FLOODING: CAUSES & PREVENTIVE MEASURES
Have you ever experienced the agony of living in a flooded community? Within few hour of heavy rain; lives are lost, properties are gone, heavy traffic jam, the frightening of destructing
Flooding is a common natural disaster in Nigeria, both in the rural and urban areas which affect millions of people around the globe.
WHAT IS FLOODING?
Flooding is the excess of water on the surface of the ground when it rains, normally such lands are dry lands, except there is rainfall particularly, when there is small portion of land to absorb the water.
How it works
Soil types/land has a specific water holding capacity. If the rainfall exceeds the water holding capacity of a land, it results to flood. Water holding capacity is the amount of water a land can absorb, contain or hold without surface runoff. One the land water holding capacity is filled, water starts to rise above the ground level resulting to surface runoff.
Loamy soil has the highest water holding capacity followed by sandy soil and finally clay soil. These characteristics accounts for the ability of loamy soil to absorb a lot of water and nutrient.
CAUSES OF FLOODING IN NIGERIA
Most times houses buildings are submerged, people’s properties are destroyed. This is unfortunate. Some may ask, what are the causes of flooding particularly in urban cities
Poor Drainage System
Some of the drainage system in Nigeria are not constructed and maintained well. Rural and urban dwellers misuse the drainage by dropping refuse, sewage; reducing its effectiveness and capacity to allow flow of water. When there are no proper and adequate drainages in the urban cities or towns and sometimes, there could be these drainages in the urban cities but poor planning when building drainages in the cities, of course, we know that in urban cities, there is very small portion of land to absorb rain water when it rains. Flooding can also be caused b y dumping of refuse into drainages
Another cause of flooding is heavy rainfall
Improper planning of building structures
Moreso, if someone builds in the water way, the possibility that he will block the waterway during rainfall thus, causing flooding.
HOW TO PREVENT FLOODING IN NIGERIA
Flooding can be prevented in many ways, but much more important is that, while wanting to prevent flooding, the first thing that should come to mind should be effective mitigation measures and proper planning. You can prevent flooding when proper planning is taken into consideration. Much of these measures should be taken in areas that are prone to flooding.
Construction of Dams
A dam is a barrier that stops or restricts the flow of water or underground stream. It is an effective way of flood control. Dams were originally built especially for flood control in developed countries. Many large dams have flood control reservation in which the level of a reservoir must be kept below a certain point before the rainy season. During the rainy season, flood water is allowed to fill the dam restricting them from destroying lives and properties. If we consider the dam as an open tank filled with water. Before the rainy season, tank is emptied in order to create space for rain water during the raining season; reducing flood in the community
Building Dikes and Levees
Dikes and levees are flood-control structures built to fight river flooding and water surges. Dikes and levees restrain rivers during floods by providing artificial water channels that prevent runoffs from bursting floodplains. Floodplains are natural waterways that carry excess river water during heavy rainfall. Dike engineers/constructors alter and develop floodplains by building dikes and levees to boost flood-prevention when floodplains well up.
Improve Flood warning system
Flood warning system is a way of detecting threatening events in advance. This warns the public in advance so that actions can be taken to reduce the adverse effect. Properly conveying advance warnings of impeding storms and floods will not only give people the opportunity to be proactive in preventing damage to their property, it will save lives. Warning signs should be indicated in areas prone to flood; preventing interested buyers from falling victims of such area. It also warns drivers to avoid that route.
Flood resilience is the capacity to recover from flood. This is an efficient method compared to river defence. Buildings and other urban infrastructures should be designed or structured strategically; making it easier to recover from flood. For example, water proofing homes and businesses and moving electrical sockets higher. Green roofs can be implemented. This is the process of building houses with vegetative roofs. Vegetative roofs contain soils: which absorbs rain water reducing flood. However this is expensive to build and maintain.
Create Flood Plains
Flood plains are lands that have the capacity of absorbing large amount of water. It diverts water from flooded communities; reducing the flood. This is a method of conservation as flood plains are used as natural reservoir; where communities can fall back on during drought. In some countries, wilderness and deserts have been re-engineered to act as flood plains. This should be looked into in Nigeria. Flood plains also serve as natural habitat for aquatic animals.
Preservation of wetlands and planting of trees
Reforestation should be encouraged in Nigeria. Reforestation is a term for planting of trees which reduces the impact of flood. The trees absorb water, slowing down the overflow of rivers to neighboring communities. Wetlands will soak up moisture and wooden areas: slow down flood when river overflows. Creating wetlands and reforestation is a good environmental practice
Building Diverting Canals
Canals are artificial water channels that can be crucial to flood prevention. Canals facilitate control of water levels passing through, and form linear reservoirs and water locks. During flooding, excess water is channeled through canals to non-risk areas further downstream or to other areas with high demand for water, such as arid and semi-arid areas. Canals can also be used to lock excess flood waters in its linear reservoirs to prevent flooding and store water for future use. Canal delivers water from flooded communities to a city where water is needed. Canals can link several cities together i.e. Canal can lead Abuja and Kaduna state; crowning it’s efficiency. Floods can be controlled by redirecting excess water to purpose-built canal. Canal is also used to confine or lock water.
Harvesting Rain Water
Harvesting rainwater involves collecting and storing rainwater and can not only prevent floods; it can also curb urban water scarcity. Harvested rain water can be cleaned for human consumption and distributed to people in rural areas, as well as urban areas in times of water scarcity. Rain water harvesting is carried out in different ways, including building ponds, storm drains, water retention basins and flood-control dams.
Flooding can be prevented with improved drainage
Like I mentioned earlier one of the causes of flooding is dumping refuse into drainages. With such fact in place, flooding therefore can be prevented through improved drainage. When drainages are improved, there will be easy access for water during rainfall. Flooding can be controlled and prevented when the drainages are improved because it will help ensure that there is a way for easy flow of excess water during and after rainfall. This type of measures should be taken in the urban cities, where there are many cases of flooding problems. The efficacy of drainage may be improved to control flooding. This could be achieved firstly through rehabilitation of drainage system in the urban cities. Next is that the drainage system has to be cleaned, this is done by removing refuses, including solid wastes that may have blocked the drainage systems.
Refuse and sewages block the drainage system and canal pathway, preventing the flow of water making them inefficient. Canals, drainages should always be cleaned regularly, removing debris etc. people should be warned against indiscriminate dumping of refuse and sewage in the community, drainage or canal. This is the cheapest way of preventing flood in Nigeria
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