Torrential rain in northern and central Nigeria has coincided with high river levels to exacerbate the flood risk in the states of Kano, Nasarawa and Niger.
The flooding appears in part attributed to heavy rainfall within neighbouring countries of Nigeria and those that lie within the Niger river basin. Niger experienced heavy rainfall earlier in the month with several states affected by localised flooding in July and August 2018. Based on the Niamey gauge station (Niger), water levels had increased from 1.47m to 5.38m from 28 June to 15 August (Niger Basin Authority). As of mid-August, this rainfall had resulted in 19 deaths and at least 65,000 people affected by the floods. In addition, 7,000 houses, 25,000 livestock and 6,500 hectares of crops were destroyed (Floodlist).
Pictured Above: Illustration of states affected by the floods in Nigeria as of August 2018. The flooding has been caused by flows upstream of the Niger River. As the water level in the Niger River near Kogi continues to rise, flood warnings have been issued for Kebbi, Kwara, Kogi, Anambra, Delta and Bayelsa states. JBA Nigeria River Flood Map (200-Year Return Period) is provided for context (JBA Risk Management Limited TM).
The more recent flooding in Nigeria has coincided with localised rainfall and the antecedent high river discharges of the Niger river. Flooding has been reported in the Nigerian states of Kano, Nasarawa and Niger, with the levels equal or higher as those seen in the October 2012 floods in Nigeria, which still linger long in the memory of many Nigerians (Floodlist).
Pictured Above: Estimated rainfall across Nigeria measured in millimetres (mm). The darkest shade of blue seen on the map represents 30mm of rainfall over a day and white represents 0mm. The affected states are highlighted in orange. These states received some rainfall before 27 August 2018. Continuous and heavy rainfall on 27 August 2018 resulted in flooding in Kano, whereas rainfall between 28–29 August 2018 triggered flooding in Niger and Nassarawa. (Data Source: NASA EOSDIS Worldview; GES DISC – AIRS2UP_NRT: AIRS/Aqua L Near Real Time Support Retrieval V006; GES DISC – Near Real Time Data).
Comparisons to 2012
On 29 August 2012, water heights of 8.57m were recorded at Lokoja (a confluence of the Niger and Benue Rivers) (Nigerian Hydrological Services Agency). The same gauge recorded 8.69m on 29 August 2018 which has created alarm among authorities and citizens. However, despite the recent river levels, flood damage has not been on par with 2012.
The Niger River basin is a large and highly complex network of rivers which encompasses nine countries: Benin, Burkina Faso, Cameroon, Chad, Ivory Coast, Guinea, Mali, Niger and Nigeria. In Nigeria, the Niger Delta contributes up to 8% of the land area.
In 2012, heavy rainfall occurred throughout the month of September causing high volumes of water to be held back in dam reservoirs. At the end of September, as these dams were forced to open, the high volume of water could no longer be contained, resulting in extensive floods across floodplains of the Niger and Benue rivers. This resulted in extensive economic losses and damage to properties and infrastructure. For instance, flooding in the Niger Delta disrupted oil production and damaged many hectares of crops (Reuters, 2012). Towards the end of October 2012, more than 2 million people had been displaced, 450 lives were lost and 400,000 houses were damaged (Swiss Re). In total, 30 out of 37 states were affected including Lagos, the capital city. It was reported by Swiss Re that the event incurred USD $440 million in losses and only 2.3% were insured for (Swiss Re). Other countries in the Niger basin were not spared the damage as 519,000 people were affected in Chad and more than 250,000 hectares of croplands were inundated (Reliefweb).
Lessons Learnt
As flooding occurs frequently along the Niger and Benue Rivers, the large population situated along the river is at high risk. High rainfall, poor urban planning, inadequate drainage systems and a lack of advanced technologies to monitor and mitigate flood are common reasons cited for flooding in African cities (World Bank Group). These urbanised cities were developed rapidly, incurring the loss of natural soils as land areas were replaced by roads and buildings. Unregulated housing in flood prone areas has significantly contributed to the flood risk (World Bank Group).
Thankfully, the government understands the increasing need for improved flood management in Nigeria, as noted during the 2013 floods in Nigeria. During this event, approximately 22,000 volunteers were trained by the Nigerian Red Cross for post-event response. The warehouses were also stocked with necessities in preparation for future emergencies. In addition, dam officials were advised to release water from the dams periodically to reduce the risk of flooding for communities downstream (The Guardian, 2013).
Outlook
To the countless villages, towns and cities that lie alongside its banks, the August 2018 flooding is a reminder of the perennial risk that the Niger River basin poses to both Nigeria and other neighbouring countries. One aspect that may mitigate the impact of this risk in future is the increased capacity and resilience of the emergency responders in Nigeria to manage these floods – many of whom were not in place in 2012.
JBA Risk Management has nationwide return period flood maps for Nigeria at 30m resolution. Please contact us for further information.
References
Brock, J., 2012, 'Nigeria Floods Kill 363 People, Displace 2.1 million', Reuters, viewed 6 September 2018
Davies, R., 2018, 'Niger- Floods and Rain Leave 19 Dead and 65,000 Affected', Floodlist, viewed 6 September 2018
Davies, R., 2018, 'Nigeria- Floods Hit Niger, Kano and Nasarawa States', Floodlist, viewed 6 September 2018
The Guardian, 2013, 'Nigeria Floods Test Government's Disaster Plans', viewed 6 September 2018
Jacobsen, M., Webster, M., Vairavamoorthy, K., 2013, ‘The Future of African Cities: Why Waste Water?’, The World Bank Group, viewed 6 September 2018
Nigeria Hydrological Services Agency, 2018, 'Update on NIHSA Early Flood Warning in Nigeria As At 30th August 2018', viewed 5 September 2018
ReliefWeb, 2012, 'Chad: Floods- August 2012', viewed 5 September 2018