Estimation of volumetric soil water content over the Liudaogou river basin of the Loess Plateau using the SWEST method with spatial and temporal variability

Monitoring soil moisture with spatial and temporal distribution is in big demand in arid and semi-arid regions. In Loess Plateau in China, where soil erosion is a major issue, information about soil water content helps in the planning of regional water resources and vegetation restoration for the prevention of erosion. In this study, we have developed the SWEST (soil water estimation from surface temperature) method by integrating well-known relationships among surface temperature, evapotranspiration and soil water content. An advantage of the proposed SWEST method is that it can estimate soil water content for the location of a water source of evapotranspiration, where there would be a near-surface for bare soil and the root zone for well vegetated surfaces. A verification study conducted at Liudaogou River Basin of the Loess Plateau, China, indicated the method could estimate soil water content accurately, with an estimation error of about 2.6% of the total volume of soil. Application of the method to satellite thermal imaging successfully presented the applicability of the SWEST method to estimate soil water content with spatial and temporal variability.