Rm. Lent et al., MULTIVARIATE CLASSIFICATION OF SMALL ORDER WATERSHEDS IN THE QUABBIN RESERVOIR BASIN, MASSACHUSETTS, Journal of the american water resources association, 34(2), 1998, pp. 439-450
A multivariate approach was used to analyze hydrologic, geologic, geog
raphic, and water-chemistry data from small order watersheds in the Qu
abbin Reservoir Basin in central Massachusetts. Eighty three small ord
er watersheds were delineated and landscape attributes defining hydrol
ogic, geologic, and geographic features of the watersheds were compile
d from geographic information system data layers. Principal components
analysis was used to evaluate 11 chemical constituents collected bi-w
eekly for 1 year at 15 surface-water stations in order to subdivide th
e basin into subbasins comprised of watersheds with similar water qual
ity characteristics. Three principal components accounted for about 90
percent of the variance in water chemistry data. The principal compon
ents were defined as a biogeochemical variable related to wetland dens
ity, an acid-neutralization variable, and a road-salt variable related
to density of primary roads. Three subbasins were identified. Analysi
s of variance and multiple comparisons of means were used to identify
significant differences in stream water chemistry and landscape attrib
utes among subbasins. All stream water constituents were significantly
different among subbasins. Multiple regression techniques were used t
o relate stream water chemistry to landscape attributes. Important dif
ferences in landscape attributes were related to wetlands, slope, and
soil type.