Chapter one
Introduction
1.1 Background to the study

Floods are major disasters affecting many countries of the world annually especially in most flood plain areas. Floods do not only damage properties and endanger the lives of human and animals but also produce other secondary effects like outbreak of diseases such as cholera and malaria as well. Flooding is commonly caused by heavy downpours of rains on flat ground, reservoir failure, volcano, melting of snow and or glaciers e.t.c. Flood risk is not just based on history, but on a number of factors: rainfall, riverflow and tidal-surge data, topography, flood control measures, and changes due to construction of building and development on flood plain areas.

Flooding is caused by several factors and is invariably preceded by heavy rainfall. The other causes of flooding are moderate to severe winds over water, unusual hightides, tsunamis due to undersea earthquakes, breaks or failures of dams, levees, retention ponds or lakes, and other infrastructure that retains water. Flooding can be aggravated by impervious surfaces or by other natural and man-made hazards which destroy soil, vegetation that can absorb rainfall. Although flooding is a natural occurrence, man-made changes to the land can also be a factor. Development does not cause flooding but can make it worse. In cities and suburbs, pavement and rooftops prevent some rainfall from being absorbed by the soil. Thus can increase the amount of runoff flowing into low lying areas or storm drain system.

The significance of the year 2012 flood disaster in Nigeria lies in the fact that they were unprecedented in the past forty years. Most parts of the central states of Nigeria and other adjoining states along the river Niger and Benue are devastated by these floods causing huge destruction to the rural and urban infrastructures (farmlands/crops, roads, buildings, damages, bridges, power lines e.t.c ) and socioeconomic lives of the areas. Floods occur when the soil, stream channels and man-made reservoirs cannot absorb or contain all the water. A flood that occurs suddenly with little or no prior signs, is called a flash flood and is due to intense rainfall over a relatively small area, it us inevitable resulting from the natural rainfall runoff process. It is a natural phenomenon and its magnitude is periodic. The periodicity of flood implies that every year some area surrounding the river (on both sides) is flooded.

Flood disaster management like other disasters management can be grouped into phases; the preparedness phase where activities such as prediction and rusk zone identification or vulnerable mapping are taken up long before the event occurs, the prevention phase where activities such as forecasting early warning, monitoring and preparation of contingency plan are made before or during the event, and the response and mitigation phase where activities are undertaken after the disaster and these includes damage assessment and relief management (Van Western et al., 1993).

1.2 Problem Statement

In the last three  decades,  the  impacts  of  flooding  have increasingly  assumed  from significant to  threatening  proportions, resulting  in  loss  of  lives and  properties. Though detailed statistics  are  not available regarding  the  losses  sustained by  the  urban dwellers and  flood  victims,  it  is  obvious from  the available record that  irreparable havocs have  been  sustained  by the citizen  of  Nigeria due  to what  has become  perennial natural disaster in our  cities.  Apart  from  houses that collapse  by  flooding, schools buildings and  bridges  sometimes  collapse as  well. Markets places  and farmlands  are submerged  for  weeks and  sometimes are washed  away. Hence flooding in Nigeria needs to be assessed.

1.3 Objectives of the Study

The major objectives of the study is causes effects and solution to flooding in Nigeria.

1.4 Research questions

(1) what is flooding?

(2) what are the causes of flooding in Nigeria?

(3) what are the detrimental effect of flooding in Nigeria?

(4) what are the ways to proffer solution to flooding in Nigeria?

1.5 Significance of the Study

The research gives a clear insight into the causes, effects and solution to flooding in Nigeria. The research will help to identify the areas that are prone to flood. It will also help to know the ways to mitigate the effect of flooding.

1.6 Scope of the Study

The research focus on the causes effects and solution to flooding in Nigeria.

References

Ifatimehim and Ufuah, M.E (2006). Analysis of Urban Expansion and Loss of Vegetation in Lokoja using GIS Techniques. Zaria Geographers, 17(1): 28-36.

Ifatimehin, O.O., Musa, S.D. and Adeyemi, J.O. (2009). An analysis of the changing land use and Its impact on the Environment, Anyingba Town, Nigeria. Journal of Sustainable Development in Africa 10(4): 357-364.

Van Western, C.J.I., Van Duren, H.M.G. Kruse and M.T.J. Terlien (1993). GIZZI: Training package for Geographic Information Systems in Slope Instability Zonation. International Institute for Aerospace Survey and Earth Science (ITC), 15(1): 245 pp. Enschede, The Netherlands.