Physical modelling of the Akkajaure reservoir

• Main Author: Sahlberg, Jörgen
• Format: Article in Journal/Newspaper
• Language: English
• Published: Affärsverksamhet 2003
• Subjects: temperature profile; reservoir; 1-D lake model; stratification; Sweden; Oceanography; Hydrology and Water Resources; Oceanografi; hydrologi och vattenresurser; Northern Sweden
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:smhi:diva-1347

This paper describes the seasonal temperature development in the Akkajaure reservoir. one of the largest Swedish reservoirs. It lies in the headwaters of the river Lulealven in northern Sweden: it is 60 km long and 5 km wide with a maximum depth of 92 m. The maximum allowed variation in surface water level is 30 m. The temperature field in the reservoir is important for many biochemical processes. A one-dimensional lake model of the Akkajaure reservoir is developed from a lake model by Sahlberg (1983 and 1988). The dynamic eddy viscosity is calculated by a two equation turbulence model, a k-epsilon model and the hypolimnic eddy diffusivity formulation which is a function of the stability frequency (Hondzo et al., 1993). A comparison between calculated and measured temperature profiles showed a maximum discrepancy of 0.5-1.0degreesC over the period 1999-2002. Except for a few days in summer, the water temperature is vertically homogeneous. Over that period of years, a weak stratification of temperature occurred on only one to two weeks a year on different dates in July and August. This will have biological consequences.