Topoclimate, and more precisely orographic rains on windward slopes and leeward rain shadow, controls the spatiotemporal variability of rainfall, vegetation, and hydrology in tropical mountains. Such variability has a substantial societal impact. For instance, they can cause differences in wealth of rain-fed farmers among the windward and leeward sides of a mountain. However, due to lack of detailed scientific knowledge, a “one-size-fits-all” agro-ecosystem management approach has so far been used in determining priority zones for conservation and distributing agricultural inputs, without considering rainfall variability. This project is therefore aimed at understanding topoclimatic effects on rainfall distribution and the subsequent impacts on vegetation cover and surface hydrology over the Ethiopian mountain massifs. A multidisciplinary approach will be adopted to reach the overarching goal, including analysis of rainfall distribution and seasonality using the ALARO-0 model and statistical matching with characteristics of natural vegetation and surface runoff.