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PITLAKQ - Processes
PITLAKQ accounts for the important processes in pit lakes. The figure shows the processes that are explained in the table below.
Please click on the picture to enlarge.

Process | Description | Implementation |
---|---|---|
hydrodynamics | Solution of the Navier-Stokes-Equation in two dimensions with density-dependent flow. Calculations of velocities, water temperature distribution and hence stratification. | CE-QUAL-W2 |
transport | Transport of dissolved substance in the lake. Added about 20 species. | CE-QUAL-W2, PITLAKQ |
heat exchange | Budgeting of heat terms at water surface. | CE-QUAL-W2 |
wind impact | Wind energy effects water velocity of upper most lake layer. | CE-QUAL-W2 |
ice cover | Formation and melting of ice layer. Prevents atmospheric exchange during ice-covered periods. | CE-QUAL-W2 |
tributary inflow | Inflow from an unlimited number of sources (flow, concentrations, and temperature). | CE-QUAL-W2 |
atmospheric exchange (O2) | Oxygen can enter and leave at water surface layer. | CE-QUAL-W2 |
atmospheric exchange (CO2) | Carbon dioxide can enter and leave at water surface layer. Solubility depends on temperature and pH. | PITLAKQ |
precipitation | Precipitation enters surface layer with amount, temperature and concentrations. | CE-QUAL-W2 |
evaporation | Water evaporates from surface layer. | CE-QUAL-W2 |
groundwater exchange | Groundwater characterized by flow, temperature and concentrations can enter and leave lake at any given cell. | PITLAKQ |
groundwater flow and transport | The groundwater inflows and outflows can be given as inputs (off-line coupling) or can be supplied by a coupled groundwater model (on-line coupling) to model feedback. | Groundwater model, PITLAKQ |
erosion (mass input) | Precipitation and wind waves move material into the lake. | PITLAKQ |
erosion (water quality impact) | Eroded material effects lake water quality by adding dissolved substances and cation exchanger loadings that release substances. | PHREEQC, PITLAKQ |
algae and nutrients | Algae grow depending on temperature, available light and nutrients. C has been added as limiting nutrient. | CE-QUAL-W2, PITLAKQ |
chemical lake reactions | Equilibrium and kinetic reactions in all model cells. Organic matter from biological process is used as electron donators (linking chemical and biological reactions). | PHREEQC, PITLAKQ |
mineral precipitation | Forming minerals can be allowed to precipitate. | PHREEQC, PITLAKQ |
sediment release | Sediment at lake bottom can release substances. Release rates can be given as function of time or can depend on current lake water composition. | PITLAKQ |
treatment | Substances can be added to the lake at any defined location with a time-variable scheme. | PITLAKQ |
alkalinity of sinks and sources | In a post-processing step the alkalinity contributions of sinks and sources can be determined with a monthly time step. | PITLAKQ |
coupling of all processes | All processes can use information generated by other processes. For example, lake water temperature is used in chemical reactions. | PITLAKQ |
process additions / modifications | The model implementation is modular and allows for addition or modification of processes according to site specific needs. | PITLAKQ |
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