CCHE3D-GW

CCHE3D-GW is a three-dimensional finite element model which can be used to simulate the variably-saturated groundwater flow. The mix-formed Richards equation was used as the governing equation. This model was based on the framework of CCHE3D, which is a surface water dynamic model developed by National Center for Computational Hydroscience and Engineering (NCCHE). In CCHE3D-GW, the mesh structure is the same as that in CCHE3D, so they are naturally compatible with each other, which will facilitate the future integrating work of SW and GW models.

The model features the following capabilities:

• It can simulate variably-saturated GW flows because it uses the Richards equation (Richards 1931) as its governing equation. Thus, it can handle GW flows in both fully- and partially-saturated soils, i.e., the vadose zone has been considered in this model.

• CCHE3D-GW can handle various boundary conditions for GW flows, such as active wells (pumping or injection), general-head condition and flux boundary condition.

• In the present version of CCHE3D-GW, the SW dynamics, such as stream flow and 3infiltration, are considered as boundary conditions. Consequently, the GW-SW interactions are simulated by simplifying the SW flows as head or flux boundary conditions. Although CCHE3D-GW has not been integrated with our SW models (CCHE2D/3D), the structure of the mesh is the same as the one used in CCHE2D/3D, which will make it easier to integrate these SW and GW models in the future.

• For the simulation of GW-SW interactions, CCHE3D-GW can consider time-varying streambed conductivity, which is commonly encountered during flooding events (Korus et al., 2020; Levy et al., 2011; Mutiti and Levy, 2010; Zhang et al., 2011). This capacity is new for a GW numerical model.

The following examples represent some of the problems for which CCHE3D-GW has been designed:

1)  Pumping in a multiple-layer aquifer is frequently encountered in real-world problems. The newly developed CCHE3D-GW has been verified in a three-layer aquifer system, which is located in the Titusville/Mims area. With these results, the impacts from pumping on the regional aquifers can be studied.

2)  Infiltration often occurs in the real-world problems. The infiltrated the surface water can supply the subsurface water resources as well as affect the groundwater quality. As a result, it is imperative to simulate this hydrological process accurately. The newly developed CCHE3D-GW has been verified with the simplified 1-D infiltration in an unsaturated soil column. Good agreement can be found between the simulated infiltration front with the previous result (Zhang and Ewen, 2000), indicating the capability of the model.

3)  Pumping in an unconfined aquifer is usually involved with the vadose zone. The newly developed CCHE3D-GW has been verified with a hypothetical pumping in a rectangle-unconfined aquifer. The simulation results are compared with the ones simulated by VSAFT3 (Mao et al., 2011). As evident from the figure below, we see good results from the two representative observation wells.

4)  A single-well pumping/injection in an unconfined aquifer in which the vadose zone is considered.

The following links provide video examples of post-processing of the results:

DOWNLOADS:

CCHE3D-GW (Windows x86_64, Zipped)

CCHE3D-GW User Manual v1.0 (PDF)

CCHE3D-GW Quick Start Guide (PDF)

CCHE3D-GW Input files for Quick Start Guide (Zipped)

Note: Please be aware that CCHE3D-GW has not been incorporated into the CCHE GUI interface at this time. Users only need to download ZIP archive of the executable file ‘CCHE3D-GW-beta.exe’ and then copy that into the input file folder to run the simulation. We understand that this is not user-friendly, and we are working on building the user interface. We will gradually improve the model based on your experiences, so your comments and feedback will be much appreciated. If you have any questions and/or bug reports, please contact the developer, Jiayu Fang, via email at jfang@ncche.olemiss.edu