THE ENVIRONMENTAL IMPACT OF FLOODING ON TRANSPORTATION LANDUSE IN BENIN CITY, NIGERIA

Introduction

In general, the environment provides all life support system in the air, water, on land and in the forests (Glasson et al; 1999). However, the Nigeria environment generally, and Benin City in Edo State in particular, today presents a grim litany of woes across the length and breath of the country. Environmental problems therefore manifest as a result of different land use activities of man to earn his living and his livelihood. In the urban land use, deforestation has become a peculiar problem in Nigeria and Benin City in particular, which results from uncontrolled logging and tree felling for the purpose of urban development. In many parts of the Southern States of Nigeria, this goes with its loss of precious biological diversity. Afolabi (2005) noted that the environment is itself, the point in which one is found at
a time, the surroundings, the more distant places, other earth components, conditions, prospects and problems which account for its flourishing or otherwise. Flooding can be described as high water stage in which water overflows its natural or artificial banks on the normally dry land, such as stream or river  inundating its adjacent lowlands.

In this regard, geophysical hazards can be wrought on civil artifacts, facilities, other aspects of human activities and occasionally loss of human lives may be incurred, (www.vision 2010.org, 2009).  Adebayo (1987) recognized four major mechanisms for the increase in the flooding potentials of urban catchments. The first one is increasing the percentage of impervious surface that infiltrates in the ground and increase in the total volume of runoff. Secondly, paving, straightening or otherwise improving stream channels, all of which reduces the time lag between rainfall and channel runoff. Thirdly, landscaping and subdivision of land into building sites, a process that shortens the distance over which the water flows before reaching drainage way and hence reduces the time lag between rainfall and channel runoff. Lastly, filling in and human settlement on flood plains, which reduces the space available for storing flood waters. African Research Review Vol. 4(1) January, 2010. Pp. 390-400

The phenomenon of flood hazards, according to Ward (1978), comprises several aspects including structural damage, loss of lives and properties, disruption of socio-economic activities including transport, communication and the destruction of agricultural land. According to Ayoade (1979), floods are natural phenomena rather than natural disasters. They, like drought, form part of the normally occurring range of stream flow conditions. Flood disasters are man-made as they occur when and where man puts himself at risk by developing and occupying floodable areas, there by causing damage, congestion and hold ups to the transportation networks in the area. Man,
therefore, develops and occupies flood plains, at risk of flooding, out of ignorance or for economic reasons.

The basic cause of urban flooding is man’s modification of the basin network and channels characteristics during the process of settlement on the particular flood plain (Adeleke, 1978). Natural surfaces are replaced by more impermeable roads and concrete which have very low infiltration capacity. The hydrological consequences of this is that water which should normally infiltrate into the ground or be intercepted by vegetation and then delay for some time before running, would be immediately available for runoff. This
considerably decreases the lag time between rainfall and storm water and increase the runoff with concomitant increase in peak discharge and total volume of runoff (Adeleke, 1978).

Aim and Objectives of the Study

The aim of this study is to investigate the propelling environmental mechanisms of flooding prevalent in the Benin City Metropolis as they affect transportation land use.
The specific objectives of this study are to:-
i. Identify the causes of flooding prevalent on transportation land use in Benin City.
ii. Examine the environmental problems of flooding on transportation land use in Benin City.
iii. Recommend possible control measures on the problems of flooding on transportation land use in Benin City.
The Environmental Impact of Flooding on Transportation Land Use…

The Hypotheses

i. There is no significant difference between the causes of flooding on
transportation land use in the Benin City Metropolis.
ii. There is no significant difference between the environmental
problems of flooding on transportation land use in the Benin City Metropolis.

Decision Rule

The null hypothesis (H0) will be rejected, if the ‘t’ calculated value is greater
than the ‘t’ table value at (alpha level of 0.05). If otherwise, the alternative
hypothesis (Hi) will be accepted.

The Study Area

Benin City has a history of being one of the foremost destinations of Europeans during their exploration of African continent many centuries ago, (www.edo-nation.net, 2008). Some of her flash points have remained enviable tourist attractions for the state. Benin City is the capital of Edo State. Benin City lies approximately between latitude 60 201 North of the equator and longitude 50 371 East of the Greenwich meridian. The distinct relief regions in Benin City are the swamps/creek. In the Benin low land is found sandy coastal plain and alluvium clay with some hills in the East. River Osse, Orhionmwon and Ikpoba drain the area.

Soil types in the Benin low land ranges from loose poorly productive sand in the South-east to fertile clayey soil in the North-east close to the Niger, the Osse and Benin drainage basins have alluvial and hydromorphic soils. The climate of Benin City is typically tropical with two major seasons. The wet (rainy) and the dry seasons. The wet season lasts from April to November and the dry season from December to March. The natural vegetation of Benin City consists of tropical rainforest in the Benin low lands. Human interference has, however, led to the presence of plantation for rubber and oil palm as well as forest reserves.

The main ecological problem in Benin City is flooding, soil erosion and scarcity of water and out crops of basement rocks. Flooding and erosion are acute in Oredo, Egor and Ikpoba-Okha local government area of Benin City. Rainfall and the removal of vegetal cover and unplanned land use development are the main cause of the problem  Transportation in Benin City is mainly by road and to some extent by air and water. On road transportation, Benin City is transverse by a network of Federal (Trunk A), State (Trunk B), township and rural earth roads (Benin
City 2005)