Environmental Assessment
Volume E-3.8
Tailings Facility
Hydrology
Ambatovy Project
66
January 2006
Table 3.8-2 Maximum Daily Precipitation Frequency Analysis for Tailings Facility
Return Period
2-yr
5-yr
10-yr
20-yr
50-yr
100-yr
maximum daily precipitation (mm)
159
224
273
326
402
465
Reference: Madagascar Ministry of Public Works and Transport, Meteorology Branch 2005.
Note: Daily precipitation totals are from 7 am to 7 am.
Table 3.8-3 Derived Monthly and Annual Runoff for Tailings Facility
Monthly Runoff (mm)
Early Dry Season
(April/May)
Late Dry Season
(October/November)
Peak Wet Season
(January – March)
Annual Runoff
(mm)
150
50
100 (upper basin)
225 (lower basin)
1,700
Note: Based on data from the 2004-2005 monitoring program.
3.8.4
Issue Scoping
Hydrology issues related to the project were identified through consultation with
stakeholders and by reviewing previous environmental assessments for resource
developments in Madagascar and elsewhere. The following hydrology issues
were identified (Volume A, Section 6):
•
changes in flows, water levels and sediment loads that could alter
channel morphology and sediment concentrations; and
•
changes in water availability for various uses (human and animal
consumption, irrigation and aquatic habitat).
The key indicators of change due to the project are flows, water levels, sediment
concentrations and channel morphology. These changes may also have an effect
on water quality (Section 3.10 in this volume), fish health (Section 4.3),
vegetation (wetlands)(Section 4.1), and socioeconomic components of the project
(Section 5.1).
The Key Questions for the hydrology surrounding the tailings facility are:
Key Question H-1
What Effect Will the Tailings Facility Have on
Flows and Water Levels in Water Bodies?
Key Question H-2
What Effect Will the Tailings Facility Have on
Sediment Levels in Water Bodies?
