Impact Of Land Use And Climate Change On The Spatiotemporal Changes Of Water Yield Service In The Yellow River Basin

The Yellow River Basin(YRB),the mother river of the Chinese nation,is a vital ecological corridor connecting the Tibetan Plateau,the Loess Plateau,and the North China Plain.It plays a significant role in China's economic and social development and ecological security.With the rapid growth of the social economy and population explosion in the YRB,the contradiction between the supply and demand of water resources in the YRB is getting worse.It has become one of the areas with an extreme shortage of water resources in China.Therefore,it is of great scientific significance to study the temporal and spatial variation of water yield service in the YRB and the influence of land use and climate change on it to realize the sustainable development of water resources and ecological environment protection in the YRB.In this study,based on meteorological and land use data,the models on ecosystem service,and climate changes,the YRB was selected as a case to study the temporal and spatial change characteristics of land use and climate changes.The water yield service was evaluated to show the spatiotemporal changes from 1980 to 2020.The effects of land use and climate change on water yield services were explored.Then,the water yield service under different scenarios was estimated.The preliminary conclusions are as follows.(1)We found significant spatiotemporal characteristics in land use in the YRB from 1980 to 2020.The cultivated land,forestland,and grassland were the primary land use types in the YRB,and the total area of the three types accounted for 87.82%of the YRB.From 1980 to 2020,six land use types changed to different degrees.(2)There was apparent spatiotemporal differentiation of climate change in the YRB over the past 41 years.The temperature and potential evapotranspiration in the YRB increased significantly from 1980 to 2020.The average annual temperature was high in the east YRB and low in the west,and the overall temperature increased significantly.The potential evapotranspiration was higher in the north YRB and lowered in the south,with a high value in the east and low in the west.Except for the north of Toudaoguai to Longmen and the lower reaches of the basin,the potential evapotranspiration showed an upward trend in most areas of the YRB.The precipitation decreased from southeast to northwest and dropped in the southeast of the YRB while rising in other areas.(3)There were undulating increases in the mean and the total water yield in the YRB from 1980 to 2020.The areas with a high value of average water yield were mainly distributed in the southwest and southeast YRB,while those with a low value were mainly located in the northwest YRB.There was a solid spatial positive correlation between water yield services in the YRB.The “high-high” value in water yield service areas were mainly distributed in the southwest and southeast of the YRB.(4)Land use and climate change affected the spatiotemporal changes in water yield service in the YRB.The water yield capacity of different land-use types differed from 1980 to 2020.The water yield ability of construction land was the strongest,and water was the weakest.The water yield service of the YRB was negatively correlated with air temperature and potential evapotranspiration but positively correlated with precipitation.Climate change in the YRB played a positive role in promoting the shift of water yield service,and the contribution of climate change to water yield service was far more significant than that of land use.(5)Under different land-use change scenarios,the land-use change in the YRB in 2050 shows a decrease in grassland area and an increase in the water,construction land,and unused land area.There are apparent spatiotemporal differences in water yield service under different land use and climate change scenarios in the YRB.The average water yield in 2050 reaches its maximum and the minimum value under the ND585 and EP245 scenarios,respectively.Under different scenarios,the high-value areas of average water yield were mainly distributed in the southwest and southeast YRB.The low-value regions are located primarily in the northwest of the YRB.In2050,there will still be a solid spatial positive correlation between water yield services in the YRB.The contribution of climate change to the water yield service in the future scenario(109.78?148.81%)will be much higher than that of land-use change(-48.81?-9.78%).