Effects of wind-driven circulation on river intrusion in Lake Tegel: modeling study with projection on transport of pollutants

Abstract

Prediction of mixing intensity of water masses in riverine Lake Tegel (Berlin, Germany) can be used to trace the fate of pollutants that enter the lake through several inflows. Because the contributions of each inflow have not yet been quantified and because the lake features complex bathymetry and numerous islands, a hydrodynamic circulation model with high spatial resolution and dynamic wind forcing is useful. We applied the two-dimensional version of the Princeton Ocean Model to separate the influences of wind and river discharge on the currents and mass transport in Lake Tegel. For model validation, we compared the simulation results with 1 year of electrical conductivity data, which was used as a conservative tracer to distinguish between water from the River Havel and water supplied by a smaller second inflow. Calculation of currents alone is insufficient to investigate water exchanges between rivers and lakes, especially when several islands create multiple pathways for river intrusion. Therefore, mass transport simulations are applied. Our calculations based on archetypical scenarios indicate that the proportion of (polluted) water from the River Havel in the main basin of Lake Tegel fluctuates with river discharge and wind, which either amplify or neutralize each other.

Hydrodynamic modelling and characterisation of a shallow fluvial lake: a study on the Superior Lake of Mantua

“…Well-mixed conditions along the water depth were assumed, as verified by field measurements (Fenocchi, 2015). In fluvial lakes, the through-flowing current provides a background turbulence, preventing stratification even under no-wind conditions, so that baroclinic effects Rueda et al, 2003) can be neglected (Rubbert and Köngeter, 2005;Anderson et al, 2010;Schimmelpfennig et al, 2012). Indeed, small temperature gradients may be present in the deepest parts during summer drought periods.…”

“…shallow basins with perceptible through-flowing current (Neuendorf et al, 2005), have an even more dynamic behaviour, circulations being shaped by the interaction between wind and discharge, with variable influences according to their relative intensity and direction (Anderson et al, 2010;Schimmelpfennig et al, 2012). Being often located in the lowland reach of river basins, where nutrient loads are maximum, they are extremely sensitive to discharge reductions, caused by meteorology and water diversion.…”

“…Hodges, 2014 for a list of references), fluvial lakes have received less attention (Rubbert and Köngeter, 2005;Anderson et al, 2010;Schimmelpfennig et al, 2012), so that knowledge about their circulation modes and their modelling is weaker. This paper describes the setup and application of a numerical model aimed at reproducing the significant physical features shaping circulations in the Superior Lake of Mantua, a small shallow fluvial lake in Northern Italy which hosts vast lotus flower (Nelumbo nucifera) canopies.…”

Surface seiches in Flathead Lake

“…Horizontal eddy viscosity was modeled by the Smagorinsky diffusivity (Smagorinsky, 1963) with a nondimensional coefficient C = 0.2. We adopted a simple bottom stress parameterization based on the law of the wall and the thickness of the logarithmic layer dependent on the lake depth from Schimmelpfennig et al (2012). The circulation was forced by an initial linear tilt of the lake surface of 0.5 × 10 −6 , corresponding to the surface slope produced by surface wind stress of approximately 3× 10 −4 m 2 s −2 , corresponding to winds of about 8-10 m s −1 .…”

Pilot-Scale Investigation of Micropollutant Removal with Granular and Powdered Activated Carbon

“…The present treatment process includes coagulation/flocculation, sedimentation, and rapid dual-media filtration (Heinzmann and Chorus 1994). A lake pipeline pumps water from a point near the outflow of Lake Tegel to the PEP to increase flow and decrease the phosphorus concentration in the lake in summer (Schimmelpfennig et al 2012). Water supply to parts of Berlin is affected by the water quality of the lake (Grünheid et al 2005;Wiese et al 2011), as more than 100 drinking water wells are installed along the shores of Lake Tegel, extracting lake water via bank filtration.…”