Jornal de Riscos Ambientais

Environmental and Rainfall Intensity Analysis to Solve the Problem of Flooding in Owerri Urban

Abstract

Nwachukwu MA, Alozie CP and Alozie GA

Hardships, economic wastes, and loss of lives due to yearly Owerri urban flooding pose a challenge to environmentalists. In this study, environmental field investigation, analysis of drainage and reliable rainfall data (2006-2013) were carried out. Drainage blocked with refuse, buildings obstructing natural drainage, increasing urban cementation and the low topographic landscape of Owerri urban were observed as major causes of the flooding. A flood risk map showed Owerri urban as vulnerable. Analysis of rainfall intensity (RI) revealed a tradition of one year drop after two years of rising. Change in RI from the one year of the drop to the two years of the rise was observed in a fairly decreasing order (41%-23%). Hyetographs showed the highest peak of RI in July 2006 measuring 595.l mm/ hr. and lowest in May 2013 with 330.7 mm/hr. with a 3-phase drainage network channeling runoff to Nworie River, flooding in Owerri urban will come to an end. The law allowing ≤ 70% of impervious surface per developed plot of land should be enacted and be enforced to support natural infiltration.