landlab

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Landscape evolution and surface process modelling in Python. Build 2D numerical models for erosion, hydrology, soil transport, and geomorphology. Use when Claude needs to: (1) Model landscape evolution over time, (2) Simulate river/stream erosion, (3) Route water flow across terrain, (4) Model hillslope diffusion processes, (5) Simulate weathering and soil production, (6) Analyze drainage networks, (7) Combine multiple geomorphic processes, (8) Load/save DEM data for modeling.

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npx skill4agent add steadfastasart/geoscience-skills landlab

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landlablandscape-evolutionsurface-process-modellingdem-processingpython-geomorphology

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Landlab - Surface Process Modelling

Quick Reference

python
from landlab import RasterModelGrid
from landlab.components import FlowAccumulator, StreamPowerEroder
import numpy as np

# Create grid
grid = RasterModelGrid((100, 100), xy_spacing=10.0)
z = grid.add_zeros('topographic__elevation', at='node')
z += np.random.rand(grid.number_of_nodes) * 0.1

# Set boundaries (open bottom edge)
grid.set_closed_boundaries_at_grid_edges(True, True, True, False)

# Create and run components
fa = FlowAccumulator(grid, flow_director='D8')
sp = StreamPowerEroder(grid, K_sp=1e-5)

for _ in range(100):
    fa.run_one_step()
    sp.run_one_step(dt=1000)
    z[grid.core_nodes] += 0.001 * 1000  # Uplift

grid.imshow('topographic__elevation', cmap='terrain')

Grid Types

GridUse Case
RasterModelGrid
Regular rectangular grids (most common)
HexModelGrid
Hexagonal grids (isotropic flow)
VoronoiDelaunayGrid
Irregular point distributions
NetworkModelGrid
Channel networks only

Key Concepts

Fields and Boundaries

python
# Fields: data stored at grid elements (nodes, links, cells)
z = grid.add_zeros('topographic__elevation', at='node')
grid.at_node['drainage_area']  # Access existing field

# Boundaries: close all edges except outlet
grid.set_closed_boundaries_at_grid_edges(True, True, True, False)
z[grid.core_nodes] += uplift * dt  # Core nodes exclude boundaries

Essential Operations

Flow Routing

python
from landlab.components import FlowAccumulator

fa = FlowAccumulator(grid, flow_director='D8')  # or 'Steepest', 'MFD'
fa.run_one_step()
drainage_area = grid.at_node['drainage_area']

Stream Power Erosion

python
from landlab.components import StreamPowerEroder

sp = StreamPowerEroder(grid, K_sp=1e-5, m_sp=0.5, n_sp=1.0)
sp.run_one_step(dt=1000)  # dt in years

Hillslope Diffusion

python
from landlab.components import LinearDiffuser

ld = LinearDiffuser(grid, linear_diffusivity=0.01)  # m^2/yr
ld.run_one_step(dt=100)

Load/Save DEM Data

python
from landlab.io import read_esri_ascii, write_esri_ascii
from landlab.io.netcdf import read_netcdf, write_netcdf

grid, z = read_esri_ascii('dem.asc', name='topographic__elevation')
write_esri_ascii('output.asc', grid, names='topographic__elevation')
write_netcdf('output.nc', grid)  # Save all fields

Multi-Component Model

python
from landlab import RasterModelGrid
from landlab.components import FlowAccumulator, StreamPowerEroder, LinearDiffuser

grid = RasterModelGrid((100, 100), xy_spacing=100.0)
z = grid.add_zeros('topographic__elevation', at='node')
z += grid.node_y / 1000 + np.random.rand(grid.number_of_nodes) * 0.1
grid.set_closed_boundaries_at_grid_edges(True, True, True, False)

fa = FlowAccumulator(grid, flow_director='D8')
sp = StreamPowerEroder(grid, K_sp=1e-5)
ld = LinearDiffuser(grid, linear_diffusivity=0.01)

dt, uplift_rate = 1000, 0.001
for _ in range(500):
    fa.run_one_step()
    sp.run_one_step(dt)
    ld.run_one_step(dt)
    z[grid.core_nodes] += uplift_rate * dt

When to Use vs Alternatives

Use CaseToolWhy
Landscape evolution modellingLandlabModular components, Python-native
Basin-scale stratigraphyBadlandsFocus on sediment deposition and basin fill
Topographic analysis (MATLAB)TopoToolboxMature MATLAB toolkit for DEM analysis
Simple diffusion/erosionCustom numpyFewer dependencies for basic models
Coupled surface-subsurfaceLandlabComponents for hydrology + geomorphology
Channel network extractionLandlab or pyshedsBoth handle flow routing well
Soil production and transportLandlabDedicated weathering and soil components
Teaching geomorphologyLandlabClear component API, good tutorials
Choose Landlab when: You need a modular, component-based framework for landscape evolution modelling that combines multiple surface processes (erosion, diffusion, flow routing, weathering) in a single simulation.
Choose Badlands when: Your focus is on basin-scale landscape evolution with emphasis on sediment transport and stratigraphic architecture.
Choose custom numpy when: You only need a simple 2D diffusion or stream power model without the overhead of a full component framework.

Common Workflows

Landscape Evolution Model with Erosion and Uplift

  • Create 
    RasterModelGrid
    with appropriate dimensions and spacing
  • Initialize 
    topographic__elevation
    field (flat + noise, or load DEM)
  • Set boundary conditions (open one edge as outlet, close others)
  • Create 
    FlowAccumulator
    with chosen flow director (D8 or MFD)
  • Create 
    StreamPowerEroder
    with erosion coefficient K_sp
  • Create 
    LinearDiffuser
    for hillslope processes
  • Define time step 
    dt
    and total runtime; choose uplift rate
  • Run time loop: flow routing, erosion, diffusion, then uplift
  • Save snapshots at intervals with 
    write_netcdf()
    or 
    write_esri_ascii()
  • Visualize final topography with 
    grid.imshow()
  • Analyze drainage area and channel profiles
  • Extract river long profiles for steepness analysis

Common Issues

IssueSolution
Flat areas block flowAdd small random noise to initial topography
Boundary effectsEnsure at least one open boundary edge for drainage
Unstable erosionReduce 
dt
or 
K_sp
; check Courant condition
Wrong field nameUse exact Landlab names: 
'topographic__elevation'
, 
'drainage_area'
Memory with large gridsReduce grid resolution or use 
NetworkModelGrid
for channels only

Tips

  1. Set boundaries first - before adding components
  2. Use core_nodes - excludes boundary nodes for operations
  3. Check field names - components expect specific names (e.g., 'topographic__elevation')
  4. Start simple - add components incrementally and verify each

References

  • Components Reference - Available components by category
  • Grids Reference - Grid types and configuration

Scripts

  • scripts/erosion_model.py - Basic erosion model template