Page:Niger Delta Ecosystems- the ERA Handbook, 1998.djvu/171

Environmental Impact of the Oil Industry Thus, regardless of the oil industry, there has been and will continue to be:
 * forest degradation,
 * conversion of forest to agricultural land,
 * soil degradation
 * degradation of fish habitats and depletion of fish stocks

A number of external pressures will increasingly have an adverse impact upon the environment of the Niger Delta. The three most important are as follows:

As discussed in the earlier chapter about Sand Barrier Islands, the human activity that has the most profound impact on the deposition/erosion relationship which shapes the delta are forest clearance and the construction of dams. Dams trap sediment, reducing the amount of sand available for deposition. It has been estimated that 70% of the sediment once available to the Niger delta from the Niger/Benue river system has been lost in this way (Collins and Evans in 1986). However increased sedimentation arising from forest loss may be making some compensation.
 * Upstream dams


 * Pollution caused by upstream activities

The Fresh and Brackish-water ecozones of the Niger Delta are the last terrestrial sink for the drainage of much of Nigeria and a very large chunk of West Africa. Thus the industrial effluent of Kaduna, Onitcha and all the other cities in the Niger/Benue river basin end up in, or at least pass through, the Niger Delta. Plastic bags, in particular, are becoming a usual part of the sediment load.


 * Rising sea levels resulting from global warming

The 1995 World Bank Report suggests that the Niger Delta is particularly at risk because of its low elevation. A 1m rise in sea level would flood 18,000 km² of Nigeria, severely disrupting the oil and gas industry, forcing up to 80% of the delta’s population to relocate, in addition to destroying much agricultural land, forests and fisheries.

15.3.3 THE AGENTS OF THE IMPACT

The potential oil industry agents of impact upon the environment are implied in Chapter 14.3 In summary these include the following.


 * surveying and clearing paths for the receiver cables,
 * laying the receiver cables and retrieving them,
 * boring 3-6m holes for the seismogelite explosive shots, and
 * detonating the explosives.

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 * sealing the drilling site,
 * construction of the 50m derrick,
 * mixing and use of drilling fluids,