Flood mitigation has become paramount for most towns and cities around the world to safeguard people against loss of lives and property. The work assessed the feasibility of reducing flood impact in the Nyando Catchment, located in the western part in Kenya through the adoption of scenarios such as implementing dykes, dredging, green storage and by-passes. The Duflow software, a hydraulic simulation model for 1-dimensional hydrodynamic modelling of water movement and catchment runoff, was used for the modeling. This work provides useful information for water resource planners and decision makers in developing effective flood mitigation plans. Aside this, the work also provides easy to follow procedure for Catchment Delineation, Thiessen Polygon Analysis for areal rainfall, Projection Transformation, using output from ArcGIS in Google Earth and SRTM data download for delineation of catchment and processing of Areal rainfall using ArcGIS.