Environmental Assessment
Volume C-3.6
Slurry Pipeline
Hydrology
Ambatovy Project
51
January 2006
Figure 3.6-1 Derived Mean Annual Precipitation Along the Pipeline Route
0
500
1000
1500
2000
2500
3000
3500
0
20
40
60
80
100
120
140
160
180
200
220
Pipeline Distance from the Ore Preparation Plant (km)
Mean Annual Precipitation (mm)
Table 3.6-1 Maximum 24-Hour Rainfall Amount
Maximum 24-Hour Rainfall (mm) for Various Return Periods
Area
2-yr
5-yr
10-y
20-yr
50-yr
100-yr
pipeline km 0-30
(a)
122-172
181-242
231-295
287-352
374-434
453-502
pipeline km 30-200
(b)
172
242
295
352
434
502
(a)
Interpolated between rainfall amounts for the mine and tailings areas based on differences in annual precipitation.
(b)
Assumed to be equal to conditions at the tailings area.
Table 3.6-2 Typical Derived Monthly and Annual Runoff for Pipeline Route
(Based on 2004-2005 Monitoring Program)
Monthly Runoff
(a)
(mm)
Area
Annual
Precipitation
Early Dry Season
(April/May)
Late Dry Season
(October/November)
Peak Wet Season
(January – March)
Annual
Runoff
(mm)
Pipeline km 0-15
1,750
25-35
5-10
100-150
500-600
Pipeline km 15-25
2,000
50
15
140
730
Pipeline km 25-100
2,500
90
30
175
1,100
Pipeline km 100-130
3,000
125
40
200
1,500
Pipeline km 130-187
3,300
150
50
225
1,700
(a)
Runoff along the pipeline is estimated by interpolation between the mine area and tailings area.
