DETERMINAnON OF FLOOD RISK ZONES IN ACCRA AND TEMA METROPOLIS

SSA Research BENJAMIN KOFI NYARKO 155 PAGES (25200 WORDS) Thesis
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ABSTRACT

Accra has been experiencing periodic flooding that affects properties and lives. For

instance on 41h and Sib June 1994, 8 persons lost their lives and 80 million cedis worth of

properties belonging to Paloma Company were destroyed due the floods that occurred at

that time. The government seeing the dangers involved. commissioned institutions such

as ~linistIy of Works and Housing, Tovm and Country Planning and City Engineers to

identify such areas and adopt measures that will help reduce the effect ofthis unexpected

extreme event The measures used by these institutions in order to identify and prevent

the occurrence of such extreme event have been woefully inadequate and inefficient

Hence this thesis examines new methods of identification of potential flood risk zones

stressing the possible combination of hydrological models with remote sensing and

geographic infonnation system models.

The main objective ofthe study is to determine flood risk zones in Accra and its environs

using a hydrological model and a geographical information system model. Specifically,

the study aims at assessing how the urban watershed has been modified in-terms of

drainage networking, soil texture. runoff and their influences on flooding. A flood risk

zones map and the paleogeomorphology ofthe study area were also constructed.

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Data for the study were from secondary and primary sources. The secondary sources

included rai.nfut~ discharge, and topography data, which were collected through literature

search from institutions such as Hydro Division of Ministry of Works and Housing,

Survey Department, Meteorological Service and \Vater Research Institute. The primary

data collected included drainage cros~ sectional measurement and soil characteristics.

These data were collected using field measurements. field observations. satellite image

interpretation and laboratory analyses.

The anaI~es ofthe data were based on the integration ofthe hydrological model into the

-Geographic Infonnation System model using an overlay operation.

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The result ofthe research showed that potential areas likely to experience periodic floods

with a given input of rainfall (140.2 mmlhour) are mostly below the 350-meter contour

and about 45 percent ofthe study areas fall \vithin flood risk zone. It was also noted that

the flood experienced by an area is mostly dependant on rainfall intensity no matter the

catchment area. However other factors such as, landuse, storage and runoff coefficient

were identified as contributory mctors to flooding in the study area..

In search for a method to detennine flood risk zones, the use of a hydrological model

within a geographic infonnation system model is very effective if only the appropriate

decision rule is defined. The studies will enable the supervisory agencies such as Ministry

of Works and Housing, Town and Country Planning and City Engineers enforce landuse

policies to prevent people from developing areas prone to floods.

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APA

SSA, R (2021). DETERMINAnON OF FLOOD RISK ZONES IN ACCRA AND TEMA METROPOLIS. Afribary.com: Retrieved April 23, 2021, from https://afribary.com/works/determinanon-of-flood-risk-zones-in-accra-and-tema-metropolis

MLA 8th

Research, SSA. "DETERMINAnON OF FLOOD RISK ZONES IN ACCRA AND TEMA METROPOLIS" Afribary.com. Afribary.com, 02 Apr. 2021, https://afribary.com/works/determinanon-of-flood-risk-zones-in-accra-and-tema-metropolis . Accessed 23 Apr. 2021.

MLA7

Research, SSA. "DETERMINAnON OF FLOOD RISK ZONES IN ACCRA AND TEMA METROPOLIS". Afribary.com, Afribary.com, 02 Apr. 2021. Web. 23 Apr. 2021. < https://afribary.com/works/determinanon-of-flood-risk-zones-in-accra-and-tema-metropolis >.

Chicago

Research, SSA. "DETERMINAnON OF FLOOD RISK ZONES IN ACCRA AND TEMA METROPOLIS" Afribary.com (2021). Accessed April 23, 2021. https://afribary.com/works/determinanon-of-flood-risk-zones-in-accra-and-tema-metropolis