Global extent and distribution of artificial, residential waterways in estuaries

Artificial residential waterways are now widespread in the world’s estuaries. We used the global mapping tool, Google Earth, to determine that there are nearly 4000 linear km of artificial waterways globally, covering an area of 270 km². Residential waterways constructed as open, flow-through canal estates are at their greatest extent in North America (77% of global linear extent), where systems are typically longer and narrower, with more openings and dead-ends than systems elsewhere. The remaining canal estates are spread across all other continents except Antarctica: Asia (7%), Europe (7%), Oceania (7%), South America (0.9%), and Africa (0.6%). A relatively recent design change from open canals to artificial estuarine lakes with tidal barriers has occurred on all continents except Africa, most extensively in Australia (14 km² area, 57 independent systems). The extremely large expansion in artificial residential waterways aimed at increasing opportunities for waterfront living by humans has also modified and expanded estuarine habitat available to aquatic biota. Research can best underpin planning and management of these types of waterways by focussing on their value as habitat and their provision of other goods and services.