One of the major constraints in conducting scientifically sound global environmental assessments is the lack of high quality, accurate and consistent spatial data sets over large areas. UNEP, through its network of Global Resource Information Database (GRID) centres, has been active in assembling such databases for environmental assessments for over a decade.
This new globally consistent 1 km. resolution (1:1 million map scale) digital topographic database is called GTOPO 30 (Global Topography at 30 arc/second). It is the product of a three-year international collaborative effort involving UNEP, the US Geological Survey (USGS), the US National Aeronautics and Space Administration (NASA), Japan's Geographical Survey Institute (GSI) and Mexico's National Institute for Statistics, Geography and Information (INEGI). Additional data were also provided by New Zealand's Manaaki Whenua Landcare Research Ltd. and the Antarctic Digital Database.
What is unique about this effort is that data from different sources and resolutions have been brought together and a consistent product has been generated using new algorithms and software developed by scientists of the Earth Resources Observation Systems (EROS) Data Center in Sioux Falls, South Dakota, which also hosts the UNEP/GRID North American node.
Topographic data in digital form is among the core data sets needed for environmental assessments. The most fundamental type of topographic information is elevation data, which is used to yield derived attributes such as slope, aspect, relief drainage and insolation. Digital Elevation Models (DEMs) provide a digital representation of a portion of the earth's topography over a two-dimensional surface.
DEMs are used in many applications in the earth and environmental sciences such as drainage basin boundary delineation, hydrological runoff modelling, and landform simulation and classification. The amount and rate of flow in surface and sub-surface water systems, for instance, can be modelled using elevation data towards improving the information base for water assessments. Combined with other data, such as soil, land cover and climate variables, the data can be used for a range of applications, for example, predicting soil erosion, and flood impacts and for integrated water resources planning and management.
Notwithstanding the enormous size of the database, consisting of 933 million pixels, over 8,000 users around the world have already downloaded data from the Internet site. In the words of the Regional Coordinator of UNEP's Environmental Assessment Programme in North America, Dr. Ashbindu Singh "unprecedented demand for the data have exceeded our all expectations. Obviously, serious users are discovering that such critical data sets are needed to provide a sound scientific basis for sustainable development decision making."
UNEP Information Note. For information only. Not an official document.
FIRST GLOBALLY CONSISTENT DIGITAL TOPOGRAPHIC DATABASE COMPLETED FOR ENTIRE EARTH SURFACE
Collaborative effort results in success
For further information, please contact:
Dr. Ashibindu Singh
UNEP Environmental Information and
Assessment Programme-North America
USGS-EROS Data Center
Sioux Falls, SD 57198 USA