Between 2004-2007 ' Helderheid meren (Lake clarity) ' focuses on activities for the implementation of the Water Framework Directive. We want to expand the knowledge on ecological relationships and methods to quantify these relationships, in order to describe and understand the interactions between the biological quality elements of lakes and hydromorphological conditions and water quality parameters. The project has two final products:
1. calibrated and validated implementation of macrophytes in the Delft Systems DELWAQ and HABITAT
2. knowledge database of habitat requirements of aquatic flora and fauna species relevant for the WFD (indicator species)
This year (2004) a macrophyte module was implemented in the DELWAQ process library and the existing model MACROMIJ of RIZA, together with an HSI model for Chara vulgaris which has been implemented in HABITAT. In the coming years, these modules will be validated and calibrated and higher trophic levels will be taken into account since the existence of an interaction between macrophytes and water quality has long since been acknowledged.
The implementation of the macrophyte module in DELWAQ was started by making a base-line model of the alternative steady states in shallow eutrophic lakes (a clear water state vs. a turbid water state) using Excel. Sensitivity analyses were used to determine the most important factors causing changes in the ecosystems on long time scales (over several years). The functional design of the macrophyte module will use this knowledge in the coming years, and focused this year on the growth and decay of macrophytes in relation to the most important chemical processes in shallow lakes. |
