Akinyemi, F.O. 
“where the extent, nature or location of a proposed project or activity is such that is likely 
to significantly affect the environment, its environmental impact 
assessment shall be undertaken ...” . 
The decree seeks to ensure that the likely environmental impact of implementing projects are given adequate 
consideration particularly during project identification and planning. 
To successfully model and monitor impacts of proposed projects on the environment, the mapping of the 
spatial component of the environment may be crucial. This paper describes a case study of the determination 
of a 400 km long high voltage (330 KV) transmission line (HVTL) route for the electricity utility company in 
Nigeria based on the policy of environmental sustainability. Environmental impact was assessed based on 
vulnerability of a given environmental facet within the potential corridor to detrimental perturbations during 
construction of the HVTL and/or maintenance of the right-of-way. Geographical Information System (GIS) is 
applied in the following EIA stages: Screening and Scoping; Baseline conditions description; Impact 
significance: and Mitigation and Control (See also Mgendi, 1999). Indices used in the assessment include the 
vulnerability to gullying in particular areas of high soil erodibility and sufficient available slope); vulnerability 
to accelerated eutrophication of water bodies consequent upon erosion in the near - channel areas, and 
perturbation of streambed sediments; potential synergistic changes to physiognomy and species composition of 
vegetation; and, the potential loss of wildlife due to opening up of reserves. 
2 STUDY AREA 
The proposed corridor lies between latitude 6° 20'N and 7° 37' N and longitude 7? 23! E and 9° 01' E, and 
traverses the part of Nigeria known as the eastern Nigeria Scarpland, and the western part of the Benue 
Trough. It covers a total distance of 400 km between Udi in the south, Enugu in the west, and Makurdi and 
Yandev in the north and east respectively (Figure 1). The corridor traverses the Koppen’s Aw (Tropical Wet 
7°E 0 0 
PN E PE 9°E 
  
8°N 
    
to Kano: 1 
  
Okpobi Forest ^ 
Reserve Unum mem D e m 
     
   
   
  
NE 
  
CAMEROON 
  
   
  
Gulf of 
  
  
  
  
  
  
  
  
  
E Benin 400km 
6°N | ¥ to Pt [Harcourt J 6°N 
0 40 80km : +++ Railway LI Expressway 
LÁ —À ; Proposed corridor 
Main Road — o HVTL Route 
7E 8°E 9°E 
Figure 1: The Study Area showing the Proposed HVTL Route 
  
28 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000.