Geography Reference
In-Depth Information
Single carriage road has a total length of 246.41 km (81.9 percent)
exposed to flood risk (Table 4). This information will greatly assist planners
and decision makers on how to allocate resources pertaining to flood
eventuality, the road category to be given first attention based on the carriage
capacity and level of usage.
In addition, in a case of ad hoc mitigation plan and impact reduction, this
information will be useful for prioritizing and selecting infrastructures serving
areas of higher population concentration and high valued economic centers.
For instance, the multiple dual carriage roads that connect the heavy density
Lagos Mainland area with Lagos Island are of high economic value and high
priority linkage because they connect the high density Islands to the other parts
of the city.
Evidence from Figure 12 reveals that such accessibility infrastructures
crosses the five-class potential risk zones at both sides (edge of Lagos Main-
land and Island) for a distance running to 1.2 km. A total of 0.61 km of rail
track in the region is vulnerable to the hazard, of this 6.4 percent lies within
the low risk vulnerability class while 93.6 percent lies within the very low risk
vulnerability class. These sections are the two railway terminals, located at the
Lagos Mainland near the shoreline of the Lagos Lagoon (Figure 12).
5.3. Spatial Analysis and Estimation of Potentially Vulnerable
Population
Susceptibility of population to flooding is the major propellent of studying
flood disaster and finding mitigation measures. Hence, it has become a widely
used concept in flood risk management and vulnerability assessment.
Table 4. Exposed road infrastructure by priority and vulnerability class
Length of road exposed to flood risk (km)
Dual carriage Single carriage
Very high 8.07
(2.7)
17.51
(5.8)
High 13.77
(4.6)
27.32
(9.1)
Moderate 8.07
(2.7)
37.58
(12.5)
Low 9.89
(3.3)
60.32
(20.0)
Very low 14.73
(4.9)
103.68
(34.5)
Total 54.5
(18.2)
246.41
(81.9)
Note:
values in parentheses are the corresponding percentage values.
Vulnerability class
