Flood hazard mapping in Mkondoa river prone area between Kilosa and Gulwe at Wami river sub basin.

The heavy downpours associated with El-Nino conditions resulted in many parts of East Africa receiving above average rainfall in 2009 to 2011. Kilosa District was the worst hit, as the Mkondoa River burst its banks causing extensive flooding to the surrounding areas including Kilosa town and displacing 23,980 peoples from their homes, infrastructures were sworn out including cutoff of railways line and roads. The main objective of study was to determine the depth and extent of flood along Mkondoa River between Kilosa and Gulwe. The methodology used for the study included river cross-sections survey from upstream to downstream which was 85km,flood frequency analysis and hydrodynamic modeling. Flood frequency analysis was done in Easy Fit Software, using the annual maximum daily flow from 1952 to 2012peak flow were 24.093 m3/s, 63.17m3/s, 115.11 m3/s, 235.67m3/s, 390.94m3/s and 634.89 m3/s for 2, 5, 10, 25, 50 and 100 years return period respectively. In hydrodynamic modeling, surveyed data for river cross sections were used to create river geometry built in HEC-RAS model, discharge data were imported into HEC-RAS, water surface elevations were created for the selected peak flood quartiles for 2, 5, 10, 25, 50 and 100 years return periods. The produced flood hazard Extent showed inundation depth from 0.01 m to 2.52 m. The flood hazard map produced will save as a planning and decision tool for more effective flood management in Mkondoa area.