URBAN FLOOD RISK MANAGEMENT: A CASE STUDY OF ABOABO, KUMASI

ABSTRACT
Floods are a serious global issue attracting attention and research from academia, the media and other international discourse. Consequently, they have become critical national issues especially with African countries who lack the financial resources and technical knowhow to mitigate its impacts. The Aboabo community (a suburb of Kumasi), located in the transitional forest zone of Ghana has become vulnerable to the devastating effects of flooding in recent times due to climate change, exponential population growth, and rapid urbanization. In order to reverse this trend and lessen the debilitating impacts of flooding on this community, there is a need for the development of a flood risk map which will form the basis of any future flood management and planning activities. This study presented a holistic approach in the development of a flood risk map and discusses its significance in Flood Risk Management.
In order to create a digital representation of the study area, a Digital Elevation Model (DEM) was created. Hydrological analysis necessary to determine flow direction and accumulated flow (resulting from e.g. rainfall, surrounding streams) was performed on the depressionless DEM of the study area. Reclassified slope angles (i.e. high slope areas, medium slope areas, and low slope areas) and stream buffer zones (within 50m of stream network) were added in ArcGIS environment to generate flood risk maps. The flood risk maps showed three risk zones -High risk, medium risk zone and low risk zone. To further demonstrate the potential of flooding in these three risk zones, a simulation-based approach was adopted. A simple vector-based method which only required the extents of flood levels in simulating flood extent based on the derived drainage lines, their depth and their capacity to hold rainfall run-off was used. With the aid of the elevation measure, flood water levels were selected. The flood contours showed the extent of flood at a given flood level. The flood model extents were further overlaid on a geo-referenced Google Earth image of the study area which visibly demonstrated areas at risk in the event of floods. Based on existing literature, questionnaires and interviews were administered to respondents in the Community and stakeholders to investigate the causes and effects of floods. With over 84% response rates, majority of the residents attributed the cause and effect of flooding to lack of drains/choked drains and gradual weakening of buildings respectively.

The research clearly demonstrated the application of GIS through hydrological analysis, carrying out flood simulations and the administering of questionnaires and interviews with stakeholders, is very essential in providing guidelines for Flood Risk Mapping.


CHAPTER ONE
1.0 INTRODUCTION
1.1 Background
The effects of climate change are shown to have immensely affected the changing weather conditions in many parts of the world. There is a global concern about global warming. Global warming is leading to climate change as noted in the third assessment report of the Intergovernmental Panel on Climate Change (IPCC, 2001). Global warming has caused incidences of tsunamis, melting of iceberg, washing away of shorelines, flooding and drowning of islands (IPCC, 2001).Consequently, flooding has become of great interest to humanity (Oppong, 2011). Floods claim approximately 20,000 lives annually, leaving people homeless in the process and have negative implications on at least 20 million people all over the world (Smith, 2011).

Floods have claimed over 10,000 lives in the United States of America since 1900 (Adeoye et al., 2009). Statistics also show in 1998, floods affected approximately 30 million people in 52 out of 64 districts in Bangladesh mainly as a result of climate change and economic growth in low-lying regions (Khan et al, 2011).

In July and August, 2010, Pakistan was hit by one of the worst floods in their history of disasters rendering 20 million people homeless (Straatsma et al, 2010).

Over 22,000 people in Nepal had to relocate temporarily due to floods. It further stated 46,000 houses were left totally damaged and more than 130,000 hectares of agricultural lands were submerged by floods (Asian Development Bank, 2007).

In 2011, Thailand also experienced heavy rains that lasted nearly 12 weeks claiming over 500 lives in the process. All these reports and studies, illustrates the devastating effects of floods (Orok, 2011).

Floods are crucial national issue as a great number of African countries lack the resources, both financially and technologically, to fight the effects and impacts of flooding (Satterthwaite et al., 2007).

Between 1996 and 2005, floods have posed several devastating and terrifying effects on the continent of Africa (Satterthwaite et al., 2007).. Within that period, there were approximately 290 flood-disasters reported. Over 8,183 people lost their lives, approximately 23 million people were consequently affected in diverse ways. The results of the huge economic losses were estimated at approximately $1.9 billion (Satterthwaite et al., 2007).

Flooding is one of the leading disasters in Ghana and has major impacts on people and their livelihoods. The period between 1968 and 2011, incidences of flooding have killed approximately three hundred people leaving over 3 million people affected (Okyere et al., 2012). Flooding also comes with an increase in epidemics especially through the spread of waste, flood water and the accumulation of water and consequent blockage tends to be conducive breeding grounds for mosquitoes (Feng et al., 2007; Messner et al., 2007).

Among the various types of land use/cover, urban areas have the greatest tendency of modifying the hydrological behaviour of a catchment. The construction industry (roads, buildings, etc) accompanying urbanisation creates impermeable surfaces impeding infiltration of water and lead to overland flow leaving urban areas highly susceptible to floods (flash floods) especially when there are bad drainage network systems (Okyere et al, 2012).

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Item Type: Ghanaian Project Material  |  Attribute: 112 pages  |  Chapters: 1-5
Format: MS Word  |  Price: GH50  |  Delivery: Within 30Mins.
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