Analysis Of The Impact Of Land Use And Climate Change On The Temporal And Spatial Changes Of Water Yield In Hangzhou

Natural factors and land use are two major drivers of ecosystem services change.We analyze the temporal and spatial variation characteristics of water yield and its main driving factors,which has practical significance for maintaining urban soil and water conservation.Taking Hangzhou as an example,this study adopted methods of landscape pattern analysis,spatial gradient analysis,correlation analysis,and contribution quantitative analysis.With the support of InVEST model,ArcGIS and Fragstats,this dissertation identified the characteristics of land use change and climate change in Hangzhou,and evaluated the variation of water yield in time and space.The correlation between water yield and meteorological factors and landscape pattern indices was analyzed by SPSS.It was also explored that the climate change and land use change contributed to water yield.Results of this research showed as follows:(1)The most dramatic change of land use in Hangzhou from 2000 to 2015 was the conversion between cultivated land and construction land,with the highest retention rate of forest land.The landscape showed a stronger trend of fragmentation and heterogeneity.(2)From 2000 to 2015,the annual precipitation in Hangzhou decreased first and then increased.The annual average temperature was fluctuating upward,and the annual potential and actual evapotranspiration were both fluctuating.The annual precipitation did not change noticeably in the urban center.The annual average temperature decreased significantly far away from the urban center.The annual potential evapotranspiration continued to increase,while the actual evapotranspiration first decreased and then increased.(3)The water yield in Hangzhou showed a first decline and then upward trend during from 2000 to 2015.The water yield was spatially high in the northeast and low in the southwest,and increased first and then decreased far away from the city center.Construction land had the largest water yield among all land use types.(4)The correlation between water yield and meteorological factors was greater than that of landscape pattern indices.Water yield had the strongest positive correlation with precipitation in meteorological factors.The distance of 10-20 km away from the city center was the turning point of landscape pattern in main urban area while the distance of 10 km away from the city center was the turning point of water yield.(5)The contribution of climate change to the water yield in Hangzhou was greater than that of land use change to it.But within 10-20 km of the city center,the positive contribution of land use to water yield change became more and more significant.This study provided a scientific basis for the development of rational water supply and use to achieve ecological balance in the urban area.It also had implications for understanding the mechanisms of maintaining or improving urban ecosystem services,and promoting sustainable development of urban areas.