Available records show that the frequency and magnitude of the occurrence of floods across Nigeria have more than doubled in recent years. Flood is a common physical problem particularly across Nigeria’s coastal areas. The recent increased incidence of floods can be attributed to sea level rise, increased storm frequency and intensity all related to climate change. These factors are worsened by such local factors as the growing occupation of floodplains, increased runoff from hard surfaces, inadequate solid waste management and silted-up drainage. In this post, we examine the possible impact of climate change on flood events in Nigeria. Considering the damage flood often impose on the environment, there is the need for government and other stakeholders to act to alleviate flooding and its causes, especially the consequences of climate change.
Flood is an extreme weather event marked by overflowing or irruption of a great body of water over land not usually submerged.
The current high incidence of floods witnessed across Nigeria has been attributed to increased storm frequency and intensity, melting of polar ice caps and rise in sea level. The rise in sea levels has led to salt water intrusion of coastal lands.
Flood appears to be the most common environmental hazard and usually claims many lives per year in various locations across Nigeria.
Across the country, especially in the coastal areas, floods have posed tremendous danger to people’s lives and properties.
In recent times, hundreds of people in Nigeria were killed when the combination of high tides and heavy downpour caused widespread flooding of the low-lying delta region of the country.
Researchers have examined the factors responsible for floods in Nigeria. Some of these factors include sea level rise, heavy rainfall, poor drainage systems and blocked drainage channels.
In most cases, a combination of these factors interacts to cause the worst flooding.
Particularly, urban flooding has become incessant in most Nigerian cities. The incidence has more than doubled in recent times mainly because the increase in urban population has compelled more people to build houses along riverbeds and floodplains.
Climate change is worsening the problem of urban and coastal floods because of the increased likelihood of more intense and frequent rain storms.
Already, the Niger Delta region of Nigeria is experiencing steady increase in rainfall intensity, perhaps as a climate change impact in the country.
Furthermore, it is projected that rainfall intensity will increase the more in the future, possibly by as much as 10-20% by the end of the century.
In Nigeria, floods and drought are either directly or indirectly responsible for almost 90% of damages relating to natural disasters.
Hundreds of thousands have been rendered homeless as a result of devastating floods across the country.
Floods in various parts of Nigeria have forced thousands of people from their homes, destroyed businesses, polluted water resources and increased the risk of diseases.
Forms of Floods in Nigeria
Floods occur in Nigeria in three major forms:
Coastal Flooding: This occurs in the low-lying region found along the coast.
River flooding: This occurs when sudden, heavy rains change rivers in the inland into destructive torrents within a short period.
Urban flooding: This occurs in urban centers, on flat or low-lying terrain especially where surface drainage is poor or non-existent; or the drainage has been blocked with municipal waste and refuse.
Nigeria is vulnerable to climate change impacts due to its geography, climate, vegetation, agricultural activities, economic nature, population and settlement, and energy demands.
Nigeria’s location, size, and relief give rise to a variety of climates ranging from rainforest along the coastal and southern zone to the Sahel in the north eastern section of the country.
Nigeria has a population of about 200 million who impact on the physical environment through their various activities.
More than sixty-five per cent of the people are farmers, cattle rearers and fishermen while the informal sector constitutes the bulk of the urban population’s economic activities.
In recent years, rainfall intensity across the country has increased with associated floods in the coastal towns while drought still prevails in the northern part of the country.
These differences in distribution in rainfall amount and consequent impacts on water resources, human settlements, among others, are indicators determining the vulnerability of the coastal areas of the country to climate-induced floods.
Globally, gradual temperature rise and sea level rise provide strong evidence of ongoing climate change. Current scientific opinion is that a process of anthropogenically-forced global climate change is under way, over and above normal background climatic variability.
Climatic parameters are changing and might change more in future with potential impacts. Data shows that average surface temperatures across Nigeria has risen by about 1.4°C, causing an increase in flood hazard in some areas because of sea level rise, changes in seasonal rainfall.
Climate change is making rains more uncertain and heavy storm rainfalls more likely. The unpredictability of rainfall is manifesting as much more frequent storms producing floods in many cities across Nigeria.
Climate change works in an indirect way to worsen urban flooding in Nigeria and other countries in Africa.
Floods in rural areas, such as the major floods in Niger Delta, have forced many rural people to move to towns, adding large new populations to existing slum communities.
Climate change compounds the existing challenges of managing floods.
First, the recorded sea level rise could have a major impact on flood risks in the coastal cities. Second, increases in the frequency or intensity of extreme rainfall events worsen risks of disastrous flooding in coastal areas across the country.
Researchers are of the opinion that climate change has contributed to the increased frequency of flooding in Nigeria. Some flood control measures (including land use control, demolition of illegal structures, stopping indiscriminate dumping of refuse in the drainage system, mapping of the flood prone area) can only solve the problems of flooding which are man-made, and mostly at the hinterlands. However, climate-induced floods occur mainly in parts of Nigeria situated in low-lying areas, which can be submerged during heavy rains. Researchers are of the opinion that there is the need to reduce greenhouse gas emission in order to avoid the worst impacts of climate-induced floods in the country.
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