as the study area,this paper collected the data of runoff,temperature,precipitation,potential evapotranspiration,land use and hydropower development,and analyzed the spatial-temporal variation characteristics of runoff in main stream and tributaries of Shiyang River Basin during 1959-2020 by using linear regression method,inverse distance weighting method and Morlet wavelet analysis.Then,M-K mutation test,land use dynamic attitude and transfer matrix were used to explore the effects of climate change and human activities on runoff.Finally,based on Budyko hypothesis,the contribution of climate change and human activities to runoff in Shiyang River Basin was quantitatively analyzed.The main conclusions are as follows:(1)Based on the analysis of the spatial-temporal variation characteristics of runoff in the Shiyang River Basin from 1959 to 2020,the annual runoff showed a decreasing trend(0.04×10~8 m~3/10a),and the spatial pattern showed a decreasing pattern from southwest to no rtheast.Since 1990,the runoff of Shiyang River Basin has accelerated obviously,and the main stream of Shiyang River has the most significant growth rate.The runoff growth rate from 1991 to 2020 is 1.81 times of that from 1959 to 1990.The interannual v ariation range of runoff in the upper reaches is relatively small,while that in the middle and lower reaches is relatively large.Runoff is mainly in wet years,normal years and low years,accounting for 76%of the total basin.(2)According to the study on the influence of climate change on runoff in Shiyang River Basin from 1959 to 2017,the temperature,precipitation and potential evapotranspiration showed an increasing trend at the rates of 0.355℃/10a,7.44mm/10a and 8.46 mm/10a,respectively.The distribution pattern of temperature and potential evapotranspiration decreased from north to south,and the distribution pattern of precipitation decreased from south to north.Temperature and potential evapotranspiration decreased from north to south,while precipitation decreased from south to north.The temperature is the highest in summer and the lowest in winter,the precipitation and potential evapotranspiration are the maximum in summer and the minimum in winter.Most of the abrupt changes in temperature occurred in the late1990s,precipitation in the 1980s and 1990s,and potential evapotranspiration in the1990s and after 2005.(3)Through the analysis of the impact of human activities on runoff in the Shiyang River Basin from 1980 to 2020,t he land use type area is in descending order of unused land,grassland,cultivated land,forest land,construction land and water area.The area of cultivated land and construction land increased in different degrees,while the area of other land types dec reased.The construction of hydropower stations in the basin was concentrated from 2004 to 2011,covering a total area of 102.84hectares.The water quality and soil of hydropower station are in good condition,and hydropower development has little influen ce on water quality and soil.(4)Based on the Budyko hypothesis,the contribution of climate change and human activities to runoff in the Shiyang River Basin was quantified.The contribution rate of climate change and human activities to runoff in the ups tream is81.17%and 18.83%,respectively.The main factor of runoff change is climate change;the contribution rates of climate change and human activities to runoff in the middle and lower reaches were 15.83%and 84.17%,respectively.Among them,the main factor of runoff change in Dongda River Basin is climate change,among which precipitation has the greatest impact on runoff change.The main reason for the change of runoff in Xiying River,Jinta River,Zamu River,Huangyang River and Shiyang River is human activities,and the change of underlying surface leads to the change of runoff.Climate change and human activities have become the main factors affecting the runoff change of inland river basins in cold and arid regions.The results of this study will provide parameter support for quantifying the impacts of climate change and human activities on runoff of inland river basins and model construction,and provide scientific basis for rational allocation,planning management and sustainable development of water resources in arid inland river basins.