Riparian corridors encroachment and flood risk assessment in Ile-Ife: a GIS perspective

Recent development and expansion of paved surfaces as a result of urban growth has resulted in encroachment of riparian corridors, the immediate effect of which poses flood risk to affected areas. Geographic Information System (GIS) method was employed in this study to determine the level of encroachment as well as areas susceptible/at risk to flood and flooding. Results from the study indicated that urban and agricultural land uses had encroached significantly on the riparian corridor and had disrupted the ecosystem services of the corridor. Results also indicated that major parts of the watershed had low flood risk but serious encroachment exists therein. Buildings as many as 1129 had already encroached into the 30 metres minimum setback standard which are mainly riparian corridor and the buildings which had encroached into the corridor fall within the high flood risk zone of the watershed.