The Ghent–Terneuzen Canal is a semi-enclosed brackish-water system in which corrosion is harder to predict than in the open sea. A corrosion model averaged over the full canal length risks masking the real spatial variation. This study investigates whether the monitoring locations can be grouped on the basis of their biofouling composition, whether the water parameters separate those groups statistically, and whether the mass loss per zone can be described with a power-law model. Using the COMIC dataset, comprising nine months of fouling, water-parameter and massloss measurements on S235 steel coupons, the locations were divided through exploratory visualisation into three zones: hard fouling (north), transition, and soft fouling (south). This partition was tested with a Wilcoxon rank-sum test with Bonferroni correction, a principal component analysis, and a power-law modelling of the mass loss. Conductivity separates the zones most consistently; ORP, pH and dissolved oxygen support this in particular months. The PCA confirms the separation along PC1. The mass loss follows a power law per group with an exponent below 0.5, consistent with diffusion-limited corrosion, but within nine months the group parameters are statistically barely distinguishable. The canal proves to consist of three biogeochemical zones; a longer monitoring period and hierarchical models are required to distinguish the corrosion per zone more sharply.