Study On Spationtemporal Changes And Driving Factors Of Water Conservation Service Value In The Source Area Of The Yellow River

Water conservation is one of the most important service functions of ecosystems,and the economic value estimation of water conservation functions caused by climate change and human activities has always been a hot research topic.Studying the spatiotemporal changes and driving factors of water source conservation and service value has important theoretical and practical significance.This study is based on daily meteorological data in the source area of the Yellow River,constructs a SWAT model,and quantitatively analyzes the spatiotemporal evolution characteristics of water conservation and service value in the source area of the Yellow River using water balance method and shadow engineering method.On this basis,combined with meteorological factors and land use types in the source area of the Yellow River,correlation analysis,cross wavelet transform,and geographic detectors were used to attribute the value of water conservation services in the source area of the Yellow River in both time and space.The main conclusions are as follows:(1)The annual average temperature,annual maximum average temperature,and annual minimum average temperature in the source area of the Yellow River showed an upward trend from 1970 to 2019.From the distribution within the year,the highest temperature in the three series of years appeared in July,and the lowest temperature appeared in January.The spatial distribution shows a gradually increasing pattern from west to east The annual precipitation,flood season precipitation,and non flood season precipitation all show an upward trend,with significant fluctuations in annual precipitation.The trend of changes between flood season precipitation and annual precipitation is highly consistent,and the changes are basically consistent.The three sequences all exhibit a spatial distribution pattern of more in the east and less in the west,and more in the south and less in the north.The annual potential evapotranspiration in the source area of the Yellow River fluctuates greatly and shows an overall upward trend.High values occur in the northern region,while low values occur in the western region.(2)Build a SWAT model suitable for the source area of the Yellow River,and divide it into a period of 2000-2015 for the rate period,and a period of 2016-2019 for the verification period.The Nash efficiency coefficients of the three hydrological stations during the rate period are 0.75,0.76,and 0.80,respectively,and the Nash efficiency coefficient during the verification period is 0.76.The determination coefficient and relative deviation also meet the simulation accuracy requirements.(3)The overall water conservation amount and service value in the source area of the Yellow River show a fluctuating upward trend,with an average annual water conservation amount of 168.39mm and a water conservation service value of 125.09 billion yuan.The spatial distribution is characterized by more in the east and less in the west,with more in the south and less in the north,decreasing from the middle to the surrounding areas.There are significant differences in water conservation and service value among different ecosystems,with forest land,grassland,unused land,and cultivated land ranking from high to low in terms of water conservation and service value per unit area.(4)In terms of time,the synergistic relationship between the value of water conservation services and precipitation in the source area of the Yellow River is strongest,with Spearman coefficient and Pearson coefficient both above 0.75.The cross wavelet results show that there is a resonance period between the two,and the phase change is the same,indicating a significant positive correlation between the two.From a spatial perspective,the factors that have the greatest impact on the value of water conservation services in the source area of the Yellow River are precipitation and potential evapotranspiration.The interaction detection results show that all influencing factors have a dual factor enhancement after pairwise interaction.The factor with the strongest explanatory power for the spatial change of water conservation service value has significant differences in the mechanism of action compared to other factors in the ecological detection results,indicating that the factors in the Yellow River source area that play a dominant role in the spatial change of water conservation service value have a unique mechanism of action.