Monitoring Stations for Runoff and Sediment Transport along Gumara River (Tana Basin): Procedures and Preliminary Results

Gumara River, one of the major tributaries of Lake Tana, drains an area of 1768km2. It is within the growth corridor of Lake Tana Basin, where an increasing number of water resource development projects (mainly hydropower and irrigation) take place. Monitoring stations for runoff and sediment have been installed under Wase-Tana Project along Gumara River using automatic water level recorders to produce data of finer resolution (10 minutes duration) and ordinary staff gauges (maximum of three readings a day).Depth integrated suspended sediment samples have also been collected. This study presents an assessment of variation of different time scale discharge measurements and adjustments (refinements) for the daily discharge data acquired through manual records of the staff gauges. Preliminary analysis of the discharge and sediment data collected was made. The hydrograph shows that the mean daily discharge values from the automatic recorders are greater than the daily values of the staff gauges for almost all of the times of record (nearly 50% increment). A good correlation has been found between the two methods (the correlation coefficient, R2 =0.79) and the difference is much appreciated during the rainy seasons. A wide range of suspended sediment concentrations (6-6654mg/L) were obtained during the time of record.status: publishe