• 

The redevelopment of water resources management in areas influenced by lignite mining has to be planned carefully and in great detail. While conceptualising the flooding of open pit lakes and integrating them into the hydrosystem, sustainable decisions have to be made.

Those decisions include the provision of flood water, the maintenance and cultivation of the lakes to ensure high water quality, as well as monitoring water quality which is necessary for an effective lake treatment. Furthermore, operational decisions based on the latest hydrological and hydrochemical characteristics of rivers have to be made to release water from already flooded lakes. Decision support tools for water quality control and management have been developed for areas of the Spree River watershed influenced by lignite mining,. The models are of the same degree of abstraction as deterministic block models. The hydrogeochemical modelling core consists of PHREEQC [Parkhurst&Appelo]. The hydrochemical models are compatible with the well- established flood control model GRMSTEU, as well as with the water management model WBalMo. Hydrochemical models use the discharge forecasts of GRMSTEU and WBalMo as input. In the models, rivers, open-pit lakes and groundwater bodies are linked based on the principle of mass balance. The realtime provision of data needed for the water quality control model is achieved by an efficient cooperation between the redevelopment agency LMBV, relevant water users, and public authorities.

Case of applications:

• Prediction of contaminants (sulphate, ammonium, iron) in effluents of open-pit lakes; monitoring of discharged water quantities (based on the salt load principle)
• Prediction of water quality in open-pit lakes within complex river basins and assessment of alternative flooding and cultivation strategies
• Water management optimisation in linked water storage systems, respecting water budget and water quality issues
• Optimisation of raw material application for in- and on-lake treatment

• 
• 
• 
•