31 Jan 94
j. Duration of a data collection program.
i. Establishment of field data collection sites.
Before an ice forecasting system is established, it is
Based on the above discussion, locations of field data
best if data from several winters have been collected.
collection sites can be determined. There is a mini-
These should include at least one year when severe
mum number of sites that must be provided. How-
ice conditions were experienced. Winters during
ever, it is desirable to have additional sites located at
which no ice formed on the rivers are also valuable
intermediate points on the mainstem and the reaches
of the tributaries. At the intermediate sites, stage
However, it is very important that the data be
(from which discharge can be estimated), water tem-
collected during the winters when ice is present and
perature, and air temperature should be measured.
that these ice conditions be documented as described
The minimum data collection sites are:
(1) Upstream end of the mainstem. At this loca-
tion, discharge, water temperature, and air tempera-
ture must be measured. Hourly measurement is best.
This will allow the daily average values of each
A river ice forecasting system can be established
parameter to be accurately determined.
most efficiently if a comprehensive data collection
program is in place over several winters prior to its
(2) Upstream end of the reach of each tributary
establishment. It is often true that water temperature
to be included in the model. At these locations,
data and data on ice conditions are the most limited.
discharge, water temperature, and air temperature
The U.S. Army Cold Regions Research and Engineer-
must be measured.
ing Laboratory has developed effective, economical,
and accurate means of collecting both.
(3) Downstream end of the mainstem. At this
location, stage, water temperature, and air temperature
must be measured.
FOR THE DIRECTOR OF CIVIL WORKS:
PAUL D. BARBER, P.E.
Chief, Engineering Division
Directorate of Civil Works