There are many ways to work out how exposed a site is to waves, from quick fetch-based models to full spectral wave models and ready-made exposure maps. This guide lists the main ones, what each does and when it fits, so you can pick the right tool for your question. For a detailed side-by-side of WEMo, NOAA's WEMo and SWAN, see how WEMo compares.
| If you need to… | Look at |
|---|---|
| Compare wave exposure across many sites in a bay, estuary or lake, quickly | Fetch-based models: WEMo, the USGS Wind Fetch and Wave Models, waver |
| Script an analysis in R with your own shoreline, depth and wind | NOAA's WEMo R package, waver, fetchR, lakefetch |
| Model swell, currents, open coasts or design wave conditions in detail | Spectral models: SWAN, CMS-Wave, MIKE 21 SW; WAVEWATCH III offshore |
| Screen a whole coastline for erosion and flooding exposure | InVEST Coastal Vulnerability |
| Use an exposure layer someone has already made for your region | The datasets below, where they cover your area |
The Wave Exposure Model was published by NOAA in 2007. It now comes in three forms.
Geo Horizons · Free during early access
This site. Draw an area and WEMo fetches depth and hourly wind and returns wave height, wave energy, orbital velocity and bed shear stress for every site, with no data to prepare and nothing to install.
Good for: Screening many sites across a bay, estuary or lake, with maps and a report.
NOAA National Centers for Coastal Ocean Science · Free, open source
NOAA's open-source R version of the Wave Exposure Model, a modernized version of the original ArcMap extension. It runs in R without proprietary GIS software; tutorials are on the project's documentation site.
Good for: Scripted, reproducible analyses in R with your own inputs.
NOAA Office for Coastal Management · Free
NOAA's page for the Wave Exposure Model. The model's formulation and validation are in NOAA Technical Memorandum NOS NCCOS 65 (Malhotra and Fonseca, 2007).
Good for: Background on the model and its uses.
Fetch-based tools measure how far the wind can blow over water toward a site and estimate the waves it raises. They are quick and need little input, which suits sheltered water.
USGS Upper Midwest Environmental Sciences Center · Free (needs ArcGIS with Spatial Analyst)
Calculates wind fetch, significant wave height, length and period, orbital velocity, shear stress and the probability that fine sediment is suspended.
Good for: Habitat rehabilitation projects in lakes and rivers, inside ArcGIS.
Philippe Marchand and David Gill · Free, open source
Calculates fetch along chosen directions and estimates wave energy from wind and wave monitoring data.
Good for: Fetch and wave energy at a set of points in R.
Blake Seers · Free, open source
Calculates wind fetch for points along a coastline in R.
Good for: Fetch lengths as an input to your own exposure index.
rOpenSci · Free, open source
Calculates fetch on lakes in R.
Good for: Lake studies that need fetch for many points.
Spectral models solve the wave energy balance on a computational grid. They take more setting up and computing, and give a fuller picture: swell, currents, design conditions and open coasts.
Delft University of Technology · Free, open source (GPL)
A third-generation wave model for wind-generated waves in coastal regions and inland waters. WEMo's default physics was tuned against SWAN.
Good for: Detailed nearshore wave studies.
NOAA National Centers for Environmental Prediction · Free, source on GitHub
A third-generation wave model developed at NOAA/NCEP, used for ocean and regional wave forecasting.
Good for: Ocean-scale waves and offshore boundary conditions.
U.S. Army Corps of Engineers, Coastal Inlets Research Program · See the project site
The wave model of the Coastal Modeling System, an integrated suite for flow, waves, sediment transport and morphology change in coastal areas.
Good for: Inlets, navigation channels and coastal engineering projects.
DHI · Commercial
DHI's spectral wave module for wave modelling in oceans and coastal areas.
Good for: Consultancy-grade coastal and offshore wave studies.
Tools that combine wave exposure with other factors to answer a planning question.
Natural Capital Project, Stanford University · Free
Uses geophysical and natural habitat characteristics, including wave exposure, to compare how exposed stretches of coast are to erosion and flooding in severe weather.
Good for: Screening a whole coastline for hazard exposure.
The Nature Conservancy, with NOAA scientists · Free
Identifies shorelines with low enough wave energy for living shoreline approaches, in North Carolina's southern Pamlico, Core and Bogue Sounds and the New River Estuary.
Good for: Living shoreline siting in those North Carolina waters.
Exposure layers already calculated for a region. Check the method and resolution suit your question.
Fisheries and Oceans Canada · Free (open data)
Fetch indices and a relative exposure index (REI) combining fetch with modelled wind speeds, as a 35 m GeoTIFF, within 5 km of the coast and shallower than 50 m.
Good for: Nova Scotia and Bay of Fundy coastal studies.
Institute for Marine and Antarctic Studies, University of Tasmania · Free (open data)
Fetch-based wave exposure indices for the coast of temperate Australia.
Good for: Reef and coastal ecology in southern Australia.
Listed for reference. Geo Horizons is not affiliated with these organizations, and WEMo on the web is not affiliated with or endorsed by NOAA. Descriptions are drawn from each project's own pages as of October 2026. Know a tool that belongs here, or see something out of date? Email [email protected].