Out of the 1.4 million lakes in the world that are larger than 10 hectares, nearly 900,000 lakes are located in Canada, a new global database of lakes compiled by geographers at McGill University reveals.
The global database of lakes as published in Nature Communications is the world’s most complete database of lakes and has been created to help scientists around the world better understand the role played by lakes in Earth’s complex environmental systems including weather patterns, hydrological cycle, transport and distribution of nutrients, water pollution, among other things.
Previous studies have estimated surface area or shoreline length of the lakes, but one of the toughest problems to solve has been the amount of water that is stored in these lakes. To find this out, researchers made use of the latest improvements in satellite data and used computer models calculate the volume of water stored in more than 1.4 million lakes that are larger than 10 hectares, or roughly 14 soccer fields.
The researchers also reveal that the total amount of water stored in these 1.4 million lakes is more than 180,000 cubic kilometres and the total shoreline of these lakes stands at seven million kilometres and it is more than four times longer than the global ocean coastline. Further, if all the water in these lakes is spread over Earth’s landmass, it would form a layer some four feet (1.3 metres) deep.
“When you think of all the processes that take place at the interface of lakes and their landscapes, from providing habitat for aquatic or amphibian species to contributions to greenhouse-gas emissions, it underscores the importance of lakes in the Earth’s ecosystems,” notes Mathis Messager, the study’s first author.
Beyond the volume of water and the lake shoreline, researchers have also estimated how long water typically “resides” in each of the lakes – meaning the amount of time from the moment water enters a lake until it flows out. Scientists determine that on an average water resides in the lakes for about five years in all lakes. There are exception to this with around 3,000 lakes having residence times estimated at 100 years or more.
The McGill team is making its new database available for use by researchers around the world. The researchers are also working on new features that could be added, such as data on the surrounding watersheds that feed the lakes.