MODFLOW 6 Version of RGTIHM

This repository contains the MODFLOW 6 conversion of the Rio Grande Transboundary Integrated Hydrologic Model (RGTIHM). The original model was developed using MODFLOW-One Water Hydrologic Model (MF-OWHM) by the USGS.

USGS Study:

Step 1: Set Up the Project Directory

Before downloading any files, create a working directory:

mkdir MF6
cd MF6

Clone the repository:

git clone git@github.com:mabdazzam/rgtihm.git

or

git clone https://github.com/mabdazzam/rgtihm.git

Step 2: Download and Extract the MF-OWHM Model

Go to the ScienceBase-Catalog page and download all the files for RGTIHM MF-OWHM Model:

The downloaded files include:

• SIR2022-5045Thumbnail.jpg
• ancillary.zip
• bin.zip
• georef.zip
• model.zip
• output.zip
• source.zip
• modelgeoref.txt
• readme.txt

Create a directory for MF-OWHM files and move them:

mkdir owhm
cd owhm
mv ~/Downloads/{SIR2022-5045Thumbnail.jpg,ancillary.zip,bin.zip,georef.zip,model.zip,output.zip,source.zip,modelgeoref.txt,readme.txt} .

Extract all the zipped files:

for i in *.zip; do unzip "$i"; done

Step 3: Run the Conversion Notebook

Navigate to the MF6 directory and launch Jupyter Lab:

cd ..
jupyter lab

Open and run rgtihm.ipynb to convert the MF-OWHM model into MODFLOW 6 format.

Step 4: Run the Converted MODFLOW 6 Model

Once the model is created, navigate to the model directory:

cd model

Run the model using the MODFLOW 6 executable:

If the mf6 executable is located in /usr/local/src/modflow6/bin/, run:

~/usr/local/src/modflow6/bin/mf6

If mf6 is installed in the system path, simply run:

mf6

Step 5: Parallel Simulation (Optional)

To generate submodels for parallel execution, run all cells in splitting.ipynb.
This will create submodels in the splitmodels/ directory.

Run the submodels in parallel using:

mpiexec -np 4 ~/usr/local/src/mf6/bin/mf6 -p

Replace 4 with the number of submodels.

Note: Parallel notebook and parallel simulation is no longer valid for RGTIHM.

Models with HFB packages cannot be split with Mf6Splitter.

The notebook was written and tested before importing the HFB package from RGTIHM OWHM.

Troubleshooting: Indexing Errors in WEL and GHB

Errors in WEL and GHB may occur due to indexing differences between MF-OWHM and MODFLOW 6:

• MODFLOW 6 indexing starts from xorigin (xll) and yorigin (yll).
• MF-OWHM indexing starts from xul and yul.

This difference can cause wells and GHB points to fall outside the active model area. Adjusting the indexing will resolve the issue.