MERIT Hydro: A High-Resolution Global Hydrography GIS Dataset

Caitlin Dempsey


Scientists have developed MERIT Hydro, a new global map of river systems, with a resolution of 3‐arc sec (90 meters at the equator).  

The high-resolution dataset was created with crowdsourced hydrography data from OpenStreetMap as well as water body data (G1WBM, Global Surface Water Occurrence).  This data, coupled with MERIT DEM, was fed into an algorithm that extracted river networks by separating actual inland basins from false depressions caused by errors in the topographic data collected by spacecraft radar systems such as NASA’s Shuttle Radar Topography Mission.

MERIT hydro data mapped for different regions of the world. Maps: Dai Yamazaki
MERIT hydro data mapped for different major rivers of the world. Maps: Dai Yamazaki

The researchers pulled OpenStreetMap data tagged with water related subjects such as “waterway,” “river,” “stream,” “brook,” and “wadi.”  This allowed the algorithm to identify small streams not detectable on Landsat imagery.  It also enabled the researchers to flag man-made hydrological structures such as canals that might be prone to flooding.

Downloading MERIT Hydro

The hydrological dataset, in geoTIFF format, has been made freely available for research and education purposes and can be downloaded from http://hydro.iis.u‐

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The Study

Yamazaki, D., Ikeshima, D., Sosa, J., Bates, P. D., Allen, G., & Pavelsky, T. (2019). MERIT Hydro: A high‐resolution global hydrography map based on latest topography datasets. Water Resources Research

A More Accurate Global River Map, Eos, July 12, 2019


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About the author
Caitlin Dempsey
Caitlin Dempsey is the editor of Geography Realm and holds a master's degree in Geography from UCLA as well as a Master of Library and Information Science (MLIS) from SJSU.