Author(s): Hannah Clercx; Wouter Kranenburg; Julie Pietrzak
Linked Author(s):
Keywords: Stratification; Lake physics; Density driven flows; Internal waves
Abstract: In The Netherlands, multiple estuaries have been closed off from the sea to improve coastal safety. However, various of these systems experience water quality issues, strongly related to the two-layer stratification that develops in summer, inhibiting downward mixing of dissolved oxygen. We study the spatial-temporal behavior of the stratification, circulation and mixing in enclosed former estuaries, systems that do show characteristics of lakes but also estuarine features. In saline lakes, stratification can occur due to both salinity and temperature differences. These differences can induce density driven flows when affected by wind. Wind stress can result in a setup of the surface of the lake, creating a pressure imbalance which is compensated for by the tilting of the pycnocline. Furthermore, when wind stress disappears, the tilting interface can develop into seiching, creating basin-sized internal waves. Tilting of the thermocline may result in upwelling of the lower layer. In this study, we present measurements of temperature and flow velocity, aiming to quantify the stratification in Lake Veere, located in the southwest of the Netherlands. We use this data to study how the stratification arises and develops, and what the effects of environmental factors such as wind and rainfall are on the stratification intensity, thermocline dynamics and circulation and mixing in these systems.
Year: 2025