New Approach of Rainfall-Runoff Estimationfor Blue Nile Basin using GIS and WMS Integration
The Watershed Modeling System (WMS) is a hydrological modeling mediator for all phases of watershed hydraulics and hydrology. At the same time, there is an obvious increase in use of Geographic Information System (GIS) in hydrological applications as it has the ability to gather data rapidly. In this study, WMS was integrated with GIS to determine the surface runoff from the Blue Nile basin located in the northeast of Ethiopia. Hydrologic Engineering Center (HEC-1), among WMS models, was chosen to be used. The morphological parameters of the basin were estimated. The geographical area of Blue Nile basin is 324,000 km2. The rainfall data for five years were utilized for simulation and determination of surface runoff for the study area. Oudin’s method was used to estimate total potential evapotranspiration. The results of this research showed that the average annual volume of surface runoff from the Blue Nile basin is 55.18 BCM. The annual amount of direct runoff represents 10% of total annual rainfall. The results also indicated that WMS is effective in the domain of water resources management as it is specialized in digital hydrological systems. The approach of this research can be applied for estimating runoff volume in other watersheds.
Keywords - Watershed, Runoff, WMS, GIS, HEC-1, Morphological.