Effects Of Vegetation Distribution And Landscape Pattern On Water Conservation In The Dongjiang River Basin

As an important component of ecosystem services,water conservation plays an important role in regulating flood disaster and maintaining ecological security.The process of water conservation is affected by multiple factors such as natural and human activities,and the change of landscape pattern and vegetation coverage NDVI is the most significant manifestation of human effects on surface ecology,which has an important impact on the process of water cycle.As one of the four tributaries of the Pearl River,the stability and health of water resources in the Dongjiang River have an important impact on the production,living and ecological water use of nearly 40 million people in the southeast coastal areas of China.Based on this,the relationship between landscape pattern characteristics,vegetation cover change and water conservation spatial response in the Dongjiang River Basin was explored in this paper.The results are as follows:(1)The deterministic coefficient R~2 and efficiency coefficient Eash-Sutcliffe of SWAT model of Boluo station,Longchuan station,Heyuan station and Lingxia station in rate periodic and validation period meet the adaptability requirements.The model has high simulation accuracy and can accurately reflect the spatial and temporal distribution characteristics of the hydrological cycle in Dongjiang River Basin.(2)The average water conservation in the Dongjiang River Basin from 2001 to 2020 is925.44mm,which is 4.95 times of runoff and 1.58 times of evaporation,showing a strong water conservation capacity.The interannual variation showed no significant upward trend,and the change rate was 0.12mm/10a.The spatial distribution pattern is middle reaches>lower reaches>upper reaches.(3)NDVI averaged 0.73 from 2001 to 2020,and showed an upward trend in the past 20years,with a change rate of 0.04.The results of spatial autocorrelation showed that NDVI of high,medium density forestland and grassland was significantly positively correlated with water conservation.The water conservation capacity per unit area was medium density forest land>high density forest land>low density forest land>grassland.GWR results showed that there was a positive correlation between NDVI and water conservation of different vegetation types in sub-basins,and the spatial distribution of regression coefficients decreased from upstream to downstream.(4)The autocorrelation between landscape level index and water conservation space showed that water conservation was negatively correlated with patch density PD,fragrance diversity index SHDI,scatter and coincident index IJI,and positively correlated with maximum patch index LPI,similar proximity ratio PLADJ,and sprawl index CONTAG.GWR results showed that LPI,CONTAG,IJI were negatively correlated with water conservation in the upper reaches of the basin and the mountainous and hilly region in southeast China.The negative correlation between SHDI and water conservation was concentrated in the middle and lower reaches.(5)PLAND,ED,and LPI were positively correlated with water conservation,while PLAND,ED,and LPI were negatively correlated with water conservation.GWR results showed that LPI,PLAND,and water conservation regression coefficients decreased northward in the middle reaches,while ED decreased southward to northeast.PLAND,ED,LPI were negatively correlated with water conservation,with positive correlation mainly concentrated in the upper reaches of the basin.PLAND,ED,LPI are negatively correlated with water conservation,and the regression coefficients show a growing negative correlation from downstream to upstream.