National Geographic puts McGill hydrographer on the map


National Geographic puts McGill hydrographer on the map Bernhard Lehner's one-of-a-kind global rivers map to be included in April issue of magazine

Bernhard Lehner, Dept. of Geography at McGill University, is a hydrographer whose work has literally just gone global. Fusing the fields of hydrology and cartography, a one-of-a-kind map of the world's rivers he created will be included as a pull-out in the April 2010 "Fresh Water" Issue of National Geographic - the iconic magazine that's read in 32 languages by more than 8 million people every month.

"I really like that this scientific product will get such broad attention," said Lehner. "It confirms that geography contributes to issues that the public is interested in. ... That it's important beyond academia." He added:  "National Geographic usually produces very colourful maps. This one's nearly monochromatic. ... A little bit of text, no photos, no images. Their designers insisted that the rivers alone be the focus. We've never had a proper look at the rivers globally in good quality before. And now we have."

Six years ago, while working with the World Wildlife Fund (WWF), Lehner embarked on a wildly ambitious project: to be the first to build a comprehensive, seamless, digital map of the world's rivers, in unprecedented resolution and detail.

Using data gathered in 2000 by NASA's Shuttle Radar Topography Mission (SRTM) - a space shuttle flight dedicated to measuring the topography of the Earth's surface - as his starting point, Lehner produced a high-resolution map of a small portion of the Amazon Basin. Maps of the Amazon and South America eventually followed. The project that WWF dubbed "HydroSHEDS" (Hydrological data and maps based on SHuttle Elevation Derivatives at multiple Scales) kept growing from there, computing power was ramped-up and Lehner and his team began writing code used to eventually run through all the continents.

Lehner left WWF for a professorship in Global Hydrology in the Geography Department at McGill four years ago and has since been working steadily on the map, with continued support from WWF.

While it is not the first global river map in existence - one may be found in any atlas - it is the first high-resolution, seamless, global river map that is also available in a digital, pixel-based format. "It's produced using a GIS software package that's pixel-based - something that hydrological [computer] models need," explains Lehner.

Another element unique to this map is that it can be coupled with other maps or hydrological models. This enables Lehner to provide information on attributes like river flow and to distinguish large from small rivers; a feature that traditional maps have not been able to illustrate easily in the past.

While the global river map is being formally released in a paper format in National Geographic, HydroSHEDS remains a work-in-progress as Lehner and his team continue to add more attributes like river names and classes, the outlines of sub-basins and catchment areas and links to other layers such as lakes and reservoirs.

The map already appears to have limitless practical applications. From conservation biology to climate modelling to irrigation and food production, the map is in high-demand by specialists from various fields. The map data are free and available for download, and Lehner estimates that since the data sets were made available online, there have been about a thousand downloads a month.

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