Potential of thermal remote sensing techniques in monitoring waterlogged area based on surface soil moisture retrieval

摘要

The aim of this paper was to test the capability of thermal remote sensing in monitoring waterlogged areas in Ismailia governorate based on surface soil moisture retrieval. Three landsat satellite images 5, 7 and 8 (TM, ETM + and TIRS) were used for this purpose during three different dates (1998, 2008 and 2015). Soil moisture index (SMI) was produced based on calculated Land surface temperature (LST). Fifty five soil profiles have been dug to measure the depth of water tables of the study area. SMI Validation was carried out in 2015 using surface soil samples from the upper 5 cm in which actual moisture content was estimated. Digital change detection techniques for SMI were applied in order to monitor the change in the surface soil moisture along two time periods (1998-2008), (2008-2015). The results indicated that the spatio-temporal variations of soil moisture content are associated with soil texture, landuse/landcover, soil elevation and water table levels. Correlation between actual and retrieved soil moisture revealed a moderate correlation relationship with R-2 = 0.61. Furthermore, an increase of water table eastern the study area. Also the results illustrated the increasing of water table is a direct relation with soil moisture. In addition, an increase in the surface soil moisture (SSM) recognized in 22.06% of the study area from 1998 to 2008 while, 40.55% of the area showed an increased in the SSM from 2008 to 2015. This continuous increase in the SSM could be prone to the increasing agricultural expansion and water table levels which, led to conversion of sabkhas to water bodies and fish farms. SMI could be an effective tool in mapping waterlogged areas.