Mapping Transient Soil Moisture Post Rainstorm Events in Hyper-Arid Karst Environments Using Multi-Sensor Observations

In hyper-arid areas, soil moisture controls surface dust emissivity, surface run-offs during flash floods, aquifers recharge, and soil induration, as well as the biological diversity of these extreme environments. Of particular interest is assessing the soil moisture spatial distribution after a rare rainstorm event in fractured karstic environments. Therefore, we use three different remote sensing methods to map the soil moisture change as well as the volumetric water content following a storm event in the hyper-arid, unvegetated, and karstic Qatar Peninsula: (1) C-band SENTINEL1 SAR backscatter intensity difference as well as its interferometric coherence, (2) Principal Component Analysis SENTINEL2-multispectral moisture index, and (3) L-band SMAP Level3 radiometer. Our results suggest that transient soil moisture spatial patterns with volumetric water content higher than 0.12 cm³/cm³ can persist longer than 48 hours following a major storm event with 50-100 mm precipitation in depressions. The above is a crucial step for assessing the origins and temporal evolution of soil moisture in Hyper-arid areas.