Geology

geology loads geological zones as vector or raster data. HydroModPy can use those zones as display layers, mesh constraints, field supports, and keys for hydraulic-property transfer.

Accepted sources

Source	Use when	Source page
custom	A local geology layer and code field are authoritative.	custom
brgm_1m	The public 1:1,000,000 BRGM geology layer is the intended regional support.	brgm-1m
brgm_50k	The public 1:50,000 BRGM geology layer is available and the study needs finer geological structure.	brgm-50k

Minimal example

[data]
types = ["geology"]

[[data.geology.sources]]
source = "brgm_1m"
extent = "watershed"

Loaded shape

The loaded object should preserve zone geometries and a stable geology code. When values_table_path is provided, the code also becomes the join key for hydraulic-property tables.

Visual check

The map is not enough without its legend: the displayed categories must remain interpretable after clipping, reprojection, and optional property joins.

Property transfer check

Fig. 142 This generated data-doc case starts from a versioned BRGM-style geology vector, joins a local property table, rasterizes the geology support on a mesh, and displays the resulting K field. It is the most direct documentation proof that geology can become a solver-facing parameter support instead of remaining a background map.

Geology becomes solver-relevant when zones are transferred to hydraulic properties or model supports. Use this kind of figure to verify that the geology code has not collapsed into a single default category.

Downstream uses

• geology maps in data overviews;

• mesh constraints and interfaces;

• support selection for fields;

• hydraulic conductivity, storage, or zone-based parameterization.

Geology Source: brgm_1m

Use source = "brgm_1m" for a public regional geology support. It is a good default when the model needs broad geological differentiation without the complexity of a finer map.

Minimal example

[[data.geology.sources]]
source = "brgm_1m"
extent = "watershed"

Operational checks

• The selected extent should cover the future mesh or property support.

• The clipped layer should keep readable categories and a usable legend.

• If properties are transferred from geology, verify the resulting parameter map rather than assuming every BRGM code has a property.

Expected figure

Use the geology overview panel first, then the geology-driven conductivity transfer figure when the layer feeds hydraulic parameters.

Geology Source: brgm_50k

Use source = "brgm_50k" when the available public 1:50,000 geology layer is appropriate for the study scale and the project benefits from finer geological detail.

Minimal example

[[data.geology.sources]]
source = "brgm_50k"
extent = "study_area"

Operational checks

• Finer geology can introduce many small interfaces. Check mesh size and interface count before activating every boundary as a constraint.

• The legend should remain readable after clipping.

• Property-table coverage is more important at fine scale because missing categories can become spatially fragmented.

Expected figure

Use a map panel to inspect categories, then a mesh or property-transfer figure to decide whether the detail is useful or too noisy for the model objective.

Geology Source: custom

Use source = "custom" when a local geology vector or raster is the reference for the project.

Minimal example

[[data.geology.sources]]
source = "custom"
path = "data/geology/geology.gpkg"
code_field = "CODE_LEG"
values_table_path = "data/geology/hydraulic_properties.csv"

Operational checks

• code_field must exist in the local layer and remain non-empty after clipping.

• values_table_path should use the same geology codes when properties are joined.

• CRS and geometry validity matter because geology can constrain meshes.

• Empty or unlabeled legend categories usually mean the code field or property join is wrong.

Expected figure

Inspect the geology panel with its legend, then inspect any derived hydraulic-property transfer figure before trusting the layer in a model.