Klaus Joehnk

01 Nov Klaus Joehnk

Klaus is a water quality modeller leading the Modelling Water Ecosystems team at CSIRO Land and Water. He is researching the impact of external drivers on aquatic ecosystems. His primary research areas include harmful algal blooms and continental scale modelling of aquatic systems.

Water quality in river systems and wetlands has deteriorated worldwide over the last decades due to intensification in land use and associated nutrient loading or changes in natural flow regimes. The most obvious impacts are increase in the frequency of harmful algal blooms caused by potentially toxic cyanobacteria and fish kills due to hypoxia. Other problems are not immediately visible or have indirect impacts like contamination by metals and pathogens, or vector borne diseases depending on wetting and increased temperature. To reduce health and economic risks posed by such water quality issues, there is an increased need for early warning systems integrating hydrodynamic and hydrologic modelling tools with advanced technologies from Earth observation or epidemiological models allowing for timely intervention and optimized management options.

Here we summarize available techniques and give examples from case studies from the Murray River system, Australia, which is especially plagued by harmful algal blooms occurring more frequently in the last decade leading to significant losses in the tourism industry but also affecting water treatment plants. Satellite remote sensing allows us to follow the development of such blooms in the upstream, seeding reservoir and hydrodynamic simulations provide operating strategies for risk minimization. A generalization of these combined methods will allow not only for Early Warning but also for short-term prediction of algal blooms using weather forecasts. Furthermore, combining satellite imagery for flood inundation and hydrological modelling with large scale water temperature simulations in the Lachlan catchment allows us to characterize the physical environment for fish in this system. This information is combined with a demographic and epidemiological model for carp to research the spread of a carp specific virus meant to reduce this invasive species. The system will be upscaled to the entire Murray Darling Basin.

View the 2018 Presentation here