Youths for Public Safety By Abubakar Jimoh
This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Over the years, landslides have remained one of the major threats to human life, property facilities, infrastructure and natural environment in most parts of Nigeria.
A landslide is a phenomenon arising from the rapid movement of large amount of soil mass over an extensive area which can cause serious damage to people and the environment such as agricultural farms, houses, roads etc. It could cut off water and power, block a road, or create many unpleasant conditions.
In December 2005 landslides in Umuchiani community of Anambra state led to the displacement of about 250 families; while over 20 communities in Awgu and Oji-River Local Government Areas of Enugu State were thrown into serious difficulties by landslides which cut off a portion of the Awgu-Achi-Oji River road in October 2011.
Several causes have been attributed to landslides, among which are climate change, intensified anthropogenic activities, growing urbanization, uncontrolled land-use, land clearance for agricultural practices, mining, stone quarrying, logging, deforestation, over-loading slope or blocking drainage by artificial fills or embankments; massive excavations, among others.
Meanwhile, with the amplifying level of landslides’ hazards and risks across the country coupled with the needs to manage the risks and protect the lives and property of Nigerians from the potential dangers of landslides, the National Emergency Management (NEMA) apart from its collaboration with Nigerian Geological Survey Agency (NGSA), through organization of conferences, workshops, training programmes in various parts of the country on Disaster Risks Reduction (DRR) has proffered valuable recommendations to mitigate the incidence of landslides.
Thus, putting in place, proper land assessment to determine areas prone to landslides and advising on how best to make the right decision prior to the erection of structures. In the analyses of geologists, the susceptibility of a given area to landslides can be determined and depicted using hazard zonation and preparation of landslide hazard map as tools to help identify land areas best suited for development by examining the potential risk of landslides.
The use of geological mapping will help in detecting slope hazards and determining the likelihood of landslide occurrence. In structural erections, geoscientists can assist engineers, developers, planners and building inspectors in avoiding high-risk areas. Through this process, structures such as homes, schools, hospitals, offices, power-lines, and roads can be safely located away from potential landslide risk areas.
Installation of drainage control or series of pipes that divert water away from unstable slopes is another option to mitigate occurrence of landslides. In this case, the surface drainage control works are implemented to control the movement of landslides accompanied by infiltration of rain water and spring flows. The drainage systems can be designed to channel the collected water out of the landslide zones as quickly as possible to avoid penetration of water that can cause damage to the area.
NEMA through its sensitization approaches as mentioned above has counselled slope prone communities on innovative mitigation techniques which include active slope monitoring systems, appropriate detective methods, early warning alert and innovative structures which have been found useful at some sites in various parts of the world. Such include improving surface or subsurface drainage, reducing the angle of the slope, excavating to unload the top of the slope, building protective beams to reduce erosion at the base of the slope, re-vegetation of the slope, and geotechnical nailing or artificial hard covers among others.
Besides, planting enough vegetation to strengthen and bind soil together contour trees on steep slopes will help to create stiff vegetation thereby serving as a barrier against slope. It has been observed that as these trees and shrubs grow, their roots will hold soil together, and help in reducing erosion of soil which is likely to result in landslides.
Before buying a home, check out for the sign of weak earth below the structure, and unstable walls. Get advice from a qualified geologist or geological engineer previous to the construction of your home; and request information and assistance from your municipal or district planner or building inspector while purchasing a land, sub-dividing, and construction applications. This helps to understand the environmental and safety regulations underneath the use of such structure or land.
Individuals are advised to cultivate total discipline towards the exploitation of natural environment as keeping environment safe from accumulated debris on a steep slope. It has been argued that small accumulations of debris can become flooded and hasty a larger slide. Therefore, individuals should avoid placing cleared debris, yard waste, or fill material on a steep slope.
Avoid modifications of the ground that disrupt or alter natural drainage, unless based on the recommendations of a qualified geologist or engineer. It has been reported that the effect of landslides is enhanced mostly by human activities. This for instance has been accounted in post-1840 Canada landslides which have resulted in more than 600 fatalities which include the destruction of several communities, and loss of billions of dollars.
There is a need for a critical review of the 1978 Nigerian Land Use Act, as through this, such unpleasant human activities as excavation, deforestation, irrigation or stream modification, blocking drainages by artificial fills should be subjected to the permission of Municipal Authority. For instance, the British Columbia Municipal Act contains legal requirements that deal with landslides and other hazards taking into account, mandatory engineering and geo-science investigations before structure erections.
Finally, the hazards presented by landslides involves not only failure of ground beneath a structure and the impact or burial of moving debris, but also such secondary effects as landslide-dammed floods and landslide-generated waves. However, landslide risk in our lives can be reduced or eliminated with proper planning and mitigation action.
Subscribe to this comment's feed
