monitoring of currents and the estimation of the rate and distribution of waste 
materials in an estuary; both currents and frontal systems play an important part in 
determining the dispersal patterns. Anyone concerned with the selection of off- 
shore drilling sites in the Beaufort Seas, or with evaluating the consequences of an 
oil spill, obviously must be made fully aware of the value of remote sensing. This is 
particularly important in areas such as the Arctic, where other sources of 
information are meagre and the collection of data is difficult and expensive. 
This year an atlas of the shoreland resources of the Great Lakes was com- 
pleted. The project originated with an inventory of the severe damage and 
shoreline erosion that occurred in 1975 through a combination of high water levels 
and storms; losses were mostly along the shores of Lake Ontario, Lake Erie and 
parts of Lake Huron. The methods used in completing the atlas are described by 
Haras, Taui, Scullion and Robinson (1976) and include ground surveys, interviews 
with land owners, the use of old survey records, but also remote sensing and, as is 
not unusual when reliable results are required in a hurry, the contribution of remote 
sensing was through aerial photography. Photogrammetric profiles of the 
shorelines were plotted and digitized every 1.5 km and the volume of eroded 
material and the rate of erosion were calculated from 1952 and 1975 measure- 
ments; information on sediment movements in the near-shore zone is also provided. 
The atlas provides not only a baseline for future monitoring and an assessment of 
past damage, but also gives a picture of current trends and thus is an invaluable 
guide to individuals and governments concerned with land use policies along the 
shores of the Great Lakes. This project is but one example of baseline setting and 
monitoring programs along important inland water bodies where erosion, deposition 
(Figure 10) and the activities of man are recognized as major influences on 
resource values. 
Ice reconnaissance 
The efficiency and safety of shipping in northern waters require reliable, up- 
to-date information on ice conditions. Ships have to know the status of the breakup 
or freeze-up of water ways and they must be kept informed about the movement of 
the pack ice, about ice characteristics, thickness and the size of floes: they 
require situation reports and forecasts. Ice data are also used for weather 
forecasting: the development of certain cloud types is associated with open water, 
and freedom from clouds during the development of low pressure systems is often 
associated with ice pack. 
The Canadian ice reconnaissance and ice forecasting system, operated by the 
Ice Branch of the Atmospheric Environment Service, covers the Arctic and the 
Eastern Seaboard, the Gulf of St. Lawrence and the Great Lakes. It is a good 
example of the effective operational combination of remote sensing and visual 
observations. Data are collected by Electra aircraft, supported by smaller aircraft 
for operations over the Gulf of St. Lawrence, the St. Lawrence Seaway and the 
Great Lakes. The two Electras are fitted with an inertial navigation system, an 
airborne radiation thermometer, laser profilometer, infrared line scanner, radar 
and camera system. This equipment is operated by ice observers, who also Carry 
out visual observations from a special position in a bubble on top of the aircraft. 
The bulk of the forecasting is based on visual observations and satellite data. 
Radiometric data, radar observations and aerial photography are used to suppl- 
ement this information where cloud inhibits sketch mapping. Weather permitting, 
ten hour flights are carried out three or four times weekly, and following a day's 
flight, the information is sent by telecopier to Ottawa where it is combined with 
interpreted NOAA 4 data. An example of receding ice, as it appears on imagery of