Hydrology and Geochemistry of Small Tundra Drainage Basins in Response to Active Layer Disturbance. Progress Report

摘要

Hydrology of far northern drainage basins in which the shallow organic-rich surface layer overlies a permanently frozen substrate, is poorly known, yet is of great importance in evaluating natural stability and in predicting response to disturbances effecting flow and the distribution of nutrient and sedimentary ions. First-year study of a 2.5 km sup 2 watershed supports the primacy of the short duration melt-off in the yearly hydrologic/geochemical cycle. At this time basin storage capacity is minimum and total runoff carries with it a seasonal maximum of nutrient ions, suspended and dissolved solids. Subsequent to melt-off, base flow is high but decreases as thaw releases seasonally frozen water, including some temporarily stored melt-off. Spring storm events produce rapid peak discharges because of the low storage capacity in the catchment. Rare, high intensity, short duration storms in early season can produce discharges that rival diurnal peaks at melt-off. With activation of vegetation following melt-off, some nutrient ions are no longer detectable and pH becomes acid. Summer drought periods are common and if sufficiently protracted, reduce stream flow to barely measurable quantities. At such times hydrographs may show small diurnal fluctuations in response to evapotranspiration cycles. Ion concentrations show an increase as senescence commences in mid-August. (ERA citation 11:048733)