Determinants of Flooding in Port Harcourt Metropolis, Nigeria

Abstract

Flood is a natural phenomenon but human activities and interventions such as uncontrolled urbanization coupled with increased population have increased the damages and losses caused by floods. Urbanization aggravates flooding by limiting where run-off can flow and the increased impervious layers in urban areas obstruct the natural channel thereby shortening the time taken by flood water to flow into river. This study focused on analyzing the determinants of flooding in Port Harcourt metropolis, Nigeria and it revealed nine factors as being responsible for flooding in the study area. Simple percentages were used to analysed these nine factors; absence of/inadequate drainage facilities and heavy rainfall were ranked the first and second (15.74% and 15.59%) respectively. Further classification of these causes of flooding into meteorological factors, topographical factors, human factors and others, shows that human factors represents more than 2/3 of the total identified causes of flooding. Principal Component Analysis (PCA) was carried out and the nine factors responsible for flooding in the study area were reduced to four underlying dimensions (viz heavy rainfall, unplanned urban development, poor drainage quality and low-lying topography) which explain 83.20% of the total variance in causes of flooding in the metropolis. Recommendations such as implementation of the Greater Port Harcourt City Development Master Plan; instilling communal actions; demolition of illegal structures; sustainable drainage systems etc were made to curtail the perennial flooding that occur in the study area.