Physical modelling of the Akkajaure reservoir

• Published in: Hydrology and Earth System Sciences
• Main Author: Sahlberg, J.
• Format: Text
• Language: English
• Published: 2018
• Subjects: Northern Sweden
• Online Access: https://doi.org/10.5194/hess-7-268-2003; https://www.hydrol-earth-syst-sci.net/7/268/2003/

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 –ε 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 0.5–1.0°C 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. Keywords: temperature profile,reservoir, 1-D lake model, stratification, Sweden