FINAL REPORT - International Joint Commission

Collection of detailed bathymetric and topographic surveys in wetland areas using boat surveys was
acceptable, although not all wetland sites were mapped with desired sounding densities due to dense
vegetation growth. Surveys of this type are expensive and require substantial labour to conduct.
ANNEX 2
Use of Flood Damage Reduction Program (FDRP) maps in Ontario to delineate topographic detail in
wetland areas was unacceptable. The accuracy of these base maps was not sufficient to derive dependable
0.5-metre contour accuracies in these environments.
Airborne LIDAR data collection was carried out on the lower St. Lawrence River floodplain in November
and December 2001. Collection of conventional bathymetric and topographic LIDAR survey data was
conducted in Quebec in early May 2001, and within acceptable error bounds, providing maximum utility
throughout the remainder of the Study process. The upland extent of these surveys included all areas that
could be inundated under all potential regulation scenarios. Collection of topographic LIDAR surveys of
the floodplains along the lower St. Lawrence River in autumn was very successful, providing maximum
coverage with the lowest-cost technology.
Figure I-3: Irondequoit Bay and Rochester, New York, digital elevation model
Imagery Collection/Processing
Aerial photography was collected over many of the nearshore areas where intensive investigations would
be conducted by other technical work groups (e.g. Coastal, Environmental, Recreational Boating, Municipal
Water Use). Aerial photography was also the basis for photogrammetric terrain derivations and feature
collection efforts. If resources were more extensive, comprehensive collection of high resolution
(i.e., 0.15-m (0.5-ft) pixels) photography/imagery would have been preferable.
High resolution satellite imagery (1 to 5-m (3 to 16-ft) pixels) was only utilized for the Montreal archipelago
region. This type of information could have utility elsewhere, but can be expensive, and it can also be
logistically difficult to obtain coverage over large tracts of irregular geography.
Options for Managing Lake Ontario and St. Lawrence River Water Levels and Flows
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