Estimation of annual water erosion sediments in Mu Us sandy land based on remote sensing images and coupled water-energy balance equation
Sandy lands are important geographical units in semi-arid region in northern China,and runoff is one of the main transport forces of sediments in these areas.Extraction of river network and quantitative estimation of sediment input and output caused by surface water flows are of great significance for understanding the surface dynamic process and geomorphic evolution in the Mu Us sandy land of northern China.In this study,Sentinel-2 satellite remote sensing images with a 10-m spatial resolution and Copernicus Digital Elevation Model(COPDEM)were used to automatically extract the river network in exorheic regions of the study area by a combination of water index and stream burning method.Based on the Budyko model,a method for estimating annual average water loss in semi-arid region was established by using precipitation and potential evapotranspiration data.Then,the method was used to quantitatively evaluate annual water erosion of surface sediments in the Mu Us sandy land.Our results show that the Jialu River has the highest density of river network in the exorheic regions of Mu Us sandy land,followed by Tuwei River and Wuding River,and the Kushui River has the lowest density.Under erosion and deposition by runoff,the amount of sand materials transported into the Mu Us sandy land was about 7 million t/a,the amount of sand materials eroded out of the sandy land was about 45 million t/a from 1992 to 2021,and the average annual erosion by runoff was about 38 million t.Interpretation of remote sensing images helped to add more hydrological information to obtain river network in the semi-arid regions.Based on available hydrometeorological data,average annual water erosion in the semi-arid regions is estimated.The interpretation of remote sensing images,combined with climate data ananysis(potential precipitation-evaporation balance),runoff and surface erosion model,realized a quantitative assessment of surface water erosion in the semi-arid regions.This study provides a new apporach for quantitative assessment of geomorphologic process in arid and semi-arid regions where observational data are limited.
semi-arid regionMu Us sandy landremote sensing imagessurface processstream burning
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