Posted by on 1/29/2003 1:25:10 PM
Post Comment PHYSICAL SETTING Nigeria

Geology: Delta State is a part of the Niger Delta Structural Basin in which three major sedimentary cycles have occurred since

Inner Compound of Chief Nana's Palace
Inner Compound of Chief Nana's Palace

the early Cretaceous. The subsurface stratigraphic units associated with the cycles are, the Benin, the Agbada and the Akata Formations (Kogbe, 1976). The surface rock throughout the state consists of the OgwashiUku formation. The Benin formation is about 1800m and con sists of loose and unconsolidated sands.

There is little hydrocarbon associated with it. The underlying Agbada Formation which consists of sandstone and shales is, however, rich in hydrocarbons. It is up to 3000m and is underlain by the Akata Formation. The OgwashiAsaba Formation that underlie the northeast consists of an alternation of lignite seams and clay.

Relief: The entire Delta State is a region built up by the sedimentation of the Niger Delta and con sists of the delta in various stages of development. Four major physiographic units are identifiable with in it. First, the freshwater swamp which is the most active area. It is located close to the River Niger, where annual flooding and deposition occurs up to 45 km from the river's course.

Second, the man grove swamp area described as an intermediate delta stage. It is much lower and a great proportion of it is brackish, having been invaded by the sea since large amounts of freshwater have ceased flowing into it. Third, the upland and swamp, which is also called the coastal plain.

It lies between the flood plain and Benin lowlands. The swamps are more restricted to broad drainage channels created when this area was an active delta. Fourth and finally, the upland Niger valley, which is a narrow strip above the delta and relatively floodfree. The town of Asaba is located in this region.

Drainage: The River Niger drains the eastern flank of the state and discharges into the sea through its several distributaries such as the Forcados, Escravos and Warri rivers and creeks such as the Bomadi creeks, amongst others. Rivers Jamieson and Ethiope rise from the north and northeast respectively, and subsequently join and form the Benin River, which eventually dis charges into the sea in the West.

Climate: Delta State is situated in the tropics and therefore experiences a fluctuating climate, ranging from the humid tropical in

Delta Steel Complex, Aladja
Delta Steel Complex, Aladja

the south, to the subhumid in the northeast. The lessening of humidity towards the north is accompanied by an increasingly marked dry season.

The average rainfall is about 266.5mm in the coastal areas and 1905mm in the extreme north. Rainfall is heaviest in July. Temperature increases from the south to the north. In Warri, located in the south for example, the average daily temperature is 30C, while the temperature in Asaba in the north eastern area is 44C.

Vegetation: The vegetation varies from the mangrove swamp along the coast, to the evergreen forest in the middle, and the savannah in the north east.

Soil: There are three types of soil in Delta State. These consist of alluvial soil on the marine deposits along the coast; alluvial and hydromorphic soils on marine and lacustrine deposits found in the area closest to the Niger and Benin rivers; and the ferral soils on loose sandy sediments in the dryland areas of the north and northeast. The ferral soils are usually yellowish in color.

Ecological Problems: The environmental setting of Delta State has very serious ecological problems such as erosion and flooding. Coastal and creek erosion affect the coastal areas, resulting in loss of farm and residential land, and in some cases whole village such as Ogulaha and Ugborodo (Ibe,1988).

Flood is a widespread phenomenon in the state. In the coastal area, the numerous rivers and creeks flood their banks creating social and eco nomic problems. Flash floods and flood pondages are the major features of the drylands, especially in the urban centres of Warri, Sapele and Ughelli.

In recent times, oil exploitation and gas flaring have further aggravated the ecological problems, causing very serious environmental pollution. The consequences include the destruction of aquatic life and vegetation and reduction in soil productivity.

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