Human activities that cause flooding in Nigeria
It’s the raining season again and many places in Nigeria are currently experiencing flooding.
This is no surprise as the effect of flooding (in places that are developed and inhabited by people) can be very devastating, leading to the destruction of homes and other infrastructure, can lead to a loss of crops, the spread of waterborne diseases, and to loss of human life. Floods can also disrupt industry, water supplies, wastewater treatment, transport, education, and healthcare, essentially forcing many local economic activities to be halted until rebuilding takes place.
Naturally, during the raining season, there are things that lead to flooding and they include but are not restricted to heavy rainfalls, overflowing rivers, shallow and overflowing urban drainage basins, storm surges, tidal waves, channels with steep sides, climate change and lack of vegetation to help slow runoff.
On the other side, there are some activities by man that can lead to flooding.
1. Development and infrastructure in flood-prone areas
The development and building of infrastructure in flood-prone areas, such as along rivers, near ocean shorelines, or near river deltas, has led to an increase in vulnerability to flooding because the natural resiliency of the area to flood has been compromised by the development.
2. Blocked and narrow drainage systems
Dumping of refuse inside drainages can cause them to become narrower and then blocked leading to overflowing of and the area. Also when the drainages are not properly directed or are made too narrow, it doe not solve the problem of flood in the area but rather aggravates it.
3. Erection of buildings over flood drains and across canals
Construction of buildings over flood drains or water canals defeats the reason for the construction of the flood drains as they eject a huge amount of water from rainfall runoff back into the land and causing the area to become flooded.
4. Infrastructure failures
Floods can be caused by a breaking of an infrastructure that can cause large quantities of water to flood a local area. An example is when dams break due to faulty construction or maintenance, or when they are overwhelmed due to heavy rainfalls.
When the natural vegetation of an area is indiscriminately removed by cutting down the trees and hoeing of the area to remove grasses, there are no more trees to help soak up the water and reduce water flow over the landscape. Without these natural protections, the risk of flooding and erosion is increased whenever it rains.
6. Impermeable surfaces
In developed areas, like urban towns and cities, there are usually many impermeable surfaces like roads, concrete drainage basins, and other concrete structures that do not allow water to soak back into the soil. When large amounts of rain fall on these surfaces, the water then gathers and increase in volume thereby and leading to flooding of the low-lying areas if the runoff is not directed properly through a drainage that can handle the volume of accumulated water.
Sometimes, bridges that have been built over rivers can slow the discharge of water and reduce the river’s capacity to hold more water.
Ways that you can tackle flooding in your locality
As a responsible citizen, educate yourself and others on flooding and the way by which it can be reduced. The following are some of the actions you can take to reduce flooding in your locality:
- Help in every way to construct drains and ditches or embankments, to protect buildings, constructions, utilities etc.
- Never put refuse or solid materials in drains, and discourage others from doing so.
- Always help to clean gutters or drains and encourage others to do the same.
- Do not buy land in or develop places that are already vulnerable to flooding.
- Obey government instruction prohibiting you from building over flood drains and canals.
- Identify a higher place where you can run to during floods to prevent becoming a victim to floods because no amount of sympathy and relief can make up for the pain, grief and the losses you will suffer from the flood disaster.
- Don’t remove plants or trees unnecessarily, help to replant burnt or cleared forests
- We can plant trees in deforested areas and urban areas while also encouraging the government or those in the locality who are capable to intentionally develop parks and reserves for natural ecosystems that retain the ability to take up rainwater.
- Our development must involve the use of permeable materials for making surfaces that allow water to soak back into the soil instead of simply allowing runoffs to flow into and flood vulnerable areas.