WP2. Lake Modelling

Lead: Dennis Trolle (AU, Denmark) Email: trolle@bios.au.dk
Co-lead: Anders Nielsen (AU, Denmark) Email: an@bios.au.dk
To quantify physical, chemical and biological processes and interactions, we will apply and adapt a state-of-the-art, one-dimensional, hydrodynamic-ecological model to Lake Bosumtwi. Historical data and new high-frequency data compiled by WP1 will be used to calibrate and validate the new GOTM-FABM-PCLake model (Hu et al., 2016). The model simulates thermal stratification and mixing processes, and describes interactions between multiple trophic levels, including piscivorous, zooplanktivorous and benthivorous fish, zooplankton, zoobenthos, phytoplankton and rooted macrophytes. The model also accounts for oxygen dynamics and a fully closed nutrient cycle for nitrogen and phosphorus. Such a model has not previously been set up for Lake Bosumtwi and will, in combination with data from WP1, make it possible to assess future changes in thermal stratification and primary production related to climate and land use.

Main Deliverables

Ø      Develop one-dimensional hydrodynamic-ecological model for Lake Bosumtwi

Ø      Design scenarios of future climate change on lake physics, chemistry and primary production

Task 2.1: Acquire and format limnological data from WP1, and weather forcing time series from historical records as well as from reanalysis data (interim and the new ERA5 dataset) from the European Centre for Medium-Range Weather Forecasts (ECMWF).

Task 2.2: Setup and calibrate model of lake hydrodynamics and biogeochemistry (based on approx. two years data from the NSERC/LRBP project).

Task 2.3: Validate model performance for Lake Bosumtwi based on data collected in WP1.

Task 2.4: Design scenarios of potential future climate, sediment and nutrient loads, based on already available climate projections for Ghana (e.g., review by Asante and Amuakwa-Mensah, 2015) and estimates of future watershed sediment exports derived from WP4.

Task 2.5: Make future projections of lake physics and primary production, based on scenarios designed in Task 2.4. These projections can serve as input to WP3 and WP5, for assessment of potential impacts on fisheries and livelihoods associated with Lake Bosumtwi.

Lake Model