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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.

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Processes of the model PITLAKQ
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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