Texas Tech University

EDYS Linkages

Linking two or more models together is one effective way to maximize the benefits of each.  Since no single model can simulate all the processes in an ecosystem at the highest level, every model simulates some processes more accurately than other processes.  Linking two models with different strengths allows the user to gain from what each model does well and overcome the weaknesses of each, as well.

The EDYS model has been linked with several other models through the years, as described below.


TUDM (Training Use Distribution Model) – EDYS was linked with this military training model at Fort Hood in central Texas.  The objective with this linkage was to more accurately assess impacts on the vegetation by various military training exercises.  No report of this linkage is available.


HSPF (Hydrological Simulation Program – Fortran) – EDYS was linked with HSPF in the Cibolo Creek watershed of central Texas.  This watershed lies on the northern boundary of San Antonio and is occasionally subjected to major floods.  The models were linked for EDYS to provide more accurate values of surface runoff and soil moisture for simulation of stream flows in HSPF, with the intent of developing better management plans for dealing with flooding.

Price, D., T. McLendon, and C. Coldren. 2004. Application of an ecological model for the Cibolo Creek watershed. U.S. Army Corps of Engineers, Vicksburg, Mississippi. Water Quality Technical Notes Collection ERDC WQTN-CS-04.


MODFLOW (Modular finite-difference flow model) – MODFLOW is the standard for simulating groundwater movements.  It was linked with EDYS to simulate the effects of changes in the water table on roots (and the uptake of water), as well as the impacts of water uptake by roots on the water table level.  No reports are available for this linkage.


GSSHA (Gridded Surface Subsurface Hydrologic Analysis) – GSSHA is effective at simulating overland flow during rainfall events, as well as the degree of erosion resulting from runoff.  EDYS was linked with GSSHA to demonstrate the impacts of fine-scale temporal and spatial variability in surface runoff on vegetation.

Johnson, B. E., and C. L. Coldren. 2006. Linkage of a physically based distributed watershed model and a dynamic plant growth model. U.S. Army Corps of Engineers, Vicksburg, Mississippi. Technical Report ERDC/EL TR-06-17.


HYDRUS-2D – this model is used for simulating the flow of water, heat, and solutes in variably saturated media.  EDYS was linked with HYDRUS-2D to obtain more accurate soil moisture levels, and the resulting effects on vegetation dynamics.  No report is available.


TELEMAC – this model simulates the free surface flow of water.  For the linkage with EDYS, TELEMAC was applied to San Antonio Bay in order to more accurately simulate depth and salinity within the bay.  It supplied data on depth and salinity to EDYS in order to evaluate the potential impacts of changes in bay circulation on vegetation in the estuaries around the bay.

Coldren, C., A. Asadi, T. Cleveland, and K. Rainwater.  2020.  Coupling EDYS and TELEMAC-2D for ecohydrological and hydrodynamic simulation of San Antonio Bay.  Report prepared for San Antonio River Authority. Texas Tech University, Lubbock, Texas. 61 p.