Effects of precipitation on vegetation and surface water in the Yellow River Basin during 2000–2021

The Yellow River Basin (YRB) is a vital ecological zone in China owing to its sensitive and fragile environment.Under the long-term influence of climate changes and artificial factors,the relationship between precipitation,vegetation,and surface water in the YRB has changed drastically,ultimately affecting the water resources and environmental management.Therefore,we applied multivariate statistical analysis to investigate the precipitation,normalized difference vegetation index (NDVI),and surface water changes in the YRB from 2000to 2021.Furthermore,we attempted to clarify the ecological effects of precipitation by explaining the relationship between precipitation and vegetation in terms of the time-lag relationship using the Integrated Multi-satellite Retrievals for Global Precipitation Measurement algorithm,Moderate Resolution Imaging Spectroradiometer,and hydrological databases.Precipitation,vegetation,and area of surface water in the YRB showed increasing trends from 2000–2021 (e.g.,7.215 mm/yr,0.004 NDVI/yr,and 0.932 km2/yr,respectively).The water level in the upper reaches of the YRB showed a downward trend,whereas that in the middle and lower reaches exhibited an upward trend.Changes in precipitation had a positive effect on vegetation and surface water in the YRB,with correlation coefficients of 0.63 and0.51,respectively.The responses of NDVI and surface water elevation to precipitation were heterogeneous and delayed,with the majority showing a lag time of approximately≤16 days.Moreover,the lag times of Longyangxia Lake and Ngoring-Co Lake were 0 and 8 days,respectively.We showed that precipitation variability can effectively explain vegetation improvement and increases in surface water elevation,while providing a proven scenario for predicting the surface water and vegetation productivity under the influence of climate change.