Global multi-scale segmentation of continental and coastal waters from the watersheds to the continental margins
- 1Biogeochemical Modelling of the Earth System, Dept. of Earth & Environmental Sciences, CP 160/02, Université Libre de Bruxelles, 1050 Brussels, Belgium
- 2Department of Earth Sciences – Geochemistry, Faculty of Geosciences, Utrecht University, Utrecht, the Netherlands
- 3Institute for Biogeochemistry and Marine Chemistry, KlimaCampus, Universität Hamburg, Bundesstrasse 55, 20146 Hamburg, Germany
- 4Ecohydrology Reserach Group, Dept. Earth and Environmental Sciences, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
Abstract. Past characterizations of the land–ocean continuum were constructed either from a continental perspective through an analysis of watershed river basin properties (COSCATs: COastal Segmentation and related CATchments) or from an oceanic perspective, through a regionalization of the proximal and distal continental margins (LMEs: large marine ecosystems). Here, we present a global-scale coastal segmentation, composed of three consistent levels, that includes the whole aquatic continuum with its riverine, estuarine and shelf sea components. Our work delineates comprehensive ensembles by harmonizing previous segmentations and typologies in order to retain the most important physical characteristics of both the land and shelf areas. The proposed multi-scale segmentation results in a distribution of global exorheic watersheds, estuaries and continental shelf seas among 45 major zones (MARCATS: MARgins and CATchments Segmentation) and 149 sub-units (COSCATs). Geographic and hydrologic parameters such as the surface area, volume and freshwater residence time are calculated for each coastal unit as well as different hypsometric profiles. Our analysis provides detailed insights into the distributions of coastal and continental shelf areas and how they connect with incoming riverine fluxes. The segmentation is also used to re-evaluate the global estuarine CO2 flux at the air–water interface combining global and regional average emission rates derived from local studies.