Detour Lake Mine Preliminary Water Balance Assessment

Author: Isaiah Ephraim Affiliation: B.Eng Mining Engineering, Federal University of Technology, Akure, Nigeria Contact: isaiahephraim04@gmail.com Profile: Academia.edu | LinkedIn | GitHub

This repository contains the Python code used to compute, tabulate, and visualise the preliminary water balance for the Detour Lake open pit mine in northeastern Ontario, Canada.

The analysis is the computational basis for:

Ephraim, I.G. (2026) Preliminary Water Balance Assessment for a Large Open Pit Mine: A Case Study of Detour Lake Mine, Ontario, Canada. Zenodo. [DOI to be added on publication]

Groundwater inflow values are taken from the companion study:

Ephraim, I.G. (2026) Steady-State Groundwater Inflow Estimation for Large Open Pit Mining Operations: Analytical Radial Flow Assessment — Detour Lake Mine, Ontario, Canada. Zenodo. https://doi.org/10.5281/zenodo.19111972

All input data are derived from publicly available sources. No proprietary mine data were used or required.

Running detour_lake_water_balance.py produces:

• Annual water balance summary for two groundwater scenarios
• Full monthly water balance table (Scenario 1 — conservative)
• Sensitivity analysis table (three parameters, six variations)
• Figure 1 — monthly inflow/outflow bar chart with cumulative storage line
• Figure 2 — horizontal bar chart of sensitivity results

Python 3.8 or later is required.

Install dependencies:

pip install numpy matplotlib

No other packages are needed.

Run the script from the command line:

python detour_lake_water_balance.py

All results print to the terminal. Two PNG figures are saved in the current directory:

• figure1_monthly_balance.png
• figure2_sensitivity.png

All input parameters are defined at the top of the script under clearly labelled sections. To update a value, change it in that section — the rest of the calculations update automatically.

The most important parameters to verify before submission are:

Two scenarios are carried forward from Ephraim, I.G. (2026):

To run the monthly balance for Scenario 2, change the gw_scenario argument in the print_monthly_table() and plot_monthly_balance() calls at the bottom of the script.

Seasonally, the system runs at deficit for ten months. April delivers the peak monthly inflow — approximately 1.506 Mm³ under baseline conditions, representing 43% of total mine water pond capacity in a single month.

detour_lake_water_balance.py      Main script — all calculations and figures
README.md                         This file
figure1_monthly_balance.png       Generated on first run
figure2_sensitivity.png           Generated on first run

Every number in the companion paper can be reproduced by running the script with default parameters. The script is self-contained — no external data files are required because all input values are hard-coded with their sources documented inline.

• Evaporation uses a simplified temperature-based estimate. The full Penman equation with NASA POWER solar radiation and humidity data at 50.02°N, 79.72°W should be applied before final submission.

• Pit surface area uses a circular approximation based on the equivalent radius from Ephraim, I.G. (2026). Verify against the actual pit shell from the NI 43-101 before detailed design work.

• Monthly temperature distribution is interpolated from January and July averages. Monthly ECCC station records would improve precision.

• TMA seepage is estimated from published literature ranges because no quantitative measurements were reported in the 2018 Technical Report.

These limitations are consistent with the preliminary scope of the assessment and are discussed in full in the companion paper.

1. Detour Gold Corporation, 2018. NI 43-101 Technical Report on the Detour Lake Mine, Ontario, Canada. Effective date: 27 June 2018.
2. Ephraim, I.G., 2026. Steady-state groundwater inflow estimation for large open pit mining operations. Zenodo. https://doi.org/10.5281/zenodo.19111972
3. Environment and Climate Change Canada, 2023. Canadian climate normals. Available at: https://climate.weather.gc.ca [Accessed: March 2026].
4. NASA, 2023. POWER climatology resource for agroclimatology. Available at: https://power.larc.nasa.gov [Accessed: March 2026].
5. Chow, V.T., Maidment, D.R. and Mays, L.W., 1988. Applied Hydrology. New York: McGraw-Hill.
6. Freeze, R.A. and Cherry, J.A., 1979. Groundwater. Englewood Cliffs, NJ: Prentice-Hall.

If you use this code, please cite:

Ephraim, I.G. (2026) Preliminary Water Balance Assessment for a Large Open Pit Mine: A Case Study of Detour Lake Mine, Ontario, Canada. Zenodo. [DOI to be added on publication]

MIT License. See LICENSE file for details.