Djibouti is located in the north-eastern part of Africa and most of the land is covered by desert area. Although Djibouti is a country with little rainfall, the high intensity rainfall which may cause flood runoff, sometimes occurs. When such rainfall occurs in the closed watershed, rainfall water accumulates in a basin and the ponding area stays for several months. However, ponding water is lost by evaporation and infiltration to ground in a few months later without utilizing it. In order to secure irrigation water in Djibouti, we attempted to find a way to make use of the surface runoff water effectively. We selected the Kourtimalei reservoir watershed as the target area of this study. We started to record the weather data near the Kourtimalei reservoir and the water level data of the reservoir from August, 2012. We also set up rain gauges and pressure type water level gauges at three places within this watershed area in June, 2013 for observation of precipitation and temporal surface water distribution. Furthermore, we have done the field measurements on the permeability, soil texture, and saturated hydraulic conductivity of soil where the rain gauges were set. The relation between rainfall and water level at the observation point was insignificant. This result suggests that the localized runoff was a result of torrential rain within this watershed. We are in the process of collecting data, and trying to clarify the regional distribution of rain and the relationship between rainfall amount and water level of reservoir.