Evaluating the Impacts of Flooding on the Residents of Lagos, Nigeria

Globally, flooding is one of the most common environmental hazards resulting in property damage and destruction, population displacement, disruption to day-to-day life, illness and fatalities. Lagos is the most populous city in Nigeria as well as Africa with over 20 million inhabitants and this population has been projected to rapidly increase in the future. The increase in the frequency and severity of flood events in Lagos, therefore, emphasises the need for better flood management practices. The aim of this thesis is to assess the current flood situation and flood management in five areas of Lagos: Ikeja, Ikorodu, Lekki, Surulere and Victoria Island. A questionnaire survey was conducted with residents in all five areas which differed in population density and income level in order to understand their perception of the flood problem as well as their experiences of flooding. Flood managers were also interviewed in order to better understand the flood management situation from the perspective of the government officials. Daily precipitation data for Ikeja and Victoria Island stations from 1981 to 2015 were analyzed to determine seasonality and identify whether there have been changes to rainfall characteristics leading to flooding including changing seasonality, frequency and intensity of rainfall. Results revealed overall about 79% of the respondents across the five areas had experienced flooding while living in Lagos. Of which 65% of respondents in Lekki, 61% in Ikorodu, 60% in Victoria Island, 59% in Surulere and 54% in Ikeja had experienced flooding in their current property. Areas such as Lekki and Victoria Island, although, high-income areas in Lagos, are characterized with rapid and unplanned development like Ikorodu, a low-income area. They are low-lying and as such flood-prone especially as the right flood defence measures are lacking. Despite this, Lekki and Victoria Island remain a well sought-after area. Respondents also revealed health problems, displacement, property damage and disruption to movement as the impacts of flooding experienced. Overall, more men suffered flood impacts compared to women. Location did not have an impact on the flood impacts experienced. Residents believed heavy rainfall was the main cause of flooding in all five areas. Similarly, the flood managers believed heavy rainfall was responsible for the frequent cause of flooding but proposed factors such as increased urbanization, development on floodplains, blocked drainages contribute to the issue of flooding in Lagos. The rainfall data results did not show there had been an increase in the amount of precipitation, there was also no significant relationship between annual and seasonal rainfall with flood events.