Watershed Parameters to Flood Discharge Modeling at Wodeba River Newly Constructed Bridge in Wolaita Zone Damot Pulasa Woreda,Ethiopia

Urban river bridges are prone to flood risk as result of high flow from the upper part of Watershed. Watershed Length, shape, area and slope are very important parameters affecting the timing and magnitude of the flood discharge contributed from the watershed outlet .Flooding frequently occurs in Wodeba River due to large watershed draining to the location of newly Construction Bridge. This research has applying hydrologic modeling to determine the flooding discharge newly constructing bridge designed location. In order to determine the derive watershed parameters i.e. longest flow length [L], watershed centroid length [L c ], average slope of watershed slope [S w ] and area [A] of watershed, Geographical information system (GIS-10.4.1) by using digital elevation model has applied .Snyder’s method of hydrologic method was applied and determined the peak discharge of 1564.75m 3 /s at bridge location by suing watershed parameters of Longest flow length [L), Centroid distance (Lc) Area [A] and average channel slop are 30.77Km,17.25km, 142.25Km 2 and 30% respectively .The result of the study indicates that the area contributing the runoff to bridge location is high that result vulnerable to flooding during maximum probable precipitation and the steep slop of watershed resulted high response to peak discharge.