FLOOD MODELLING

A flood model is a computer program that produces flooding information for future times and gives alert for evacuation. Flood models are used to simulate, predict and estimate real flood events and how rain infiltrates into the ground and travels long way into Creeks and rivers. The models also calculate how flood waters travel along rivers and how the water flows across flood plains and through Rural and Urban areas. Example if flood occur the model can predict the areas the flood will extent to (flood), how fast the water moves and the depth it will reach. Just like the flood alert giving by the National Emergency Management Authority (NEMA), during the Makurdi flood (2012), in Nigeria. That the flood will reach Delta, Anambra, Kogi kwara, Niger and Kebbi State and the prediction is correct.

Design flood: With the help of flood model, the environment of flood plains, can be design by the town planners who have to minimize the risk of flooding to new develop areas of flood plains, by setting controls like minimum floor level for building.  

The controls:

i.    The building floor height should be 500mm above in one in a hundred years

      Design flood.

ii.    Flood ways should be constructed

iii.   Regular monitoring of new building {to check if it reaches 500mm or not}.

Data collection: Different data are required as input to a flood model before it may be used.  

Some data needed are:

i.          The depth of the flood plain: Data are collected by the use of airborne       

             survey method or ground, to know the height above mean sea level of the

             river and the flood plains.    

        

ii.         The velocity of the flood plain: The tidal current of the ocean push the

             water down to the flood plain, it can speed up to 5m/s in coastal waters.

             Tide currents generate internal waves; it may suspend bottom sediment

             even in the deep ocean.