Impact Of Environmental Change On Multi-scale Runoff Variation In Jialu River Basin

Runoff will change significantly under the combined effect of human activities and environmental changes.Research on the driving mechanism of water cycle under changing environment will be carried out to quantitatively distinguish the impacts of climate change and human activities on runoff changes,it is of great significance to the development,utilization and rational allocation of water resources in the basin.The ecological environment of the Some Random Place Somewhere is fragile,and there are problems such as water shortage,soil and water loss and desertification.The study on the driving force of runoff under the changing environment of the region is an important part to explore the mechanism of regional water cycle.This paper takes the Jialuhe River Basin as the research object,carries on the analysis and research from the year and the season many time scales,based on the hydrometeorological element evolution characteristic analysis,the influence of environmental change on runoff variation was quantitatively studied by using Budyko water-heat coupled equation,cumulative slope rate of change method and abed hydrological simulation method.The main achievements are as follows:(1)The trend analysis of hydrometeorological elements is carried out by means of Mann-Kendall,linear regression and spelman rank test,etc.,it was found that the annual and seasonal runoff series in the Jialuhe River Basin showed a significant downward trend,while the precipitation,temperature and potential evapotranspiration series showed an upward trend The precipitation-runoff bi-cumulative curve method and the sliding F test method were used to diagnose the variation points of the annual runoff series,the variation points of runoff in wet season and dry season were verified in 1972 and 1984 respectively.(2)Analysis of land use and vegetation cover in the Jialuhe river basin based on land use and Ndvi data shows that between 1985 and 2015,the amount and spatial variation of land use types in the Jialuhe river basin affected the formation and change of runoff to a certain extent,and the overall vegetation coverage changed well from 1993 to 2014.(3)According to the vertical decomposition method based on the water-heat coupling equilibrium equation of Budyko,human activities are the main factors leading to the reduction of annual runoff,the contribution rate is about 74.9%,and the contribution rate of climate change is about 25.1%;According to the elastic coefficient method,the contribution rates of the variation of underlying surface conditions,precipitation and potential evapotranspiration to runoff reduction were 77.54%,21.31%and 1.15%,respectively Based on the cumulative slope change rate method,the contribution rate of annual runoff reduction influenced by human activities is 88.78%,that of potential evapotranspiration is 1.55%,and that of precipitation is 9.67%.(4)The impacts of climate change and human activities on annual and dry and wet season runoff are quantitatively distinguished by the abcd model and the seasonal vertical decomposition method based on the extended Budyko model.Human activities cause the decrease of runoff in the annual,wet and dry seasons,but the degree of decrease is different,and the greatest decrease occurs in the wet season,it increased most in wet season,followed by dry season.