Remote sensing of land use-land cover change and climate variability on hydrological processes in Sub-Saharan Africa: key scientific strides and challenges.

The impact of land use land cover (LULC) change and climate variability on water resources poses as a major threat in semi-arid environments, especially in the sub-Saharan Africa. Countries in sub-Saharan Africa are vulnerable to water scarcity. Hence, there is an urgent need for understanding the various methods for LULC change and climate variability assessment, to aid in water resources management at various scales. Various studies have modelled and assessed the effect of LULC change and climate variability on hydrological responses, using different approaches. In this regard, this paper provides a detailed review on the progress of various remote sensing techniques in modelling and assessing the effect of LULC change and climate variability on hydrological processes. The review also highlights the critical scientific strides and challenges of remotely-sensed applications in LULC change characterization and total evaporation estimation. Specifically, research gaps in the estimation of total evaporation in response to LULC change and climate variability, using remote sensing are also highlighted. The study demonstrated remotely-sensed methods used in hydrologic models such as the SCS-CN, WetSpa, JULES and the SWAT model that are used to determine run-off and streamflow. These methods have a component of total evaporation however evapotranspiration (ET) is not the sole focus. The study showed that the application of the remotely sensed SEBS tool has been widely accepted as a viable method to estimate total evaporation. However, it has been observed that there is limited focus on the impact of LULC change and climate variability on total evaporation. [ABSTRACT FROM AUTHOR]