Allen Coral Atlas (ACA) - Geomorphic Zonation and Benthic Habitat - v2.0

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ocean sentinel2-derived


The Allen Coral Atlas dataset maps the geomorphic zonation and benthic habitat for the world's shallow coral reefs at 5 m pixel resolution. Also included is a global reef extent product that maps additional reef areas unable to be explicitly included in the geomorphic and benthic mapping. The underlying satellite image data are temporal composites of PlanetScope satellite imagery spanning 2018-2020. The habitat maps are created via a machine learning approach with contextual editing, using a range of imagery, bathymetry and derived products as input data, trained via a globally consistent reference data set. A full description of the methods and approaches can be found in the methods section of the Allen Coral Atlas website.

The first version (v1.0) of the Allen Coral Atlas was completed in Q4 2021, and this new version (v2.0) has a wide range of improvements across the globe that incorporated both user feedback on v1.0 and new technical developments in mapping methodology. A brief overview of the changes can be found here and a more comprehensive technical summary can be found here.

The Allen Coral Atlas was funded by Vulcan Inc. and is managed by the Arizona State University Center for Global Discovery and Conservation Science. Partners include Planet, the University of Queensland, and the Coral Reef Alliance.

Scientific background publications:

  • Lyons, M. B., Roelfsema, C. M., Kennedy, E. V., Kovacs, E. M., Borrego-Acevedo, R., Markey, K., ... & Murray, N. J. (2020). Mapping the world's coral reefs using a global multiscale earth observation framework. Remote Sensing in Ecology and Conservation, 6(4), 557-568. doi:10.1002/rse2.157

  • Kennedy, E. V., Roelfsema, C. M., Lyons, M. B., Kovacs, E. M., Borrego-Acevedo, R., Roe, M., ... & Tudman, P. (2021). Reef Cover, a coral reef classification for global habitat mapping from remote sensing. Scientific Data, 8(1), 1-20. doi:10.1038/s41597-021-00958-z

  • Roelfsema, C. M., Lyons, M., Murray, N., Kovacs, E. M., Kennedy, E., Markey, K., ... & Phinn, S. R. (2021). Workflow for the generation of expert-derived training and validation data: a view to global scale habitat mapping. Frontiers in Marine Science. doi:10.3389/fmars.2021.643381

  • Li, J., Knapp, D. E., Lyons, M., Roelfsema, C., Phinn, S., Schill, S. R., & Asner, G. P. (2021). Automated global shallow water bathymetry mapping using Google Earth Engine. Remote Sensing, 13(8), 1469. doi:10.3390/rs13081469

  • Li, J., Knapp, D. E., Fabina, N. S., Kennedy, E. V., Larsen, K., Lyons, M. B., ... & Asner, G. P. (2020). A global coral reef probability map generated using convolutional neural networks. Coral Reefs, 39(6), 1805-1815. doi:10.1007/s00338-020-02005-6

Allen Coral Atlas maps, bathymetry and map statistics are © 2023 Allen Coral Atlas Partnership and Vulcan, Inc.


5 meters


Name Description

Classification of geomorphic zonation.


Classification of dominant benthic composition.


Globally standardised reef extent product that integrates a number of global reef classification and bahtymetry products ("Reef Extent" on the Atlas portal).

geomorphic Class Table

Value Color Description
0 #000000 Unmapped
11 #77d0fc Shallow Lagoon - Shallow Lagoon is any closed to semi-enclosed, sheltered, flat-bottomed shallow sediment-dominated lagoon area.
12 #2ca2f9 Deep Lagoon - Deep Lagoon is any sheltered broad body of water semi-enclosed to enclosed by reef, with a variable depth (but shallower than surrounding ocean) and a soft bottom dominated by reef-derived sediment.
13 #c5a7cb Inner Reef Flat - Inner Reef Flat is a low energy, sediment-dominated, horizontal to gently sloping platform behind the Outer Reef Flat.
14 #92739d Outer Reef Flat - Adjacent to the seaward edge of the reef, Outer Reef Flat is a level (near horizontal), broad and shallow platform that displays strong wave-driven zonation
15 #614272 Reef Crest - Reef Crest is a zone marking the boundary between the reef flat and the reef slope, generally shallow and characterized by highest wave energy absorbance.
16 #fbdefb Terrestrial Reef Flat - Terrestrial Reef Flat is a broad, flat, shallow to semi-exposed area of fringing reef found directly attached to land at one side, and subject to freshwater run-off, nutrients and sediment.
21 #10bda6 Sheltered Reef Slope - Sheltered Reef Slope is any submerged, sloping area extending into Deep Water but protected from strong directional prevailing wind or current, either by land or by opposing reef structures.
22 #288471 Reef Slope - Reef Slope is a submerged, sloping area extending seaward from the Reef Crest (or Flat) towards the shelf break. Windward facing, or any direction if no dominant prevailing wind or current exists.
23 #cd6812 Plateau - Plateau is any deeper submerged, hard-bottomed, horizontal to gently sloping seaward facing reef feature.
24 #befbff Back Reef Slope - Back Reef Slope is a complex, interior, - often gently sloping - reef zone occurring behind the Reef Flat. Of variable depth (but deeper than Reef Flat and more sloped), it is sheltered, sediment-dominated and often punctuated by coral outcrops.
25 #ffba15 Patch Reef - Patch Reef is any small, detached to semi-detached lagoonal coral outcrop arising from sand-bottomed area.

benthic Class Table

Value Color Description
0 #000000 Unmapped
11 #ffffbe Sand - Sand is any soft-bottom area dominated by fine unconsolidated sediments.
12 #e0d05e Rubble - Rubble is any habitat featuring loose, rough fragments of broken reef material.
13 #b19c3a Rock - Rock is any exposed area of hard bare substrate.
14 #668438 Seagrass - Seagrass is any habitat where seagrass is the dominant biota.
15 #ff6161 Coral/Algae - Coral/Algae is any hard-bottom area supporting living coral and/or algae.
18 #9bcc4f Microalgal Mats - Microalgal Mats are any visible accumulations of microscopic algae in sandy sediments.

reef_mask Class Table

Value Color Description
0 #000000 Not reef
1 #ffffff Reef

Terms of Use

Terms of Use





Explore with Earth Engine

Code Editor (JavaScript)

var dataset = ee.Image('ACA/reef_habitat/v2_0');

// Teti'aroa, an atoll in French Polynesia.
Map.setCenter(-149.56194, -17.00872, 13);

// The visualizations are baked into the image properties.

// Example mask application.
var reefExtent ='reef_mask').selfMask();
Map.addLayer(reefExtent, {}, 'Global reef extent');

// Geomorphic zonation classification.
var geomorphicZonation ='geomorphic').selfMask();
Map.addLayer(geomorphicZonation, {}, 'Geomorphic zonation');

// Benthic habitat classification.
var benthicHabitat ='benthic').selfMask();
Map.addLayer(benthicHabitat, {}, 'Benthic habitat');
Open in Code Editor