Multi-temporal catchment and wetland scale soil moisture and vegetation analysis in Shashe, Tugwi and Zibagwe sub-catchments of Zimbabwe

Abstract

We utilized Sentinel-1 Synthetic Aperture Radar (SAR) surface soil moisture, Sentinel-2 L1C-derived Enhanced Vegetation Index (EVI),and Soil Moisture Active Passive (SMAP) surface and root zone soil moisture data to assess soil moisture dynamics and vegetation health in Shashe, Tugwi and Zibagwe sub-catchments. Findings show that both maximum and minimum soil moisture values over different land covers experienced a declining trend from 2017 to2020, followed by a slight increase in 2021, attributed to higher rainfall during that period. Grasses (Driefontein − r ¼ 0.76; p ¼ 0.04;Intunjambili − r ¼ 0.62; p ¼ 0.00) and crops (Driefontein − r ¼ 0.77;p ¼ 0.00; Intunjambili − r ¼ 0.81; p ¼ 0.00) showed better correlation with Sentinel-1 surface soil moisture whilst trees correlated better with SMAP root zone soil moisture (Driefontein − r ¼ 0.83; p ¼ 0.01;Intunjambili − r ¼ 0.78; p ¼ 0.00). Sentinel-1 data can be effectively utilized to map wetland areas at the catchment scale, with vegetation health serving as a valuable indicator of wetland conditions.