TITLE:
Spatial Distribution Pattern and Terrain Analysis of Urban Flash Floods and Inundated Areas in Maiduguri Metropolis, Borno State, Northeast, Nigeria
AUTHORS:
Mohammed Abba Jimme, Abbas Bashir, Abel Aderemi Adebayo
KEYWORDS:
Flashfloods, Urbanization, Vulnerability, Terrain Analysis, Maiduguri DTM
JOURNAL NAME:
Journal of Geographic Information System,
Vol.8 No.1,
February
29,
2016
ABSTRACT: Maiduguri metropolis
Nigeria, lies on a relatively flat terrain of about 350 meters above sea level
and is part of the undulating Borno Plain that slopes towards the Lake Chad. The
rapid physical expansion of the metropolis and the annual recurrent flash
flooding and inundation problems within the city continues to impact
devastating socioeconomic effects on the livelihood of residents sometimes
leading to loss of lives and property. It is important therefore to understand
the spatial pattern of floods and terrain characteristics in Maiduguri for
planning purposes. The paper examined the spatial pattern of urban flash floods
and inundations, and the terrain characteristics in Maiduguri metropolis.
Digital Terrain Model (DTM) generated from the Shuttle Raddar Topography
Mission was used to provide the basis for the terrain analysis to generate
hydrological parameters such as elevation, flow accumulation and direction,
drainage network and slope angle as well as classified elevation images and
terrain wetness index to map out potential flood risk areas. The DTM identified
potential areas liable to flash flood and inundation. The 3D Digital Terrain
Model (DTM) of the area showed where potential floods or traps were located in
the metropolis. The findings further revealed that Maiduguri was generally
characterized by low lying locations with slope angles of less than 5 degrees
covering an area of 144.4 km2 out
of 148 km2 making it
extremely difficult to drain. The processed flow accumulation of the study area
showed a high flow accumulation pixel value of 19,972 that drained into outlet,
suggesting that a large proportion of the study area was getting flooded during
a rainstorm. Even though the calculated drainage density of 0.73 for the study
area indicated a very good drainage system, this was also undermined by the
flat terrain and urbanization. The study recommends for improved land use
planning; raising awareness of the residents, provision of more drainages and
continued vulnerability mapping improved the functionality of bodies
responsible for flood management among others for sustainable flood management
in the study area.