Modeling the impacts of urbanization on river flooding using the saint venant equations

Urbanization and expansion of structural developments into traditional flood prone areas of a natural river channel modifies the channel shapes, reduces the width of the flood prone areas relative to bankfull width at every point along the river channel and modifies the flood flows containment characteristics of the channel. These impacts are manifested the entrenchment ratio. In this study the Continuity equation in the St. Venant hydrodynamic equations was modified for the geomorphological parameter called the entrenchment ratio. The modified model was applied to investigate the extent of inundation of the floodplain by floods of various frequencies over the section of the Kaduna River adjoining the Kaduna City where urbanization has over the year caused the floodplain to be developed for residential accommodation, recreational and agricultural activities. Results obtained indicated that the 2yr, 5yr, 10yr, 25yr, 50yr, and 100yr floods when occur can cause maximum inundation of between 82.53% to 94.48% of the floodplain area between the Eastern Byepass bridge and the Kaduna South Waterworks with Ungwan Rimi, Kabala Doki and Kigo road extension as the most critical areas.