7812

• UCREFRP Catalog Number: 7812
• Author: Many
• Title: Rivers, Studies in the Science, Environmental Policy, and Law of Instream Flow
• USFW Year: 1990
• USFW - Doc Type: Rivers
• Copyright Material: YES

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• REGRESSION LINE
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MEAN BASIN ELEVATION (FT.)
FIGURE 4. Regression of cfsm versus mean basin elevation for unregulated New England rivers.
A review of climatic data indicates dif-
ferences in rainfall throughout New En-
gland during the month of August (NOAA
1979). Differences in average August rain-
fall between northern and southern New
England range from 2.87 to 4.95 inches,
and are in part attributable to a greater
intensity of storm events and occasional
hurricanes which strike southern New En-
gland but miss northern New England
during the August through September pe-
riod. Coastal, interior, and mountain cli-
matic zones in New England are recog-
nized by the NOAA and used for classifying
precipitation and evaporation. Runoff in
coastal New England also differs from that
of northern and interior New England due
to differences in topography and land use
in much of Connecticut, eastern Massa-
chusetts and Rhode Island versus that of
western Massachusetts, Vermont, New
Hampshire, and parts of Maine.
The USGS gage files for all six New En-
gland states were reviewed to identify var-
ious types of physical basin characteristics.
This review indicated that the USGS has
identified rainfall, mean basin elevation,
mean channel slope, and percentage of for-
est cover to be basin file data categories
potentially influential upon river flow. As
the review proceeded, it was determined
that six gages with significant regulation
of August flow had been inadvertently in-
cluded in the original USFWS New En-
gland ABF data base and that an additional
seven gages that meet the criteria for in-
clusion were available for analysis, but had
not been included. A complete list of the
gages used in the following analysis is pre-
sented in Table 2. Gages used in the orig-
inal New England ABF data base, but with
August regulation, are noted also in Table
2, but were deleted from further analysis
after consultation with the USGS. August
median flow was determined for each gage
by selecting the median flow value from
August flow duration data, for the full pe-
riod of record available from USGS data.
Regression analysis indicated that,
among the basin characteristics reviewed,
cfsm values correlated best with mean ba-
sin elevation (r2 = 0.49); correlation of cfsm
values with other basin characteristics was
poor. A scatterplot of the gages (flow ver-
sus mean basin elevation) indicates a pro-
nounced polarization of cfsm values above
and below the regression line at mean ba-
sin elevation greater than approximately
1,200 feet (Figure 4). A possible explana-
tion of this pattern of polarization was giv-
en by Chow (1964), indicating that a rain
shadow effect was responsible. In New En-
I -I B. H. Kulik 17 IN