THE EFFECT FLOOD ON LAND UTILIZATION: DISASTER PREVENTION IN NIGERIA.
Abstract
Some environmental effects of flooding in the Niger Delta region of Nigeria was reviewed to provide the desired knowledge needed for the effective management of flooding. Floods are caused by many factors: Heavy rainfall, highly accelerated snowmelt, severe winds over water, unusual high tide, tsunamis, or failure of dams, levees, retention ponds, or other structures that retained the water. Flooding can be exacerbated by increased amounts of impervious surface or by other natural hazards such as wildfires, which reduce the supply of vegetation that can absorb rainfall. The effects of flooding from the sources outlined above are felt by various ‘receptors’. These include, people, buildings, infrastructure, agriculture, open recreational space and the natural world. Flood warning is the provision of advance warning of conditions that are likely to cause flooding to property and a potential risk to life.
CHAPTER ONE
- Background of the study
Flooding is one of the major environmental crises one has to contend with within the century. This is especially the case in most wetlands of the world. The reason of this is the general rise in sea level globally, due to global warming as well as the saturated nature of the wetlands in the Niger Delta. Periodic floods occur on many rivers, forming a surrounding region known as flood plain. Rivers overflow for reasons like excess rainfall. The good thing about river overflows is the fact that as flood waters flow into the banks, sand, silt and debris are deposited into the surrounding land. After the river water subsided and go back to its normal flow, the deposited materials will help make the land richer or more fertile. The organic materials and minerals deposited by the river water keep the soil fertile and productive (Abowei and Sikoki, 2005)
The main purpose of flood warning is to save life by allowing people, support and emergency services time to prepare for flooding. The secondary purpose is to reduce the effects and damage of flooding. Floods renew wetland areas which in turn host a wide range of flora and fauna. Preventing flood waters from entering such wetland areas will create imbalance to the natural state of things resulting to destruction of natural habitats and even extinction of various species of animals and plants. Floods play an important part in various ecosystems. Humans, therefore, should be careful when they try to prevent or control floods. Oftentimes, human intervention causes more harm than good. During times of rain or snow, some of the water is retained in ponds or soil. Some is absorbed by grass and vegetation, some evaporates and rest travels over the land as surface runoff. Flood occurs when ponds, lakes, riverbeds, soil and vegetation cannot absorb all the water. Water the runs off the land in quantities that cannot be carried within stream channels or retained in natural ponds, lakes and manmade reservoirs. About 30% of all precipitation becomes runoff and that amount might be increased by water from melting snow. A flood that raises rapidly, with little or no relatively small area, or if, the area was already saturated from previous precipitation (Henry, 2006). During flooding water supplies that result in contamination of water (water pollution). Clean drinking water becomes scarce. Unhygienic conditions and Spread of water-borne diseases result. People, buildings, infrastructure, agriculture, open recreational space and the natural world. In extreme cases flooding may cause a loss of life. Torrential rains pushed rivers over their banks, collapsed mud houses and washed away livestock (Adelye and Rustum, 2011). Damage bridges and caused a dam to overflow, submerging buildings, displacement from homes, the loss of personal valuables and the ongoing fear and insecurity caused by the experience. Potable water supplies may be lost or contaminated in a flood and this can have immediate health effects upon people and animals. The economy can also be severely affected by flooding. Businesses may lose stock, patronage, data and productivity and disruption to utilities and transport infrastructure can have knock-on effects to a wider area. Tourism, farming and livestock can equally be affected. Vital infrastructure may also be damaged or disrupted. Electricity and gas supplies can be interrupted to individual properties but also to wider communities if sub stations and transformers themselves are flooded. Road links, railways, canals etc., may be blocked causing disruption to the wider transport network and accessibility severely disrupted for local inhabitants, especially amongst those considered most vulnerable and loss of communications networks (Adelye and Rustum, 2011).
People, floods can be quite beneficial. Actually, believe it or not, nature benefits more from natural floods than from not having them at all. The thing that makes natural floods a disaster is when flood waters occur in areas populated by humans and in areas of significant human development. Otherwise, when left in its natural state, the benefits of floods outweigh the adverse effects (Bradshaw et al., 2007). However, too much sand deposit will do the opposite.
