PROGRAMS AND PLANS--A U.S. Geological Survey (USGS) Climatological Discharge Data Network

In Reply Refer To:                               February 4, 1988
WGS-Mail Stop 415



Subject:  PROGRAMS AND PLANS--A U.S. Geological Survey (USGS) Climatological
                              Discharge Data Network

The Water Resources Division (WRD) is seeking to define a climatologic dis-
charge data network by identifying those stations in WATSTORE which would be
suitable for mesoscale climatic analyses.  Jim Slack (Branch of Regional
Research/WR) and Jurate Landwehr (Branch of Regional Research/NR) have been
working with Charlie Riggs (Office of Surface Water (OSW)) and myself to
identify stations appropriate for inclusion in such a network.

Several different collections of stations that have been used for climatologic
or related analyses by researchers in the WRD were merged into a single col-
lection.  This station list was given an initial review by OSW.  Annual water
summaries for each State were also reviewed for possible additions to this
list.  We are now requesting your help in reviewing the compiled station list.


The USGS collects discharge information for several thousand stations through-
out the United States and its territorial areas.  This data-collection effort
is motivated by societal concerns, e.g., establishing information with which
to secure public water supplies or to mitigate against flood damages.  It must
be an ongoing activity because the phenomenon of interest--streamflow--varies
over time.

The variability of streamflow is a function not only of the inherent variabil-
ity of the hydrologic cycle, but also the variability of the climatic system
in which the cycle is embedded, as well as the variability of the economic and
social demand for water.  However, in many areas, though certainly not all, it
is the climatic variability which is dominant, and a major shift in the
climate system would engender a major shift in the hydrologic regime as well.
Consequently, for both operational and research interests of the Division, it
will be useful to have one commonly defined data set of high-quality discharge
stations identified as the "USGS Climatological Discharge Data Network."


A network such as we are discussing cannot be all things to all people.  In
particular, it cannot be expected to characterize the stochastic behavior of
micro-hydrologic conditions.  Such questions must be addressed on a local,
case-by-case basis.  Rather, the spatial scale of the basins which would com-
prise this network should be in the mesoscale range, i.e., comparable in size
to hydrologic units of the WRD as well as to the climatological divisions of
the National Weather Service.  Such a scale is fine enough to distinguish be-
tween climatologically distinctive areas as well as appropriate for aggrega-
tion upward to a general circulation model (GCM) scale.

Initially, the resolution for the variability of interest will be on a rather
gross time scale, such as monthly or even seasonal averages.  The pattern of
diurnal or even weekly cycles will not be captured.

Consequently, criteria by which stations should be considered for inclusion in
such a network are:

1.  Long records:  n>=20
    Preferably, n>=50, but the 20-year threshold was chosen to allow the
    inclusion of the benchmark stations.

2.  Good quality data.
    This pertains to the quality of the stage record, the discharge measure-
    ments, and the stage-discharge relation.

3.  Broad geographic and diverse climatologic representation across the

4.  Minimal anthropogenic effects in basin, including minimal regulation of
    the stream discharge or reduction of base flow due to extreme ground-water

5.  Basin size generally should be mesoscale, i.e., 100 to 1,000 square miles.
    However, this need not be a hard and fast rule:  there is some merit in
    including the records from the "Big Five" rivers at one end of the scale
    and the benchmark stations, at the other, if criteria number 2 is met.

In striving for geographic coverage, particularly in the Southwest, the ques-
tion of including ephemeral streams may arise.  If such a stream should meet
the above-stated criteria, it may be considered for inclusion but should be
identified as such.

There may be several strategies that could be used to obtain appropriate
geographic density.  For example, Byron Aldridge, WR, has suggested two
approaches which could be considered:  (1) choose one or two stations within
each hydrologic accounting unit which is most representative of hydrologic
conditions in that unit; or (2) select one station for each rectangular area
unit that is 1 degree of latitude by 2 degrees of longitude, starting with a
few minutes between odd longitudes in the mountainous regions.

The number of stations in the network should not exceed 500; the more realis-
tic number is probably 300 nationwide.


There are several different collections which have been or still are in use by
different offices of WRD, although none completely satisfy the above criteria.
These include National Water Conditions data set (C); NASQAN, active and
inactive (N and n); Benchmark (B); Miniregions (M); Langbein-Slack (L); and
Alley-Lins (A).  (See attached footnotes for further explana-tion.)  These are
termed "Other Compilations."  Charlie Riggs, OSW, has provided an initial
screening of this mega-list as well as examining the State data reports for
other prospective stations, identified as "OSW."

The list of stations by District can be found in the file JRS.BIGLIST which is
located in the RVARES FTS_DEPOT.  For each State, these is a subdivision into
two lists, namely "Stations suggested by OSW" and "Stations in other compila-
tions."  Other compilations in which stations appear are identified in the
left margin.

We ask that you consider the stations in your District and indicate agreement
or disagreement with the stations suggested by OSW, in light of the forestated
criteria.  Are there any stations from the other compilations that also should
be considered?  Are there any other additions which do not appear in any of
the compilations that also should be considered for inclusion in such a data
base?  Comments as to why further additions should be considered, especially
in preference to the listed stations, would be helpful in our deliberations.

If you have further questions, please do not hesitate to call Jurate Landwehr
(FTS 959-5893) or Jim Slack (FTS 459-7201).  Please return comments to J. M.
Landwehr (USGS, MS-430, Reston, Virginia 22092) before March 1, 1988.

                                       Verne R. Schneider


WRD Distribution:  A, B, S, FO


(C)  The National Water Conditions data set is the subcollection of
     discharge stations (besides reservoirs and wells) used in the
     monthly National Water Conditions report of the USGS.

(N and n)  See "The National Stream Quality Accounting Network (NASQAN) -
     Some Questions and Answers" by J. Ficke and R. Hawkinson,
     Geological Survey Circular 719, 1975.  (Stations designated "N"
     were active as of 1985.)

(B)  See "A National Network of Hydrologic Benchmarks" by L. B.
     Leopold, Geological Survey Circular 460-B, 1962.

(M)  The miniregions data set was compiled by N. C. Matalas and J. M.
     Landwehr, with the help of Don Thomas and Gary Tasker, then in the
     Branch of Surface Water , drawing upon, but also expanding, the
     data set of Hardison.  (See Water Resources Research, v. 10, no.
     5, 1974.)  Unlike the latter, which had specifically been con-
     structed to examine peak discharge records, the miniregions data
     set was constructed with the goal of looking at the spectrum of
     flow conditions, low to high, with minimal controls imposed on the
     low end.

(L)  See "Yearly Variations in Runoff and Frequency of Dry Years for
     the Conterminous United States, 1911-1979" by W. B. Langbein and
     J. R. Slack, Open-File Report 82-751, 1982.

(A) The Alley-Lins data set was compiled for hydro-climatic data
    analysis by informal poll of all District offices, drawing on the
    Langbein and Slack work and on the National Water Conditions
    stations.  See "Interannual Streamflow Variability in the United
    States" by H. Lins, Water Resources Research, v. 21, no. 5, May