The inversion of soil water content by the improved apparent thermal inertia

Abstract

Soil water content is an important indicator for monitoring agricultural drought.The thermal inertia method is one of the primary means for agricultural drought assessment in low vegetation cover.This study proposes an improved calculation of the thermal inertia model.With Agricultural Ecosystem Experimental Station of Chinese Academy of Sciences in Luancheng as a base,the authors measured the thermal inertia values with different vegetation covers and different soil water content concentrations in the experimental zone by measuring model parameters and on the apparent thermal inertia model.The purpose is to find whether the thermal inertia method is applicable to the inversion of the soil water content(NDVI threshold value).The validation results show that the monitoring of soil water content of the model is feasible with high precision when the vegetation cover is low(NDVI≤ 0.35).In high vegetation cover area(NDVI0.35),the thermal inertia model fails,and hence the maximum thermal inertia approach to soil water content retrieval vegetation cover(NDVI) is set at 0.35.This method was applied to MODIS data obtained from Luancheng county,Zhaoxian county and Gaocheng city in the study area,and inversion of the area of soil water content was conducted.The results are consistent with the actual situation.Point artificial ground monitoring of soil water content yielded water content 25.1%,and the Luancheng station model calculations yielded 22.4%,suggesting good consistency.It is shown that the method has been applied well in the remote sensing data.