Dr. Bernhard Lehner
Associate Professor of Global Hydrology
Department of Geography
& Earth System Science Program
Main Research Interests
As a faculty member of the Department of Geography and the new Earth System Science program, my main research theme is large-scale hydrology. I study the terrestrial water cycle of large river basins, continents, or the entire globe and investigate the effects of climate and global change on regional water resources and hydrologic regimes, including floods and droughts. Hydrological models, global data sets, and GIS and remote sensing tools are typical components of my research projects.
Hydrology and GIS
As part of my research, I am contributing to the improvement and generation of high-quality data layers to eliminate some of the most common restrictions for global hydrological modeling. Key projects include the design and development of global river network maps, drainage direction schemes and watershed delineations (HydroSHEDS, DDM30) as well as global lakes, wetlands and reservoir databases (GLWD, GRanD) – see project descriptions below. The goal of these GIS projects is to generate basic data layers in support of regional and global hydrological modeling, watershed analyses, and freshwater conservation planning at a quality, resolution and extent that have previously been unachievable.
Between 2002 and 2006 I have been a member of the Conservation Science Program of the World Wildlife Fund (WWF) in Washington DC, and I am now an advising Science Fellow for them. My research projects focused on blending rigorous hydrology with practical applications in biodiversity conservation. I conducted analyses that spanned multiple scales (from local to global) and covered a broad variety of topics, including general hydrological modeling, regional water resources assessments, and studies on the possible effects of climate change, land cover change, and dam construction. Based on these experiences, I am interested in large-scale environmental flow assessments and integrated freshwater conservation.
Current and past projects that I led or was involved in
HydroSHEDS – Hydrological data and maps based on Shuttle Elevation Derivatives at multiple Scales
HydroSHEDS is a new hydrographic mapping product that provides river and watershed information for regional and global-scale applications in a consistent format. It offers a suite of geo-referenced data sets (vector and raster) at various scales, including river networks, watershed boundaries, drainage directions, and flow accumulations. HydroSHEDS is based on high-resolution elevation data obtained during a Space Shuttle flight for NASA’s Shuttle Radar Topography Mission (SRTM).
HydroSHEDS Overview (WWF)
HydroSHEDS Data (USGS)
HydroSHEDS Map (National Geographic)
HydroSHEDS Story 1 (McGill Reporter)
HydroSHEDS Story 2 (NASA Earth Observatory)
HydroSHEDS Story 3 (Earth&Sky)
HydroSHEDS Story 4 (Amazon)
GLWD – Global Lakes and Wetlands Database
Drawing upon a variety of existing maps and inventories, a new Global Lakes and Wetlands Database (GLWD) has been created. The combination of best available sources for lakes and wetlands on a global scale (1:1 to 1:3 million resolution), and the application of GIS functionality enabled the generation of a database which focuses in three coordinated levels on (1) large lakes and reservoirs, (2) smaller water bodies, and (3) wetlands.
GLWD Overview and Data (WWF)
GRanD – Global Reservoir and Dam Database
Coordinated by the Global Water System Project (GWSP) and based on a variety of existing data sets, maps and registers, a group of international researchers is currently compiling information on global reservoirs and dams. The final database will include georeferenced locations and attribute data for about the largest 6000 reservoirs worldwide. Data is scheduled for completion within 2008.
EuroWasser – Estimating the effect of global change on European water resources and hydrology: enhancement and application of a global water model
The EuroWasser project (my PhD project at the University of Kassel, Germany) focused on the improvement of an existing global hydrological model and its application in Europe to assess the effects of climate and socio-economic change on water availability, water stress, hydropower generation, and the frequencies of floods and droughts. The applied WaterGAP model (Alcamo et al. 2003; Döll et al. 2003) is an integrated global water model, i.e. it combines both a physically based hydrological model with a socio-economically driven water use model, including industrial, household and agricultural water use scenarios.
DDM30 – Global Drainage Direction Map at 30 minute resolution
The global drainage direction map DDM30 is a raster map that describes the drainage directions of surface water with a spatial resolution of 30’ longitude by 30’ latitude. 66896 individual grid cells, covering the entire land surface of the globe (except Antarctica), are connected to each other by their respective drainage direction and are thus organized into drainage basins.
DDM30 Overview and Data (University of Frankfurt)