Increased Paved Surfaces as Major Factor of Urban Flooding in Humid Tropics: An Example from Calabar, Cross River State, Nigeria

Urban flooding is a major hydrological hazard in most cities of the humid tropics due to high

amount of rainfall, unlike in Polar Regions. However, recent increase in flooding menace has

been attributed to human activities. This paper presents new insights on the condition of the

built-up surface as the major factor of flooding in humid tropical cities using geospatial

technology, with Calabar as an example. The study area was first classified, using the

unsupervised algorithm into paved and unpaved surfaces. Nine (9) locations were then selected

randomly for in-depth study. Data were obtained mainly through satellite remote sensing and

direct field methods. In all the 9 sampled plots, the unpaved surfaces were below the

recommended Land Use Act of 1978 benchmark of not less than 36% of the total area. It was

further proven statistically that there is a significant difference between the observed unpaved

surfaces and the recommended minimum limit with 𝓧

cal (66.54) >𝓧

tab (15.507). This has

reduced infiltration component of the hydrological cycle, thereby becoming a major contributor

to increased runoff and eventual flooding. It is recommended that people‟s connection to nature

through land development should not impact negatively on thelocal hydrological cycle in the

different environments, whether at the poles or Equator, to avoid untold flood impact.

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