Flooding is an overflowing of water onto land that is normally dry, which can happen during heavy rains, when ocean waves come on shore, when snow melts quickly, or when dams or levees break. Damaging flooding may happen with only a few inches of water, covering a house to the rooftop. Floods can occur within minutes or over a long period, and may last for days, weeks, or longer. They are the most common and widespread of all weather-related natural disasters.
Flash floods are the most dangerous kind of floods, because they combine the destructive power of a flood with incredible speed. They can happen within minutes of the causative rainfall, limiting the time available to warn and protect the public.
History of Flooding in Nigeria
Nigeria has witnessed a long history of flood disasters, dated back to 20th century. However, the frequency and intensity of floods have increased in recent decades, primarily due to climate change and poor urban planning. The 2012 episode which affected over 30 of Nigeria’s 36 states, leading to the displacement of about two million people and the death of over 363 individuals, remains of the most devastating floods known to Nigeria.
As many states across the federation activate their flood response mechanisms, causes of flooding deserve a cursory examination. Globally, flood disaster is traceable to many natural and human factors including rainfall, river overflow, topography and climate change as well as poor urban planning, deforestation, dam failure, soil erosion and blocked drainage systems among others.
The main causes of flooding in Nigeria, according to the experts, include lack of infrastructure, poor urban planning and governance, housing development in flood-prone areas, deforestation, haphazard developments leading to the blockage of drains, poor waste disposal practices, negligence by the government in designing and implementing policies, as well as weak enforcement of policies and laws. In the Niger Delta Region, the construction of dams and upstream land use has been identified as reducing river discharges, and leading to flooding. Climate change impacts such as increased rainfall intensity, frequency, and duration, has also been recognized as a driver of flooding in Nigeria.
Nigeria experiences heavy and prolonged rainfall, especially during the rainy season. This, coupled with inadequate preparedness for disaster can overwhelm the existing drainage systems and cause rivers to overflow their banks. This results in flooding. River Overflow is another major cause as witnessed in recent years. Heavy and prolonged rainfall get major rivers like the Niger and Benue to overflow, causing widespread flooding in adjacent areas.
Talking about topography, certain areas in Nigeria are low-lying and naturally prone to flooding. Coastal regions and floodplains are particularly vulnerable. The 853km long Nigeria coastline runs through seven of the southern states of the federation including Lagos, Ondo, Delta, Bayelsa, Rivers, Akwa Ibom and Cross Rivers bordering the Atlantic Ocean.
Perhaps the biggest culprit is climate change; increasing global temperatures are leading to more intense and unpredictable weather patterns, including heavier rainfall and rising sea levels, which contribute to flooding. Climate change also makes connecting extreme weather events more likely as stronger heat and dry conditions result in parched soils. Parched soils increase the risk of flash flooding when it rains.
Besides the natural causes of flooding, one of the commonest anthropogenic (human) causes is poor urban planning. Rapid urbanization without adequate planning leads to the construction of buildings in flood-prone areas. Lack of proper drainage systems exacerbates the problem. Urbanization which is responsible for the construction of impervious surfaces like concrete, asphalt, and buildings, reduces the ability of the land to absorb water. Instead, water runs off the surface quickly, often overloading drainage systems and leading to flooding.
Tree cutting (deforestation) for whatever purposes whether agriculture, logging, and urban development, also reduces the land’s ability to absorb rainfall, increasing surface runoff and the likelihood of flooding. According to Emission Index, forests absorb and disperse heavy rain, reducing its force and volume. Therefore, absence of tree cover removes this natural barrier and makes the ground less able to soak up water, leading to more runoff in water bodies.
Blocked Drainage Systems result most often from improper waste disposal and lack of maintenance. A clogged drain can cause water leaks, slow water draining, collapsed drains and even burst pipes, leading to flooding within minutes. Close to this is poorly maintained dams, which can break or overflow, releasing large volumes of water downstream and causing sudden floods.
Soil erosion, which is becoming a growing national concern, can also cause erosion. Soil erosion is a product of unwholesome human activities like mining and farming without proper soil conservation measures. Eroded soil can fill up riverbeds, reducing their capacity to hold water and leading to overflow during heavy rains.
Destructive Impacts of Flooding
Flooding in Nigeria has far-reaching impacts, affecting various sectors of its economy. Floods result in the loss of lives and contribute to the spread of waterborne diseases such as cholera and typhoid. The World Health Organization (WHO) enumerates some of the effects on health.
Homes, roads, bridges, and other infrastructure are often damaged or destroyed, leading to significant economic losses. In 2018, the Nigerian Hydrological Services Agency reported that the country lost over N1.9 trillion due to flood-related damages.
Agriculture and food production is equally compromised by flooding as the deluge inundate farmlands, destroying crops and livestock, which leads to food shortages and increased prices.
During flood disaster, thousands of people are displaced annually, leading to humanitarian crises. In 2022, floods displaced over 1.4 million people across the country.
Climate experts have predicted that the frequency and intensity of floods in Nigeria may continue to increase in 2024 due to ongoing climate change effects. The Nigerian Meteorological Agency (NIMET) has warned that states along the River Niger and River Benue, as well as coastal regions, should prepare for severe flooding during the rainy season. According to NIMET’s Director-General, Prof. Mansur Matazu,“with the current climate trends, we anticipate a high likelihood of intense rainfall and subsequent flooding in various regions of the country.”
Containment Measures
Addressing the flood menace in Nigeria requires a multi-faceted approach. One of the solutions which must be spare-headed by the government is improved urban planning. Authorities need to enforce stricter building codes and ensure proper drainage systems are in place to prevent urban flooding.
There is the need to improve the efficiency of our early warning systems. Enhancing meteorological and hydrological monitoring systems can provide early warnings to communities at risk, allowing for timely evacuations and preparations.
Since deforestation is one of the causes of flooding, reforestation and afforestation must be taken seriously at all levels of government and at the community level. Urban forestry must be strongly considered for the nation’s urbanized cities as tree planting and restoring natural vegetation can reduce surface runoff and enhance groundwater recharge.
Experts have for the umpteenth time recommended regular dredging of rivers and proper management of dams to prevent overflow during heavy rains. Government at all levels must consider this ahead of the 2024 flood disaster season.
Lastly, public awareness campaigns on flood risks and preparedness should be mounted across the country to put communities on red alert for impending flooding and to empower them to take proactive measures to reduce losses associated with such disaster.
This piece first featured on Radio Nigeria climate change series of June 28,2024, as a contribution towards increased awareness about climate change and to foster a better understanding of this pressing global issue.
Alfred Ajayi is journalist, writer, climate change enthusiast.
Nwacto
About The Author
