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| Earth Resources Observation and Science (EROS) |
Jeffrey J. Danielson, UNEP GRID/EROS Data Center
e-mail: daniels@grid2.cr.usgs.gov
daniels@grid2.cr.usgs.gov
Work your way through the poster using the imagemap, or use the links below.
Introduction | Statement of Research | GIS and Hydrologic Modeling | Digital Elevation Models (DEMs) (149K image) | Flow Directions (116K image) | Basin Delineation (149K image) | Validation of African Drainage Basins (50K image) | Sub-Watershed Extractions (99K image) | Conclusion | Bibliography | Author Information | Abstract
At the U.S. Geological Survey's EROS Data Center, the USGS, the National Aeronautics and Space Administration, the United Nations Environment Program, and others are developing approximately 30 arc second resolution digital elevation models (DEMs). These DEMs are important because they provide the basic data as well as derivative information such as slope, aspect and flow characteristics that are critical in environmental problems for hydrologic, biologic, and geologic studies.
DEM's have been available for many years but only recently have computer speeds, GIS algorithms and appropriate models become available to process DEMs in hydrologic applications (Moore, 1991). Digital delineation of drainage basins from DEM's is a primary example of this newly-evolving capability. Drainage basins are crucial for resource management, ecosystems analysis, and global-change studies. This poster describes drainage basin delineation from a one kilometer DEM on a continental scale for Africa, as part of the on-going project on drainage database design based on DEMs at the EROS Data Center.
A GIS is a tool for collecting, storing, retrieving, transforming, and displaying spatial data (Burrough, 1986). Hydrologic modeling is concerned with the flow of water and its constituents over the land surface and subsurface environment (Maidment, 1993). One important concept in hydrologic modeling is the river basin. The modeling of drainage basins is accomplished most easily with the digital elevation model (Maidment, 1993).
1 KM resolution DEMs will be valuable to those who want to extract drainage features for applications on a global scale. An established methodology for basin delineation and verification will benefit users in many disciplines. Specific watershed thresholding will be useful in management situations that employ drainage areas for spatial control. The improved uses of DEMs will be a major resource in examination of global problems in the future.
Burrough, P.A. 1986. Principles of Geographical Information Systems for Land Resource Assessment. Oxford: Clarendon Press.
Czaya, E. 1981. Rivers of the World. New York: Van Nostrand Reinhold.
Food and Agriculture Organization (FAO). 1995. UNEP/FAO World and Africa Data Base. Rome: FAO.
Jenson, S.K. and J.O. Domingue. 1988. Extracting Topographic Structure from Digital Elevation Data for Geographic Information Systems Analysis. Photogrammetric Engineering and Remote Sensing 54(11): 1593-1600.
Environmental Systems Research Institute (ESRI). 1992. Cell Based Modeling with GRID. Redlands, CA: ESRI.
Maidment, David R. 1993. GIS and Hydrologic Modeling. Environmental Modeling with GIS, ed. Michael F. Goodchild, Bradley O. Park, and Louis T. Steyaert. New York: Oxford University Press.
Moore, I.D. 1991. Digital Terrain Modeling: A Review of Hydrological, Geomorphological, Biological Applications. Hydrological Processes 5(1): 3-30.
Sharpe, Jennifer B. 1994. Delineating Drainage Basins Using A DEM. Unpublished Paper.
Verdin, Kristine L. and Susan K. Jenson. 1996. Development of Continental Scale Digital Elevation Models and Extraction of Hydrographic Features. Third International Conference/Workshop on Integrating Geographic Information Systems and Environmental Modeling. National Center for Geographic Information and Analysis. Santa Fe, NM.
Jeffrey J. Danielson
Hughes STX
EROS Data Center
Sioux Falls, SD 57198
(605) 594 - 6148
email: daniels@grid2.cr.usgs.gov
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