Environmental and Social Impact Assessment - Gibe III

Gibe III – Environmental and Social Impact Assessment 300 ENV R CS 002 C - A9003099
9.2.5 Downstream effects
Inundation of the river crossings, loss of scenic river areas such as rapids and waterfalls, access to the water,
variations of flow during the day due to peak electricity demands are only some of the possible downstream
effect that will be considered. A weight of 10 will be given to this criterion and the impact will be scored as
described in the following Table 9.6.
9.2.6 Aquatic ecosystems
Table 9.6: Impact of downstream effect
Score Downstream effects
0 None
1 Low
2 Medium
3 High
A weight of 10 will be given to this criterion and the impact will be scored as described in the following
Table 9.7.
Table 9.7: Impact on ecosystems
Score Expected Ecosystem modification
0 None
1 Low
2 Medium
3 High
9.2.7 The Scheme Impact Score
The weighting and the score range for the seven criteria that were selected in order to rank the different
schemes in terms of their environmental impact is summarized in the following Table 9.8.
Table 9.8: Scheme Impact Score
Criteria Weight Score Range
Land lost: Forest 5 1-5
Agricultural land 15 1-5
People affected 35 1-5
Access 15 0-3
Cultural 10 0-3
Downstream effects 10 0-3
Aquatic ecosystems 10 0-3
TOTAL 100
The maximum score will amount to 100; a higher score means a higher impact.
The score for each scheme will be calculated as follows:
SIS =
∑
Cw*
Cs
Mps
CESI SpA - Mid-Day International Consulting Engineers Page 259