GRLP: gravel-river long-profile evolution

GRLP simulates the long-profile evolution of alluvial river valleys formed and reworked by gravel-bedded rivers, from single channels to full drainage networks. It solves a physically based, transport-limited sediment-conservation equation (Wickert & Schildgen, 2019) with a semi-implicit numerical scheme.

Key assumptions:

• The river’s bed and banks are noncohesive gravel, and the rate and form of the river’s evolution is limited by its ability to move that gravel (transport-limited).

• The channel maintains a self-formed, near-threshold equilibrium width with mobile gravel banks (Parker, 1978), which linearizes the transport response to changing discharge. Engineered or bedrock-walled rivers need a fixed width set by other dynamics.

• Evolution is driven by a single channel-forming (bank-full) discharge acting for an intermittency fraction of the time (Blom et al., 2017).

• Aggradation and incision act across the whole valley bottom — the area over which material must be added or removed for the bed to change elevation.

Contents

• Installation
  • From PyPI (release)
  • From source (development install)
  • Verifying the install
  • Building these docs locally
• Quickstart
  • A single long profile
  • A river network
• Interactive demo
• Theory and governing equations
  • Symbols
  • Sediment transport
  • Mass conservation (Exner)
  • Long-profile evolution equation
  • Boundary conditions
  • Numerical method
  • Steady-state and slope–area
  • Linearized response: gain and lag
  • The 2020 corrigendum
  • Networks
• Network solver: global assembly by walking the topology
  • What changed, and why
  • Global node numbering
  • Assembly: local stencil → global sparse matrix
  • The stencil is the single-segment stencil
  • Confluences: a conservative junction cell
  • Structure of the resulting matrix
  • Relation to standard methods
  • Time stepping
• Numerical accuracy: time stepping
  • How the accuracy is measured
  • What the figure says
  • Choosing a time step
  • Second order in time: BDF2 (the default)
  • Iterating the solve to convergence (the default)
  • Adaptive time stepping (opt-in)
• Examples
  • Getting started
  • One-dimensional (examples/one_dimensional/)
  • Networks (examples/network/)
  • Spectral response (examples/McNab_et_al_GRL/)
  • Deprecated (examples/deprecated/)
• API reference
  • Which object do I use?
  • grlp.grlp
  • grlp.solver
  • grlp.build_synthetic_network
• Citing GRLP
  • Always
  • Linearization and spectral response
  • Networks
• References
  • GRLP papers
  • Selected supporting literature

Tutorials

• Examples of using GRLP
• GRLP river networks: a 5-segment example
• GRLP random networks: generate and analyze at scale

Where things live

• grlp/ — the package: grlp.py (the Segment, LongProfile, and Network classes, equations, and analysis), solver.py (the network sparse-matrix solver), and build_synthetic_network.py (random-network generation).

• examples/ — runnable, curated example scripts (see Examples).

• preprocessing/ — an optional input-cleaning step that turns network geometry (e.g. extracted from a DEM) into GRLP inputs; run before GRLP, not part of it.

Indices

• Index

• Module Index