The influence of hydrodynamic processes on the brownification of rivers and lakes

This project investigates how brown water is distributed in rivers and lakes and how its dynamics are influenced by the hydrodynamics of this water bodies. Moreover, it aims to provide information of brownification sources.

During the last decades lakes and rivers have become browner in water colour, which results in huge problems for the water treatment plants. The increase in colour is caused by dissolved organic matter and iron which leach from the soil and are introduced into streams. Moreover, dissolved organic matter is also produced by plankton and macrophytes. In addition, brownification is probably attributable to reduced sulphur emissions in combination with land use change. Seasonal variations are noticeable when observing surface waters, however the colour varies also spatially within a lake.

Already today much research on brownification is ongoing from the biological approach, the investigation between the processes of brownification, hydrology and hydrodynamics have hardly been investigated. This project investigates how brown water is distributed in rivers and lakes and how its dynamics are influenced by the hydrodynamics of this water bodies. Moreover, it aims to provide information of brownification sources.

The lake Bolmen in Sweden, which is one of the main sources for drinking water in southern Sweden has been chosen for this study. The main purpose of this project is to deepen this knowledge and give a holistic perspective on the ongoing processes from the engineering perspective.

Objectives

  • How and why does brownification vary during the year and how is the change in colour related to the season, flow and the origin of the water
  • How is browned water mixed and distributed in the lake and what does it mean for the future regarding the lake as drinking water source?
  • Modelling of unobserved weather conditions and try to generalize the results to lakes with different characteristics