4.1. Factors That Contribute to Flooding in Surulere
The rainfall data analysis carried out shows that over the years, the rainfall amount in the study area has significantly
high. There has been some consistency in the rainfall pattern with slight variations. The mean monthly
rainfall is 120.2 cm while the mean annual rainfall is 1441.22 cm. (See Table 2).
Table 2 shows that the rainfall amounts over the period covered is relatively high. In the Figure 5 below, it
can be seen that over the years, Surulere has experienced a steady rise in annual rainfall, although there was a
decrease between year 1995 and 2000. However, there has been a steady increase ever since and the trend is
most likely to continue due to global warming.
The Field Survey carried out shows that a lot of houses in Surulere are constructed on drainage channels. Also,
some roads are constructed without adequate drainage channels for water flow. Some of the drainage channels
available are blocked due to continuous dumping of refuse in the channels e.g. in Cele and Itire areas.
Figure 6 displays the topography of the study area. The relief and DEM maps generated show that Surulere is
a relatively flat land, with the highest elevated peak at 100ft (See Figure 7 and Figure 8). Majority of the land
area is below 50ft (15 m); some areas are even as low as 30ft. Therefore, it can be classified as a lowland, thus
making it difficult for accumulated water from rainfall to flow to the lagoons and creeks.
The land use/land cover map generated (Figure 9 and Figure 10) shows that majority of the study area is