Assessing hydro-ecological vulnerability using microwave radiometric measurements from WindSat

The spatial distribution, magnitude and timing of precipitation events are being altered globally, often leading to extreme hydrologic conditions with serious implications to the environment and society. Motivated by the pressing need to understand, from a hydro-ecological perspective, the impact of the dynamic nature of the hydrologic cycle on the environment in water-stressed regions, we investigated how different habitats in East Africa behave under extreme hydrologic conditions. We assessed the hydro-ecological vulnerability of the region by studying the response of soil moisture and vegetation water content to precipitation deficiency. The spatial patterns and characteristics of the inter-relations among the three aforementioned hydrologic variables, as well as the sensitivity and resilience of vegetation water content and soil moisture, derived from WindSat, were investigated for different vegetation types during dry spells of varying duration, identified using the Tropical Rainfall Measuring Mission (TRMM), in 2003-2011. Forest/Woody Savanna (FWS) and Savanna/Grasslands (SG) are more sensitive to local hydrologic extremes, while Shrublands (SHR) and the soils that support it are the least impacted by these conditions. SG and FWS exhibit the highest vegetation water content resilience, whereas soil moisture persistence during dry spells is at its highest in SHR/SG. The environmental variability, illustrated by the spatial patterns of the aforementioned hydrologic properties, can potentially play a role in the enhancement of resilience. This study provides critical insight into the hydro-ecological vulnerability of East Africa using microwave remote sensing, and this information can be used towards advancing management and decision support systems that would improve societal well-being and economic development.