Analysis on Spatiotemporal Variation of Soil Moisture and Its Influencing Factors in Weihe River Basin
[Objective]The aims of this study are to reveal the temporal and spatial variation characteristics of soil moisture in the Weihe River Basin,to clarify the main factors affecting soil moisture changes,so as to provide scientific basis for effective monitoring of agricultural drought in the Weihe River Basin.[Methods]Based on the MODIS NDVI,LST data and climatic data of Weihe River Basin from 2000 to 2020,integrated trend analysis and geographic detector,the NDVI-Ts characteristic space was constructed,and the spatiotemporal variation of soil moisture and its driving factors were analyzed.[Results]In the past 20 years,the soil moisture in Weihe River Basin showed a significant downward trend at the rate of 0.004 9/a,and there was an obvious drying phenomenon.In different land use types,the soil moisture contents in the past 20 years followed the order:woodland＞grassland＞cultivated land＞urban and construction land.The overall dry and wet grade was mainly normal(0.4≤TVDI＜0.6).The low value areas of soil moisture mainly distributed in the west and north of Weihe River Basin,and the high value area primarily concentrated in the southeast and northwest edge areas.In the sub-basins,the proportion of drought area in the main basin of Weihe River showed an upward trend,in which the decreasing trend of soil moisture in Guanzhong Plain located in the south of the main basin of Weihe River was the most significant.According to the influence analysis of detection factors,it was found that elevation,the average temperature and the potential evapotranspiration were the main factors affecting soil moisture distribution in Weihe River Basin,and their explanatory power was significantly higher than that of other factors.Factor interaction analysis showed that the combination of the average temperature and the cumulative precipitation had a significant effect on the spatial distribution of soil moisture in Weihe River Basin.[Conclusion]Soil moisture in Weihe River Basin had decreased significantly in the past 20 years,and there was an obvious drying trend.The change of soil moisture in Weihe River Basin was mainly affected by topography,geomorphology and meteorological factors.
soil moistureTVDIWeihe River Basinspatiotemporal distributiongeographic detector
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