Hydraulic Erosion

Simulate simulate.hydraulic

Rivers carve branching valleys over geological time and drop their sediment where they slow down. Strength limits where it acts; hardness resists wear. Water leaves at the world's edges.

Output with default settings, rendered by LibreTerrain.

Inputs

Port	Type
Terrain	Heightfield
Strength	Mask	Optional
Rock hardness	Mask	Optional

Outputs

Port	Type
Height	Heightfield
Flow	Mask
Wear	Mask
Deposition	Mask
Sediment	Mask

Settings

Setting	Default	Range / options	Description
Duration	1,000 kyr	0 to 5,000 kyr	Time simulated, in thousands of years. Zero leaves the terrain unchanged.
Rainfall	1 m/yr	0 to 10 m/yr	Yearly rainfall. More rain makes bigger rivers that cut faster.
Rock softness	0.5	0 to 1	How easily rivers wear the rock; multiplied by 1 - hardness.
Sediment capacity	1.5	0 to 10	How much sediment a river can carry, relative to what it erodes. Lower values leave more sediment in valleys.
Deposition	0.5	0 to 1	Share of the excess sediment that settles per 100 m of flow. 0 = never settles.
Evaporation	0.02	0 to 1	Share of the water lost per kilometre it flows.
Downcutting	1	0 to 4	Multiplier on river erosion. Zero stops new wear.
Detail size	8 m	1 to 1,000 m	Cell size the rivers are simulated at, in metres: about the width of the smallest valleys. Smaller is slower. The result is the same at any preview or build resolution.
Hillslope creep	0.002 m²/yr	0 to 1 m²/yr	Soil creep that rounds hillslopes and smooths small rills between rivers.

Notes

Hydraulic Erosion is usually the slowest node in a graph. Keep the preview resolution low while you tune it; because every setting is in metres and years, the full-resolution build gives the same landforms with more detail.

A common chain is Hydraulic Erosion → Thermal Erosion: water carves the valleys, then thermal erosion adds scree below steep faces. The bundled Scottish Highlands example uses exactly this.

See also

Lakes · Rivers · Sea · Snow · Thermal Erosion