-Science Beneath the Surface-

Water moves, even deep beneath the surface.

Where does the rain go after it seeps underground? How do fresh water and seawater mix beneath the coast? When and how are nitrates decomposed? This blog aims to reproduce these "invisible movements of water" inside a computer.

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MODFLOW / SEAWAT
The industry-standard simulator for solving groundwater flow numerically. It calculates flow based on Darcy's law, density-driven convection, and even tidal effects. Essential for analyzing the Ghyben-Herzberg interface and SGD in coastal areas.
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PHREEQC
The engine for geochemical calculations. It solves the "chemistry of water" at the level of reaction equations—chemical reactions between water and rock, saturation indices of mixed waters, and the progression of denitrification.
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Python（FloPy・PhreeqPy）
The glue that connects the two. Fully automates everything from grid generation and boundary condition setup to result visualization. Change one line of parameter, and another scenario runs instantly.
Themes
Formation of the freshwater-seawater interface in the Ryukyu limestone aquifer
Rock-water interaction analysis (under varying conditions of solution concentration, temperature, etc.)
Groundwater nitrate contamination and denitrification diagnosis
Limestone dissolution potential analysis by mixing corrosion

This blog is not a place to present completed research results, but a record of trial and error. The story of when the code didn't work, the hesitation in deciding parameters, the process of struggling with corrections using Vibe Coding—I will write down these "processes" as much as possible.

🌊 Groundwater Series

Practical know-how for analyzing groundwater flow with MODFLOW and FloPy.

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⚗️ Geochemistry Series

Modeling water quality and geochemical reactions using PHREEQC and Python.

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