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Nigeria’s Landslide Challenges

News reports from September 2023 indicated that an estimated 30 people lost their lives in a landslide within Nigeria's capital city. This incident was allegedly linked to illegal mining activities. Landslides are a frequent occurrence in Nigeria, and despite efforts through various studies to reduce their impact, predicting and mapping susceptible areas remains a challenge. This difficulty arises from a lack of comprehensive data on local landslide occurrences and slope instability issues, compounded by the absence of a systematic database documenting past landslides.


A landslide is a geological phenomenon involving the movement of rock, soil, and debris down a slope. Numerous things, such as intense rain, earthquakes, volcanic activity, human activity, or modifications to the slope material's composition, might cause landslides.


Landslides take place across diverse regions worldwide, spanning various climatic conditions and environments. Furthermore, any steep terrain including cliffs, mountains, and slopes can experience landslides. As a natural hazard, landslides have become a growing global concern each year in numerous parts of the world, resulting in catastrophic consequences, causing monetary losses amounting to millions of dollars and accounting for thousands of deaths and injuries annually. The major triggering factors include both natural and human activities. The natural triggering factors include precipitation and slope instability, while the activities that influences landslides includes construction, mining, quarrying and excavations.


While landslides can happen globally, their causes, consequences, and mitigation strategies are typically influenced by the geological, hydrogeological, and geomorphological characteristics of the specific location. Therefore, the risks associated with landslides varies by area, emphasizing the need for region-specific mitigation techniques. In Nigeria, landslides are widespread in many parts of Nigeria during periods of heavy rainfall and are triggered by water infiltration in slopes with high gradients. (Igwe, 2015).


There are various types of Landslides and they are classified according to the type of rock movement. They include; Falls, Topples and Flows.


Figure 1 (A-C): Figure showing Rockfalls, topples and Flows


Landslides in Nigeria

Although Landslides can be found in virtually every state in Nigeria, it is prevalent in the southern part of the country (as shown in the map in Figure 2 below) and are influenced by both natural and human factors.



Map of Nigeria showing states where landslides have occurred in Nigeria
Figure 2: Map of Nigeria showing states where landslides have occurred in Nigeria (Agbor et al., 2014).

General Factors affecting Landslide Occurrence in Southern Nigeria

Generally, the factors affecting landslides in Nigeria (according to appraisal of landslides in Southern Nigeria by C.O Okagbue) are:


  • Topography: Since many of the large landslides in southern Nigeria have historically occurred along steep slopes connected to cuestas, ridges, uplands, and other types of slopes, topography can be thought to play a significant role in the occurrence of landslides. For instance, the Akovolwo hills near Jato Aka in Benue State, the portion of the Enugu-Awgu escarpment at Isuawa in Anambra State, the hills at Ikom in Cross River State, the Gwolawo and Ogbajala hills in Idab, Benue State, and the peaks near lie-Ife in Oyo State have all had significant landslides in recent years.


  • Hydrologic Conditions and Climate: The majority of slope shifts in southern Nigeria are a result of climatic and hydrologic factors. First, the intense weathering and other physical or chemical processes in the soils and rocks are favoured by the climatic (humid tropical) shifts from the rainy to the dry season, which weakens the soils and rocks. Increases in pore water pressure are caused by the hydrologic circumstances of extremely wet soils and elevated groundwater levels during the rainy season. Because of this, the majority of landslides happen during the rainy season, when the soils become more or less saturated and less resistant to shear.


  • Human Activities: Landslides result from increasing shear stress on slopes, which is frequently caused by human activity. Shear stress can be raised by erecting structures, stockpiling rock and garbage, cutting down slopes, creating quarries and pits, and surcharging slopes through filling. Road cuttings were in fact the cause of a number of landslides that occurred along the Enugu/Onitsha express road, the Ninth Mile Corner/Nsukka new road, and the Enugu-Port Harcourt express road (Ulakpa et al., 2020). The rocks in these cuts are subject to weathering, which weakens their shear strength, and erosion, which causes many of them to become over steeped. Additionally, many slopes' hydrologic conditions have changed as a result of vegetation cutting for farming, which has encouraged rapid runoff and erosion that has resulted in landslides and debris flows.


Impact of Landslides

Landslides (and gully erosion) in Nigeria have been responsible for widespread destruction of transportation and communication systems, degradation of arable land, contamination of water supply, isolation of settlements and migration of communities. Also, when landslides occur in both urban and rural communities underlied by major aquifers, there’s absence of suitable portable water supply systems. All of these are seen commonly in Southeastern Nigeria as shown in Figure 3 & 4 below




Pictures showing areas affected by landslide in Anambra and Cross River respectively in South-Eastern Nigeria
Figure 3 & 4: Pictures showing areas affected by landslide in Anambra and Cross River respectively in South-Eastern Nigeria

Mitigation of Landslides

Due the enormous damages caused by landslides globally, research and governmental institutions have for a long time attempted to reduce damages caused by landslides (Yalcin 2007). Accordingly, the federal Government of Nigeria has spent huge amounts of naira in recent times in order to repair damages and mitigate future occurrences of landslides. For Example, according to Dataphyte.com, the Nigeria government budgeted a total of 64.417 billion naira for ecological funds between 2021 and 2022.

Various journals studying landslides in Nigeria have been written based on various studies carried out in the South Eastern Nigeria (Igwe and Una, 2019, Egboka et al), has shown that combating landslides requires a multi-pronged approach. Firstly, adopting sustainable land management practices is crucial. This includes avoiding activities like topsoil removal, overgrazing, continuous cropping without rotation, improper waste disposal, and obstructing drainage systems. These practices reduce the soil's moisture content, impacting its shear and slope stability, ultimately leading to gully formation.


Secondly, raising public awareness, particularly in affected areas, is vital. Governments, NGOs, and community leaders must educate the public on the importance of sustainable farming and land use practices that minimize the risk of gully erosion


Furthermore, implementing stricter regulations through construction and building codes is essential. Additionally, thorough mapping of the area to identify hazard zones is necessary. These maps will guide developers and builders to construct structures that effectively combat erosion. Finally, conducting thorough Environmental Impact Assessments (EIA) before any infrastructure development is paramount to prevent the creation of new erosion features.


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