The landuse/cover changes in the Ethiopian highlands have significantly increased the variability of runoff and sediment fluxes of the Blue Nile River during the last few decades. Lack of insights on the catchment behaviour has been challenged decision makers of watershed managers and downstream irrigation infrastructure managers. Understanding the long-term variations of those fluxes and identifying the major causes is crucial to support optimal water management in the region. This book applied three methods (Statistical, Physical based models and landuse detections) to identify the trends/changes of the fluxes and underline the driving forces for the changes. The results of the statistical tests, SWAT model, and landuse change detection confirmed that landuse change have resulted in significant increase of runoff generation and sediment load from the Upper Blue Nile Basin. This is an important finding to guide optimal water resources development in the whole basin, both upstream in the Ethiopian highlands, and further downstream in the plains of Sudan and Egypt.