A water balance model for a subarctic sedge fen and its application 16 to climatic change

• Main Author: Wayne R. Rouse
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1998
• Subjects: Priestley; Subarctic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.461.8706; http://research.eeescience.utoledo.edu/lees/papers_pdf/Rouse1998_ClimCh.pdf

Abstract. A model to calculate the water balance of a hummocky sedge fen in the northern Hud-son Bay Lowland is presented. The model develops the potential latent heat flux (evaporation) as a function of net radiation and atmospheric temperature. It is about equally sensitive to a 2 % change in net radiation and a 1 C change in temperature. The modelled potential evaporation agrees well with the Priestley–Taylor formulation of evaporation under conditions of a non-limiting water supply. The actual evaporative heat flux is modelled by expressing actual/potential evaporation as a function of potential accumulated water deficit. Model evaporation agrees well with energy balance calculations using 7 years of measured data including wet and dry extremes. Water deficit is defined as the depth of water below reservoir capacity. Modelled water table changes concur with measurements taken over a 4 year period. When net radiation, temperature and precipitation measurements are available the water balance can be projected to longer time periods. Over a 30 year interval (1965–1994) the water balance of the sedge fen showed the following. During the growing season, there was an increase in precipitation, no change in temperature and a decrease in net radiation, evapotranspiration and water deficit. There was also a decrease in winter snow depths. The fen was brought back to reservoir capacity during final snowmelt every year but one. Summer rainfall was the most important