FLOOD RISK MANAGEMENT IN GHANA: A CASE STUDY OF ACCRA SAMUEL ASUMADU-SARKODIE Sustainable Water Resources (SEES-503) Term Paper Presentation METU NCC

Outline Introduction Problem Statement Justification Research Objectives Critical Analysis Proposal Conclusion Recommendations References

Source: Google Earth, 2014

Source: MOE, 2012

Introduction Several natural disasters have occurred since the time of biblical Noah up till now. These natural disasters have taken various forms such as; flooding, earthquake, volcanic eruption tsunamis, tornadoes, landslides, hurricane, among others. Flooding was defined by Hague: 1997 as “a natural hazard which displaces people by destroying their land, houses and other tangible goods and assets” [2]

Problem Statement Within the last decades, Accra has experienced periodic floods. Between 1955 and 1997, about GH¢300 billion worth of properties has been destroyed, 100 lives have been lost either during the flood period or after the floods and 10,000 people have been displaced from their homes [8]. Against this background, the research seems necessary.

Justification The Government of Ghana has signed a contract (US$ 660 million) with the Conti Group of Companies from the USA on a five year project to tackle the flooding situation in Accra [7].

Research Objectives To assess the natural and manmade activities that causes flood in Accra. To examine suitable structural measures that can be to undertaken to reduce and manage flood impacts in Accra. Propose a mitigation approach to manage flood impacts using Integrated Urban Flood Risk Management for The 21st Century.

Natural Disaster in Ghana from 1900 to 2014 Total Affected (persons) № of Events Killed Total Affected (persons) Damage (US$) Drought 3 - 12,512,000 100,000 Flood 17 409 3,884,990 780,500,000 Epidemic 19 875 33,799 Wildfire 1 4 1500 Earthquake ECONOMIC IMPACT OF FLOODING SHOWED IN THE FIGURE Source: EM-DAT: The OFDA/CRED International Disaster (Adapted)

Profile of the Study Area Accra is the capital city of Ghana Population: 2 million Land mass: 1,261km2 Source:

Drainage System & Characteristics 1 Accra consists of eight drainage basins with Characteristics of lowlands, and hilly areas that runs out into the sea. As a result of these basins, storm water runs out from the city through it.

Source: Waterworld, 2010

Drainage System & Characteristics 2 According to waterworld, the design capacity of these basins is based on a 25-year return period: which means that the maximum rainfall reoccurs in 25 years [3].

Drainage System & Characteristics 3 Over a period from 1970 – 2008, the average annual rainfall is 756 mm with about 0.954 km3/year as the total amount of rain that falls in Accra within one year with a rainfall intensity variations of 203 mm/h [6]. A rainfall intensity variations of 203 mm/h may or may not be reached for short periods of rainfall [23]

Early Warning Signs The Ghana Meteorological Service relays information to the Accra Metropolis through national television, local radio stations and newspapers to highlight impending storm that would hit the metropolis but unfortunately, the intensity and the extent of flash floods are always not predicted [6]. Unfortunately, Mechanisms of evacuation has never being implemented apart from the formal mechanisms of early warning signs through the media

Traditional Flood Management Possibilities There are a number of different ways to categorize such flood management interventions. These flood management interventions can be either structural or non-structural; physical and institutional; implemented before, during and after the flood and these categories are interwoven [2]. Conventionally, management of floods in Accra management has in essence been a struggle for successive governments in Ghana as strategies to combat this havoc has being problematic: new flood projects are implemented after a severe flood. 2. Flood management practices have mostly concentrated on reducing flooding and decreasing the exposure to flood damage through a range of interventions.

What Are The Flood Issues In Accra???

Source: Guidelines for Planning Authorities: 2009 3.1 Erosion and Sedimentation  In Accra where roads are not tarred, gullies and erosion are evident on road surfaces and the soil between buildings as a result of this, floodwater is stopped from entering roadside drains where they are provided. Problems associated with reduced capacity as erosion results in a high delivery of sediments from some urbanized area around the catchment.   3.2 Improper Settlements Some buildings in certain towns in Accra are positioned close to rivers and drains, whilst others are built only a few meters away from the stream channel or even across natural watercourses which results in increasing the risk of these settlements to flooding. 3.3 Drainage Capacity  Current drains like the Korle Lagoon are often clogged with refuse and silt which results in reduced capacity of the river or stream channels leading to flooding.     3.4 Improper Waste Management Practices Improper waste management practices in Accra and the incidence of flooding in the city are correlated. 3.5 Urbanization  Increasing Urbanization and its related activities have impacted negatively on the drainage systems in Accra. Development of residential buildings and paved roads increases the impermeability of the catchment areas giving rise to quicker catchment response to rainfall and increased runoff. Source: Guidelines for Planning Authorities: 2009

Surcharge sewer leading to basement flooding

Improper settlements

Improper waste management leading to reduced drainage capacity

Research Analysis and Discussion Water run-off with the basins in Accra was deduced using the modified rational model by Viessman & Lewis, 1996; and Mannaerts, 1996 to calculate individual discharge for each section in the entire catchment areas. i.e. Qp= 0.278×Cs×C×i×A A secondary data on the size of the basins in Accra, the run-off coefficient, storage coefficient and the rainfall intensity was derived from Ghana Meteorological service. From these data. Water run-off with the basins in Accra was deduced using the modified rational model by Viessman & Lewis, 1996; and Mannaerts, 1996 to calculate individual discharge for each section in the entire catchment areas. I.e. Qp= 0.278×Cs×C×i×A [33], [34] In the calculation of the discharge of each basin, the formula below was employed; Qp= 0.278×Cs×C×i×A [33], [34] Where: Qp= run-off rate (m3/s), C= Run-off Co-efficient, Cs= Storage Coefficient, i= Rainfall Intensity (mm/hr) and A= Area of Drainage (Km2) Run-off coefficient of urban areas ranges between 0.7 and 0.95.

Research Analysis and Discussion 3 From the figure above, it can be deduced that as the area increases, peak discharge also increases. This is because, large drainage basins catches more precipitation so have a higher peak discharge compared to smaller basins. Smaller basins generally have shorter lag time because precipitation does not have as far distance to travel. This is the reason why Middle Sakumo basin continues to experience that highest floods in Accra. As a result of increased urbanization, the drainage basins, the run-off coefficient, as well as the peak run-off will increase

Research Analysis and Discussion 2 In Ghana, raining season starts from April and ends in July with heavy rainfall and thunderstorms mostly in May. High rainfall intensities can have an effect on the storm hydrograph. Heavy storms result in more water entering the drainage basin which results in a higher discharge leading to flood over a long period of time.

Integrated Flood Risk Management Approach 1 Global Water Partnership (GWP), defines Integrated Water Resources Management as ‘a process which promotes the coordinated management and development of water, land and related resources, in order to maximize the resultant economic and social welfare in an equitable manner without compromising the sustainability of vital ecosystems’ [4]

Integrated Flood Risk Management Approach 2 An Integrated Flood Management plan should address the following six key elements that follow logically for managing floods in the context of an IWRM approach: • Manage the water cycle as a whole; • Integrate land and water management; • Manage risk and uncertainty; • Adopt a best mix of strategies; • Ensure a participatory approach; and • Adopt integrated hazard management approaches. IN OTHER WORDS, ANY FLOOD MANAGEMENT PROJECT WITOUT THE INTEGRATED FLOOD RISK MANAGEMENT APPROACH LACKS MERIT.

Integrated Flood Risk Management Model Integrated Flood Management Water Resource Management Hazard Management Costal Zone Management Land Use Management Source: Adapted from WMO: 2006

Strategies And Options For Flood Management

Dikes, levees and flood embankments High flow diversions STRATEGY OPTIONS Reducing Flooding Dams and reservoirs Dikes, levees and flood embankments High flow diversions Catchment management Channel improvements Reducing susceptibility to Damage Floodplain regulation Development and redevelopment policies Design and location of facilities Housing and building codes Flood proofing Flood forecasting and warning Mitigating the impacts of flooding Information and education Disaster preparedness Post-flood recovery Flood insurance Preserving the Natural Resources of Flood Plains Floodplain zoning and regulation integrated flood risk management interventions incorporates a combination of structural and non-structural; physical and institutional; and these must be implemented before, during and after the flood. Source: Adapted from WMO: 2006

Conclusion Flooding as a natural disaster cannot be eradicated in Accra but however, its effect can be minimized by undertaking the Integrated Flood Management approach which promotes the coordinated management and development of water, land and related resources, in order to maximize the resultant economic and social welfare in an equitable manner without compromising the sustainability of vital ecosystems.

Recommendations There should be improved collection of waste and disposal, de-silting gutters, river channels, and culverts that are frequently taken up by solid waste to improve the hydraulic performance of drains and increase carrying capacities in order to reduce peak discharge. There should be an enforcement of building regulations that prevent people from building in flood prone areas and floodplains to avoid flooding.

References EM-DAT: The OFDA/CRED International Disaster Database, www.emdat.be - Université catholique de Louvain - Brussels – Belgium Waterworld (2010). Stormwater solutions in Ghana. Article published in the Ghanaian Times: http://www.waterworld.com/articles/2011/09/stormwater-solutions.html. Accessed on: 24th October, 2014. SWITCH Accra City Story (2008). http://www.waterworld.com/articles/2011/09/stormwater-solutions.html. Accessed on: 24th October, 2014. Global Water Partnership, 2000. Integrated Water Resources Management. Global Water Partnership (GWP), Technical Advisory Committee (TAC). World Meteorological Organization, 2006a: Legal and Institutional Aspects of Integrated Flood Management. Associated Programme on Flood Management (APFM) Technical Document No. 2, Flood Management Policy Series, (WMO-No. 997), Geneva. Available At: http://www.apfm.info/pdf/ifm_legal_aspects.pdf. Accessed on: 27th October, 2014

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