Study On The Law Of Water Cycle Elements In Chungling Water Basin Under The Changing Environment

Global climate change and the intensification of human activities are the major environmental problems facing human society at present.Under the influence of changing environment,the river runoff process also showed a certain regular change.ChungLing watershed belongs to Xiangjiang sub Basin,Floods are frequent,therefore,it is necessary to explore the evolution law of hydro meteorological elements in the basin.This study is of great significance to guide the healthy development of ecological environment,the rational exploitation and utilization of water resources and the sustainable development of river basin economy and society.This paper definds the upper reaches of OuYanghai hydrological station in the Chungling watershed as the study area.The research data include precipitation data of 12 rainfall stations,annual runoff data of 4 hydrological stations,meteorological data of 3 meteorological stations and remote sensing image data of 3 periods,And the data were analyzed for watershed surface precipitation data,annual runoff data,average temperature,annual evapotranspiration and land use data for three periods.In this paper,linear regression method,M-K trend test method,R/S analysis method and SRST model are used to analyze the change characteristics of hydro meteorological factors in the year,season,flood season and non flood season scale,Cumulative interval method combines slip T to test the mutation points of the sequence,and wavelet analysis is used to study the periodic variation of the sequence,Secondly,through correlation analysis and grey correlation method,the correlation between climate factors and runoff and grey relational grade are discussed,The effect of human activity factor on runoff was analyzed by land use change.Finally,the influence of climate change and human activities on runoff is analyzed quantitatively by means of the elastic coefficient method.The main conclusions are as follows:(1)The precipitation in Chungling watershed showed an increasing trend,and there was no significant mutation.(2)The four sites of Maojun,Feixian,Jiahe and Ouyanghai were respectively decreasing,increasing,decreasing and decreasing.None of them were significant.Except for Maojun station,the other three sites were mutated in 1991.The multi time scale analysis shows that the main period of precipitation is about 10 years,and the runoff has the same main cycle as precipitation.(3)During the study period,the average temperature of the basin increased significantly,and all seasons showed an upward trend,consistent with the general trend of global warming,and the temperature will continue to rise in the future,And the average temperature sequence in 1996 was significantly mutated.The periodicity of the sequence is about 28 years.(4)The Potential evapotranspiration in the basin decreased,but the temperature increased.There was a phenomenon of evaporation paradox,The sequence has mutated in 2003 and is the same as the temperature cycle,which is about 25 years.(5)This paper adopts a method integrating qualitative analysis with quantitative analysis to analyze the effect of climate change and human activities on runoff.The results show that precipitation is the most significant factor affecting runoff,the correlation between runoff and grey relational degree is the largest,followed by potential evaporation and temperature.Through the analysis of land use patterns,it is found that the continuous decrease of cultivated land and the increase of forest land and construction land during the 1990?2010 period are the reasons for the increase of runoff.Quantitative analysis showed that climate change accounted for 89%of the factors affecting runoff,and human activity accounted for only 11%.Therefore,climate change is the main factor affecting runoff,and precipitation has the greatest impact on Runoff.