CONTROLS ON RUNOFF PROCESSES IN THE LITTLE CHAZY RIVER WATERSHED, NORTHEASTERN NEW YORK

The Little Chazy River originates in the Adirondack foothills and flows eastward to Lake Champlain. Nearly 70% of the watershed lies in the Champlain Lowland, a broad, low relief region underlain by Cambro-Ordovician sedimentary rocks and Late Pleistocene glacial, lacustrine and marine sediments. Local relief in the predominantly forested uplands exceeds 200 m and watershed slope commonly exceeds 20 m/km. Thin glacial soils overlie sandstone and meta-anorthosite bedrock in the uplands.

Records from three stream gaging stations and meteorological stations at Miner Dam and Chazy were used to examine runoff processes in three nested sub-watersheds: Cold Spring Brook (area=0.8 km²), the Little Chazy River at Miner Dam (area=29 km²) and at the river mouth near Chazy (area=142 km²). The Cold Spring Brook and Miner Dam sub-watersheds are located in the upper Little Chazy River basin. These sub-watersheds lie wholly or partially on Altona Flat Rock, a broad area of exposed sandstone bedrock thinly veneered with organic-rich soil. Storm runoff is typically flashy with lag-to-peak times averaging about 5 hrs for Cold Spring Brook and 20 hrs for the Little Chazy River at Miner Dam. The steep slopes and relatively low infiltration capacity of soil and bedrock are the primary controls of upland runoff. Beaver activity and the moisture-retention capacity of the moss and lichen ground cover on much of Altona Flat Rock, complicate runoff generation, especially during low flow conditions. Unit peak storm flow discharge (discharge/basin area) at the Chazy gage is generally less than one-half that of unit peaks for the same runoff event at Miner Dam and lag-to peak time averages about 30 hours. Runoff in the lower portion of the watershed is a complex function of geology, topography, and land use; the magnitude and timing of tributary inputs; channel and floodplain storage effects; antecedent soil moisture; and stream flow-control structures.