AQUATIS a.s. has been engaged in analysing and modeling surface water quality, especially in the catchment areas of water supply and recreational reservoirs affected by eutrophication for a long time. The developed qualitative models have become effective tools for detailed analyses of catchment areas as well as water reservoirs themselves, for balancing all sources of pollution (point and non-point) and for simulating real processes in the river network during the pollution spreading, including the self-cleaning capabilities of water courses and reservoirs. The balance models can give a very good idea of the scope and structure of pollution in various areas of the river network and thus enable identification of key sources of pollution that need to be focused on.
The qualitative models make it possible to simulate impacts of various scenarios of measures, establish the most effective measures, and target public and private funds to areas with the highest cost effectiveness. 
Examples of developed qualitative and balance studies of river and water reservoir catchment areas:
• Study of the Clean Svratka catchment, Qualitative model of the river basin upstream the Brno hydraulic structure 
• Feasibility study for implementing measures at the Brno hydraulic structure
• Implementation of measures at the Brno hydraulic structure, stage I – IV
• Reduced eutrophication in the Slezská Harta hydraulic structure catchment 
• Qualitative model of the Jihlava river basin upstream the Dalešice hydraulic structure
• Study of the aquatic environment in the Svitava region 
• Study of water quality improvement in the Vranov hydraulic structure
• Qualitative model of the Jihlava river basin upstream the Nové Mlýny hydraulic structures
• Assessment of the effect of the Dukovany NPP new unit on the state of water bodies downstream the Mohelno hydraulic structure to the Nové Mlýny hydraulic structures
• Assessment of the effect of increased wastewater volumes from the Mondi Štětí paper mill on water quality in the Elbe
• Optimization of water and soil protection in water resource basins - analysis of the Bílý Potok basin in relation to the Vír hydraulic structure
• Water quality in the Hostivař hydraulic structure
• Study on the improvement of water quality in the Hracholusky hydraulic structure 
• Hlučín lake - analysis of the risks of changes in the management and flow regime on water quality 
• Feasibility study of measures to reduce phosphorus transfer to the Orlík hydraulic structure
• Vlachovice hydraulic structure – study of water quality in the catchment are, forecast of water quality in the reservoir
• Modeling the importance of sources of phosphorus and measures proposed in the Elbe river basin