Modeling precipitation and land use impacts on water routing infrastructure for a Nigerian city

Keywords: Urban flooding, Water Resources, Cities, Land use, Nigeria, Africa
Abstract Type: Virtual Paper Abstract

Abstract

Hydrological modeling allows the representation of complex water resources systems using empirical relationships. Such models are able to simulate the response of a watershed to variability in climate parameters like precipitation, as well as landscape factors such as soil and land use. In the developing world and especially in sub-Saharan Africa, cities are expanding outwards at a rapid pace. Roadways often become flooded as the existing water channeling infrastructure is unable to convey the rapid rate of runoff generated from the increase in impervious surfaces. Modeling the quantity of flood waters and impact on human transport is difficult because of the often reduced availability and reliability of daily climate data inputs or streamflow data for model calibration. In West Africa and Nigeria which is the focus of this study, sparse and sometimes nonexistent data is an impediment to effective hydrological modelling. In this study, the use of remotely sensed rainfall and land use data as inputs for improved urban flood modeling was evaluated. This was achieved by comparing a weighted combination of gridded rainfall datasets to the performance of a single long-term local rainfall station for the characterization of spatial extent of flooding and flood heights at bridge crossings within the Ona river basin in Ibadan Nigeria. Based on flood heights and bridge dimensions, it was also possible to compare the routing capacity at bridges to flood water volumes. Locations where existing bridges (mostly built in the 1970s) are inadequate for the increasingly urbanizing landscape where then established.