1. dentric streams/rivers/canal/open channel,
2. overland regime (land surface),
3. subsurface media (vadose and saturated zones), and
4. ponds, lakes/reservoirs (small/shallow).

It also includes control structures such as weirs, gates, culverts, pumps, levees, and storage ponds and managements such as operational rules for pumps and control structures. The WASH123D code consisted of eight modules to deal with multiple media:

1. 1-D River/Stream Networks,
2. 2-D Overland Regime,
3. 3-D Subsurface Media (both Vadose and Saturated Zones);
4. Coupled 1-D River/Stream Network and 2-D Overland Regime,
5. Coupled 2-D Overland Regime and 3-D Subsurface,
6. Coupled 3-D Subsurface and 1-D River Systems;
7. Coupled 3-D Subsurface Media, 2-D Overland, and 1-D River Network; and
8. Coupled 0-D Shallow Water Bodies and 1-D Canal Network.

For any of the above eight modules, flow only, transport only, or coupled flow and transport simulations can be carried out using WASH123D.

1. Geomety in terms of finite element mesh
2. matreial properties,
3. initila conditions,
4. boundary conditions,
5. meteogoligcal data, and
6. reaction networks for biogeochemical transport.

Detailed input/output refers to Yeh et al., 2005 Technical Report on WASH123D

1. hydrological cycles (evaporation, evapotranspiration, infiltration, and recharges);
2. fluid flow (surface runoff in land surface, hydraulics and yydrodynamics in river/stream/canal networks;
3. interflow in vadose zones, and groundwater flow in saturated zones);
4. salinity transport and thermal transport (in surface waters and groundwater);
5. sediment transport (in surface waters);
6. water quality transport (any number of reactive constituents);
7. biogeochemical cycles (nitrogen, phosphorous, carbon, oxygen, etc.); and
8. biota kinetics (algae, phyotoplankton, zooplakton, caliform, bacteria, plants, etc.).

1. flows rivers/stream/canal/open channel networks - 1D St Venant Equations for River Networks with kinematic, diffusive, and fully dynamic wave options,
2. flows in overland regime - 2D St Venant Equations with: kinematic, diffusive, and fully dynamic wave options,
3. flow in subsurface media - 3D Richard Equation for both vadose and saturated zones,
4. salinity, thermal, and sediment transport in river networks and overland regime - modified ddvection-dispersion equations with phenomenological approaches for erosion and deposition, and
5. water quality transport for all media - advection-dispersion-reaction equations with reaction-based mechanistic approaches to water quality modeling using a general paradigm.

For details refer to Yeh et al., 2005 Technical Report on WASH123D

1. verify the correctness of computer implementation,
2. demonstrate the need of various numerical options and coupling strategies between transport and biogeochemical processes for application-depending circumstances,
3. illustrate how the generality of the water quality modeling paradigm embodies the widely used water quality models as specific examples; and
4. validate the capability of the models to simulate laboratory experiments, and indicate its potential applications to field problems.

1. Flooding of Dade County watershed in South Florida,
2. Flooding of South Fork Broad River Watershed in South Carolina due to Hurricane Earl,
3. Redistru=ibution of waters in a wetland watershed along Biscayne Bay Coast Wetlands.

For Laboraty Test:

1. Circular Dam Break problems,
2. two dimensional non-symmetrical dam break problem, and
3. Constructed storm water treatment area.

I am willing to collaborate with any users either in the further development and modification of the model or in the application of the model to field scale or laboratory scale problems. I am also willing to collaborate with anyone to develop graphical interfaces to prepare input and to visualize output of this model.

• Yeh, G. T., G. Husng, H. P. Cheng, F. Zhang, H. C. Lin, E. Edris, and D. Richards, 2005. A First principle, Physics based Watershed Model: WASH123D. Chapter 9 in Watershed Models (V. P. Singh and D. K. Frevert, ed.), CRC Press LLC, 6000 Broken Sound Parkway, NW, (Suite 300) Boca Raton, FL 33487, USA. pp. 211-244.
• Huang, G. B. and G. T. Yeh, 2008. A Comparative Study of coupling Approaches for Surface water and groundwater interactions. Journal of Hydrologic Engineering, ASCE (in press).
• Huang, G. B., and G. T. Yeh, 2008. Two-dimensional Dynamic Wave Flow Modeling using A Characteristics-based Method. Journal of Hydrologic Engineering, ASCE (in press).
• Zhang, F., G. T. Yeh, J. C. Parker, S. C. Brooks, M. N., Pace, Y. J. Kim, and P. M. Jardine, 2007. A reaction-based paradigm to model three-dimensional reactive chemical transport in groundwater. J. Contaminant Hydrology. Volume 93, 10-32.
• Zhang F., G. T. Yeh, J. C. Parker, and P. M. Jardine, 2008. A reaction-based river/stream water quality model: Model development and numerical schemes. Journal of Hydrology. Vol. 348, 496– 509.
• Yeh, G. T., G. B. Huang, F. Zhang, H. P. Cheng, and H. C. Lin, 2005. WASH123D: A Numerical Model of Flow, Thermal Transport, and Salinity, Sediment, and Water Quality Transport in WAterSHed Systems of 1-D Stream-River Network, 2-D Overland Regime, and 3-D Subsurface Media. A Technical Report Submitted To EPA. Dept. of Civil and Environmental Engineering, University of Central Florida, Orlando, FL 32816.Download WASH123D Technical Report]]

1. every module was developed based physics-based conservation principles of fluid, momentum, enery, and mass;
2. rigious coupling processes between media to internalize fluxes across media boundaries,
3. general paradigm to model water quality based on reactive biogeochemistry,
4. many numerical options were implemented.

I have already posted the technical report. For those who are interested in "true" physics-based watershed models, please read the report and I hope you like it.