The interdependence of the thermal and hydrologic processes of an Arctic watershed and their response to climatic change

Abstract

The heat and mass transfer processes which comprise the thermal and hydrologic regimes were monitored continuously from March 1985 until September 1989 in a small watershed on the North Slope of Alaska. Through these intense measurements, a better understanding of the physical processes which determine the character of an arctic watershed have been developed. The state of the hydrologic regime is a product of the thermal regime. The hydrologic and thermal regimes interact to such an extent that neither can be fully understood without considering the other. The consequences of a manmade or environmentally induced alteration in the thermal regime can have dramatic and perhaps dire effects on the hydrologic regime and vice versa. The implications of global warming reach beyond warmer air temperatures, milder winters and longer summers. The potential effects of climatic warming on the hydrologic regime of an arctic watershed were explored with respect to physical changes in the active layer and the resultant changes in the components of the annual water balance and the nature of the hydrologic cycle. With the advent of climatic warming, the annual depth of thaw in the permafrost will increase, affecting the amount of soil moisture storage, the depth to the water table, even the shape of the runoff hydrograph. The gradual thawing of the active layer was simulated using TDHC, a finite element heat conduction model which incorporated phase change. The results of four possible scenarios of climatic warming were input into HBV, a hydrologic model to elucidate the effects on the hydrologic regime. The results indicate an earlier, but less intense spring melt event, greater evaporation, greater soil moisture storage, and a potential for severe moisture stress on current vegetation types in early summer unless the precipitation pattern changes.