Quantitative Monitoring And Analysis Of Soil Erosion Based On MT-InSAR

As a geomorphic process persistently occurring over the earth's surface,soil erosion is one of the most serious environmental problems in the world nowadays,seriously threatening agriculture,natural resources,and ecosystem environments.Soil erosion generally results in topography changes of the loss area,which destroys the integrity of the ground,leads to degradation of land quality,triggers geological disasters such as collapses,landslides and mudslides,and makes river sediment accumulation aggravate flood disasters.Therefore,high-precision monitoring of topography is the most direct and effective method to obtain quantitative results of soil erosion.However,the existing soil erosion monitoring methods are based on filed observations or empirical models,and it is difficult to achieve high precision quantitative estimation.Time series InSAR is an advanced space geodetic technology that has developed rapidly in the past ten years.It can not only obtain tiny surface deformation,but also obtain the time series of surface deformation.Therefore,this paper using time-series InSAR technology to achieve quantitative monitoring and analysis of soil erosion.The main work and contributions of this paper are as follows:(1)Taking the East Dongting Lake basin as an example to study the soil erosion of seasonal lakes,considering the alternating characteristics of the East Dongting Lake's flood and dry seasons,the data of the flood and dry periods are processed by the SBAS-InSAR method.The results show that the soil erosion areas during the dry season are mainly concentrated at the junction of the catchment area and the floodplain,which along the curved river.The most serious soil erosion during the dry season is the year of 2018,and the maximum soil erosion rate exceeds-5mm/month.During the flood season,soil erosion is concentrated around the external drainage network.The most widely distributed soil erosion during the flood season is the year of 2019,and the maximum soil erosion rate exceeds-6 mm/month.(2)Based on the characteristics of Wind-water Erosion Crisscross Region in the Loess Plateau,a time series InSAR model based on meteorological factors was constructed to replace the traditional SBAS-InSAR linear deformation model,and time series analysis of surface changes in the study area was carried out.The results show that the cumulative deformation is close to-200 mm during the three and a half years at the maximum deformation in our model,which is mainly caused by internal conditions,water erosion and wind erosion.The deformation rate caused by internal factors is nearly-15 mm/year,caused by water erosion is between-0.03-0.02 mm/mm,wih the water erosion at the most serious area is close to-60 mm.During the study,wind erosion when the factor changes by 1 unit,the deformation range is about-0.3-0.2mm,with the wind erosion at the most serious region is near to-50 mm.(3)Through the analysis of soil erosion combined with meteorological data,we found that there is a relationship between rainfall and soil erosion in East Dongting Lake basin.For example,soil erosion and rainfall events are positively correlated during flood periods,it is means that rainfall events trigger soil erosion;on the contrary,in dry periods,soil erosion and rainfall events are negatively correlated.The more the number of trace rainfalls,the less obvious the soil erosion and the less rainfall during the dry season.The soil erosion is more obvious.For wind-water erosion crisscross region,precipitation and wind erosion are both important causes of soil erosion.