Questionnaire to Assess the Reliability of Current Methods for Determining Stream Discharge During Ice-Affected Periods, and to Identify
New Techniques



In Reply Refer To:                                     May 1, 1987
WGS-Mail Stop 415




OFFICE OF SURFACE WATER TECHNICAL MEMORANDUM NO. 87.09

Subject:  PROGRAMS AND PLANS--Questionnaire to Assess the
                              Reliability of Current Methods for
                              Determining Stream Discharge During
                              Ice-Affected Periods, and to
                              Identify New Techniques

The Office of Surface Water and the Branch of Operational Support
are conducting a project to assess the reliability of current
methods for determining stream discharge during ice-affected
periods and to identify any techniques which might improve our
ability to compute discharge during these periods. The study is
being conducted by the Iowa and Wisconsin Districts.  As a part of
this assessment, information is needed on the types and duration
of ice conditions encountered throughout the United States and the
methods used for determining discharge during ice-affected
periods.  We would appreciate your assistance by providing
information on current practice.  To provide this information,
please complete the attached questionnaire on ice conditions and
methods and forward by E-mail to NBMELCHER@DIAIWC (Nick Melcher
319/337-4191).

A response is requested by May 22, 1987.  For a complete
accounting of all areas, all Districts are requested to respond.
Thank you for your help.




                                   Verne R. Schneider
                                   Chief, Office of Surface Water

Attachment

WRD Distribution:  A, FO-LS



DISTRICT__________________________
COMPLETED BY______________________________


1.  Within each of the following climatic categories, defined by annual
runoff, how many gages in your District are in the listed subcategories?
These subcategories are defined by the number of days in which backwater from
ice affects the normal stage discharge relation.  Base the number of days on a
typical year.  Most Districts will have gages listed in only one or two
climatic categories.  The sum of the gages listed in the table should equal
the total number of gages in your District.

Less than                                  Greater than
.2 inch of  .2 to 2 inches  2 to 5 inches  5 inches of
annual      of annual       of annual      annual
runoff      runoff          runoff         runoff
(arid)      (semiarid)      (subhumid)     (humid)

Number of gages with:

No ice-affected days    _____        _____          _____          _____

1-5 days of ice         _____        _____          _____          _____
  effect/year
6-15 days of ice        _____        _____          _____          _____
  effect/year
16-45 days of ice       _____        _____          _____          _____
  effect/year
46-90 days of ice       _____        _____          _____          _____
  effect/year
91-150 days of ice      _____        _____          _____          _____
  effect/year
Greater than 150 days   _____        _____          _____          _____
  of ice effect/year


2.  Within your District, approximately what percent of the total number of
days in which the stage discharge relation is affected by ice is caused by the
following conditions?  If more than one condition exists simultaneously at a
gaging station, consider only the predominant condition.  (Your total percent
should equal 100 percent.)  (Descriptions of these ice conditions can be found
in Water-Supply Paper 2175, volume 2, pages 360-363.)

_____frazil ice           _____surface ice

_____anchor ice           _____shore ice


3.  Describe briefly the normal methods used by your District for determining
discharge during periods of ice effect.

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________


4.  Describe any techniques used by your District for determining discharge
during ice-affected periods which you think are unusual or have special merit.

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

5.  Describe any formal projects or backyard efforts which your office has
initiated or completed related to evaluating discharge during ice-affected
periods.  Briefly describe your efforts and conclusions or include a copy of
any reports with your response to this questionnaire.
__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________


6.  The following types of data are commonly used as the basis for determining
discharge during periods of backwater from ice.  Please mark an "X" next to
the data which are NORMALLY used by your office when computing or estimating
stream discharge affected by backwater from ice.

_____digital stage record                _____stream velocity record
_____discharge measurements              _____correlation with other stations
_____recession curves or coefficients    _____backwater shifts
_____discharge ratios                    _____measurements of ice thickness
_____ice roughness                       _____graphic stage record
_____air temperature                     _____winter precipitation records
_____snowcover records                   _____index stations
_____hydrographic comparison             _____observer information
_____other, please describe__________________________________________________


7.  How important is the availability of analog stage record for determining
discharge during ice-affected periods?

_____necessary      _____useful    _____unnecessary


8.  In your District, what is the frequency of discharge measurements made
during ice-affected periods?_________________________________________________


9.  Estimate, for your District, how many total hours of additional time are
used to process streamflow data for periods of ice effect.  Estimate the
additional field time necessary for data collection and office time to
compute, check, and review ice-affected periods.  "Additional" refers to the
extra time necessary to determine streamflow during ice-affected periods
compared with computing streamflow by the normal open-water method.

______total hours of field time   ______total hours of office time


10.  For the gages in your District affected by backwater from ice, how
important is the winter record in terms of data use?  In other words, to what
degree do users of the data consider accuracy of daily values during winter
record to be important?  Estimate the percent of ice-affected gages in the
following categories:

Percent of winter record where accuracy is

______extremely important          ______important

______very important               ______not important


12.  Data sets are needed to evaluate the available methods for computing
discharge during ice-affected periods.  Does your District have any stations
in which discharge is defined by frequent discharge measurements during the
ice-affected period (e.g., measurements at 7-10 day frequency)?  Describe
stations and data.
__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

__________________________________________________________________

RETURN COMPLETED SURVEY E-MAIL TO NBMELCHER@DIAIWC

(Nick Melcher 319/337-4191)