The natural role of a flood plain is to channel excess water during periods of heavy rainfall to rivers and other bigger channels.But where you have flood channels been blocked or walled off, then the artificially narrowed or blocked water must rise higher to compensate for the narrow channels, often time it becomes an embarrassment to a community.
CAUSES OF FLOODING
1) Deforestation- As activities of man becomes more intense, the trees around are being fell and these lands are claimed for other purposes. These areas will be exposed to flood as time goes on.
2) Development, Jobs and Affluence- like in every part of the world people loves to leave close to river because of economic and leisure gains, for farming (irrigation) ,water, transportation and even waste disposal.
3) Poverty- When you have too little to pay for a conducive environment, then you are most likely to settle for anywhere you find yourself, also constructing a drain gutter may be too expensive for you.
4) However not only areas close to rivers are prone to flooding, Unnecessary blocking of public drain channels and overbuilt environment may cause flooding.
5) Even in some houses bad foundation of buildings could lead to flood right inside your house. Areas with loose soils when building houses on them are expected to have water protecting membrane laid down round the foundation to prevent water rising to the floors through the walls from foundation. Also oversite concrete or german floor ought to be done for such area infact for every building, but the cost of doing it makes virtually anybody with low budget to ignore this important part of your building.
For those with considerably strong soil, you can use the method I used to at least saved some money, though not the best alternative.
What I did—–
After raising all the blocks to foundation level what I did was just to look for a carpenter to nail planks around the top of blocks (both internal and external) with about 100mm space to accommodate concrete directly on top, you may ask why did I do just that alone, as I said I am trying to save money and most of the water from ground will percolate through wall to the top and soon you may begin to see the effects.
To prevent flood , these are the major steps to take
(i) You can raise the foundation level of your building this will make your building to be higher but will probably save you from flood when the runoff is high. Though it will cost you more to raise the house from ground, it may perhaps be more economical at the long run, besides a well built house standing alone gives it an elegant look.
(ii) Make sure when paving the surrounding environment, the paving or whatever, slopes along water runway so that water entering your environment will naturally follow the gradient or slope of the land.
(iii) If you found out that your house is usually flooded after rainfall because the pavement/screeding of your environment was not done to slope towards the natural water flows, you can channel water from the roof of your house with a pipe to water channels, underground tanks or drain gutters.
(iv) Replace damaged pipes around the house, the ones from public utilities and your own.
(v) You can erect a retaining wall or fence made of concrete to block strong rushing water.
(vi) If number (v) is expensive you can use sandbags
(vii) The most important of all, when carrying out your project consider drainage gutter if you envisage future flooding problems.
(viii) In large scale done by Organisations and government, Dams,large water channels, and leeves are provided to further fights flooding. Leeves are embarkments composed of soil and earthen materials that are used to prevent annual flooding in many areas just like what you have in V.I bar beach presently been done by the Lagos state government. With a levee it requires very high volume of rain water before flooding can occur. But the drawback is that if the water level is high enough to past through the fence(levees) then the flooding will be most and will cause several times more damage.
(ix) If all fails, just move out. Leave the vicinity. Q.E.D