Seasonal and annual variations of surface water chemistry, solute fluxes and chemical denudation in a steep and glacier-fed mountain catchment in western Norway (Erdalen, Nordfjord).

摘要

Conducted during an investigation period of six full years (2004-2010), this study focuses on inter- and intra-annual temporal variations of surface water chemistry, solute fluxes, solute yields and chemical denudation in a steep, cold climate and glacier-fed drainage basin system in the fjord landscape of western Norway. The selected Erdalen drainage basin (79.5 km2) is considered a typical valley system of the Nordfjord region in western Norway and is connected to the Jostedalsbreen ice cap through two outlet glaciers. The mean annual chemical denudation rate in Erdalen is 6631 kg km-2 yr-1, which is of a similar range of magnitude for annual chemical denudation rates as a number of other cold regions catchments worldwide. Inter- and intra-annual temporal variations of surface water chemistry, solute gross concentrations, solute gross yields and chemical denudation rates are clearly determined by the combined effects of inter- and intra-annual temporal variations of precipitation, solar radiation and air temperature. Intra-annual temporal variations of surface water total dissolved solids (TDS) values reflect the dilution of base flow from the drainage basin by (i) thermally controlled snowmelt in spring (April-June), (ii) thermally determined glacier melt in summer (July-August), and (iii) more frequent and more intense rainfall events in autumn (September-November). The highest monthly solute gross yields over the year (comprising 43% of the total annual solute gross yield) are recorded in the spring period (three-month period from April to June), which is due to high runoff during spring snowmelt and comparably higher TDS values than during major glacier melt in summer (July-August). In autumn (September-November), comparably high amounts of ion-poor rainwater in combination with a fast surface drainage (saturation overland flow) of a significant share of rainwater during heavy rainfall events and lower air temperatures as well as lower solar radiation inputs lead to comparably lower TDS values in surface water than are found in spring.Digital Object Identifier http://dx.doi.org/10.1016/j.catena.2012.04.004