WetQual
(https://github.com/SFWS-HydrologyLab/WetQual)
(https://github.com/USEPA/WetQual-GUI)
Wetland Water Quality Model (WetQual):
WetQual is a process-based model which simulates hydrologic processes as well as N, P, total suspended sediment (TSS) and C cycles and their dynamics in natural and constructed wetlands (Hantush et al. 2013; Kalin et al. 2013; Sharifi et al. 2013, 2015, 2017). The model has been developed through a joint research collaboration between Auburn University (Dr. L. Kalin) and the U.S. EPA Office of Research and Development (Dr. Mohamed M. Hantush).
WetQual partitions a wetland into three basic compartments: (1) (free) water column, (2) wetland soil layer, which is further portioned into aerobic and anaerobic zones, and (3) plant biomass (Hantush et al., 2013). The model simulates oxygen dynamics and the impact of oxidizing and reducing conditions on nitrogen transformation and removal, and approximates phosphorus precipitation and releases into soluble forms under aerobic and anaerobic conditions, respectively. Processes in surface water and the bottom-active soil layer are described by a system of coupled ordinary differential equations (Hantush et al., 2013). The model runs on daily time scale, while the model internally divides the one-day time interval into a smaller time interval for numerical integration.
There are three different versions of the model: (1) ponded and lumped (Hantush et al. 2013; Kalin et al. 2013); (2) ponded and compartmental (Sharifi et. al. 2015); and (3) variably saturated (Sharifi et. al. 2017):
Model #1 partitions a wetland into three basic compartments: (i) (free) water column, (ii) wetland soil layer (which is further partitioned into aerobic and anaerobic zones), and (iii) plant biomass.
Model #2 improves on the spatial resolution of model #1 in order to help users capture the spatial variability when active and passive zones are present in a wetland. Models #1 and #2 are suited for modeling nutrient dynamics in continuously ponded wetlands, i.e., they do not track water content and nutrients outside the ponded part of wetlands.
Model #3 was developed to simulate nutrient cycling and biogeochemical reactions in both ponded and unsaturated wetland zones (consider wetland expansion and shrinking).
WetQual Graphical User Interface (GUI):
A Graphical User Interfaces (GUI) was developed for WetQual. The GUI enables users with a basic knowledge of hydrology and water quality to easily apply the WetQual model to their wetland sites and related projects. The GUI reads in input forcings (i.e., climate/weather, runoff and nutrient loading) and geometry table (i.e., depth-area-volume-outflow relationship) to calculate wetland outflow, reference depth of water in wetland, wetland surface area and volume of wetland surface water.
The GUI allows the WetQual model to be run either in a deterministic or stochastic mode. In the stochastic mode, users need to select the probability distributions (uniform, log-normal or triangular) and relevant statistics for each model parameter. The GUI generates random parameter sets and performs Monte Carlo Simulations (MCS) to generate ensemble of outputs.
The GUI provides an opportunity to visualize both deterministic and stochastic model outputs through series of graphs. With the latter, users can visualize the time series of various WetQual outputs for a particular parameter set. Alternatively, GUI can also summarize the ensemble of model runs through prediction intervals.
If observed data are available, the GUI can also perform Generalized Likelihood Uncertainty Estimation (GLUE) (Beven and Freer, 2001) and Bayesian Monte Carlo simulation and maximum likelihood estimation (BMCML) analyses where users can perform uncertainty analyses (Hantush and Chaudhary, 2014).
Please explore and download WetQual model from https://github.com/USEPA/WetQual-GUI.