Nomadic responses to rainfall: Nighttime light evidence from wadis in Djibouti

Abstract

This study examined the association between human activities and precipitation in dry areas, focusing on nomadic people in Djibouti. Nomadic communities often lack access to essential social services, and water resource management is crucial for their survival and social welfare. Understanding how they respond to variations in water availability could contribute to effective policy implementation. Using satellite-derived information, this study found that nighttime light brightness increased in response to precipitation around wadis, with potential water spring locations, and decreased with distance from a wadi. Specifically, we observed no effect when the distance was more than 5 km. Furthermore, no effect of precipitation was found in urban areas, while a positive effect was found in remote areas. These findings suggest that the activity of nomadic people increases around wadis in response to increased water resource availability, indicating that water supply is important for settlement projects because it can reduce water-seeking costs and improve social welfare. This study provides the first empirical evidence using satellite data and statistical analysis to show that water availability is critical for nomadic communities which can inform better resource management and policy decisions in African countries.