METADATA FILE I. General description of data set ----------------------------------- Name Sub-watershed Drainage Basins for Baltic Sea drainage basin region Geographic Level Regional Specific Area Baltic Sea drainage basin region Lat/Long Region Boundaries NW-X: 0-E , SW-X: 0-E NW-Y: 75-N , SW-Y: 45-N SE-X: 40-E , NE-X: 40-E SE-Y: 45-N , NE-Y: 75-N Infoterra Keyword(s) Watershed management (12670) Natural drainage systems (13140) Catchment areas (13210) Run-off and seepage (13326) Inorganic pollutants (22134) Land pollution (12124) Human population (14213) Other Keyword(s) Nutrient loading, land cover, population Primary Data Acquisition Period Start Date: 1986 End Date: 1986 Supplier GRID-Arendal. PO Box 1602, Myrene. N-4801 Arendal, Norway. Contributor GRID-Arendal. PO Box 1602, Myrene. N-4801 Arendal, Norway. Publication Reference Langaas, S. 1993. Some Georeferenced Data Sets for use within Sub-project 1; Land Use and Ecological Carrying Capacity, of the Baltic Drainage Basin Project. Technical Note. GRID-Arendal. 10 pages + apps. Sweitzer, J., Langaas, S., and Folke, C. 1996. Land Cover and Population Density in the Baltic Sea Drainage Basin: A GIS database. AMBIO 25(3):191-198. Stalnacke, P. 1994. Documentation of data sources and data quality in the calculation of the land based loads of eutrophying substances to the Baltic Sea, 1970 - 1990. Note, Dept. of Water and Environmental Studies, Linkoping University. 15 pages (in Swedish/English). HELCOM. 1986. Water balance of the Baltic Sea. Baltic Sea Environment Proceedings No. 16., The Helsinki Commission, Finland. 174 pages. Documentation (overview) The main Baltic Sea drainage basin map was created by M. Falkenmark and Z. Mikulski (HELCOM 1986). Both map projection and scale are unknown. Independent measurements indicate a scale of approximately 1:5,000,000. Two additional maps were used to provide more accurate delineations in the Danish Straits and Kattegat sub- regions. These paper maps were also of unknown scale and projection. The Digital Chart of the World (DCW) by ESRI was used for spatial positioning when joining all data sets. These map sources identified 81 sub-basins, which can be aggregated to seven major watersheds for the following major water bodies that define the Baltic Sea: Bothnian Bay, Bothnian Sea, Gulf of Finland, Gulf of Riga, the Baltic Proper, Danish Straits, and the Kattegat. The main Baltic Sea drainage basin map was digitised and transformed in three separate sections using PC ARC/INFO. The Root Mean Square (RMS) error ranged between 0.01 and 0.02. Four sub- basins from the Danish Straits and nine from the Kattegat paper maps were digitised. The RMS errors were 0.01 and 0.06, respectively. All sections were joined together using the APPEND command. Although some RMS errors were high, the final drainage basin data set lines up well with other coverages in the database. The coverage was edited for dangling arcs and label errors. When the editing process was complete, topology was created using the CLEAN command with a 20 meter fuzzy tolerance and dangle length. All polygons were assigned unique id's before attribute data was added. An item called SUBID was added to the coverages .PAT file. This value represents the sub-basin or water body for which each polygon belongs. SUBID served as a bridge item to join additional attributes that existed in an EXCEL spreadsheet. Individual SUBIDs were assigned by selecting polygon label points in ARCEDIT and CALCing SUBID to be the correct value. Extensive error checking was performed before all other attribute data was appended. In addition to the added item SUBID, 21 other attributes were appended to the cover .PAT file. These attributes originated from (a) and database of monthly loads of land based eutrophying substances (Stalnache, 1994), (b) data extracted from the Land Cover data set, and (c) data extracted from the Population Distribution data set. The final BASINS coverage has a total of 26 attributes, including the four automatically generated by ARC/INFO. Because an IDRISI image file can only display one data attribute at a time, a comma delimited ASCII file was generated so IDRISI users could generate an image based on any of the ARC/INFO polygon coverage attributes. IDRISI users can accomplish this by generating value files from the comma delimited ASCII file. There are a total of 26 attributes in the file called BASINS.CSV. ***** Attention IDRISI users ***** The final IDRISI image has a 500 meter resolution. We also decided to include the IDRISI line file created from the ARC/INFO polygon coverage, called BASINVEC. This file can easily be converted into an image of any desired resolution using the INITIAL command to generate a template image and the POLYRAS command to update the template image with the IDRISI area line file information. Note: the line file appears to be corrupted around the Danish Straits and Kattegat sub-regions when viewed on screen. But the file works well when generating an output image. ************************************************************************ Contact information Hugo Ahlenius phone: +47-370-35650 UNEP/GRID-Arendal fax: +47-370-35050 e-mail: mapmaster@grida.no II. Detailed description of data set (members) ----------------------------------------------- Data set type IDRISI 4.1 line file (extracted areas) Description BASINVEC - Sub-watershed Drainage Basins File Type/Size Integer/binary: 550 KB Access Free access, unrestricted Copies (available sites) CD-ROM - being distributed by GRID-Arendal World Wide Web (WWW), GRID-Arendal URL - http://www.grida.no III. Technical information about vector data --------------------------------------------- Source Data set ARC/INFO polygon Basins coverage Values from SUBID ARC/INFO attribute Scale Approximately 1:5,000,000 Feature Type Line (with extracted areas) Projection Name Lambert Azimuthal Equal Area Projection Parameters Units: meters Spheroid: International 1909 Radius: 6,378,388 Longitude of centre of projection: 20.00.00 Latitude of centre of projection: 60.00.00 False Easting: 0 False Northing: 0 Projection boundaries Xmin: -1,000,000 Ymin: -1,300,000 Xmax: 1,000,000 Ymax: 1,300,000