METADATA FILE

I.  General description of data set
-----------------------------------

Name
	Wetlands 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)
	Wetlands ecosystems (12600)
	Waterlogged lands (12660)
	Estuarine ecosystems (14278)

Other Keyword(s)
	Swamps, marshes, fens, bogs, emergent / submergent / hydrophilic
	vegetation, hydrosols  

Primary Data Acquisition Period
	Start Date: 1974
	End Date: 1993

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 Use and 
		Population Density in the Baltic Sea Drainage Basin: A GIS 
		database. AMBIO 25(3): 191-198.

Documentation (overview)
		Wetland distribution for the Baltic Sea region was derived
	from the association of regional wetland area statistics with wetland
	locations represented in the DCW Land Cover layer.  This layer 
	depicts "undifferentiated wetlands" that includes swamps, marshes, 
	bogs, hummocks, ridges, and peat bogs but has a quality which does
	not allow it to be used alone (ESRI, 1992).  Statistics on wetland 
	area for administrative regions within the drainage basin were 
	collected from various sources (see Technical Report).  Vector 
	coverages were converted into IDRISI image files with a 1 km 
	resolution.
		The method used to combine wetlands area statistics with the
	DCW wetlands data set involved spatial allocation of the statistical
	values of wetland area with equal probability throughout the DCW 
	wetland cells.  Wetland raster cells were extracted per 
	administrative unit.  The area of DCW wetlands was divided by the
	statistical value of wetland area for the same administrative unit.
		The fractional value assigned to the DCW wetland raster cells 
	no longer represented one square kilometer of wetland, but rather, a 
	value depending upon the wetland area from the DCW and administrative
	regional statistics. The fractional wetlands data set was aggregated 
	into a 50 km square cell size.  The final wetlands data layer 
	represents wetland distribution as average wetland area per 50 square 
	kilometers throughout the Baltic Sea region.  It should be noted that
	the quality of this data is lower than the others layers in the
	Baltic Sea drainage basin database.  This is partly reflected in the 
	coarse resolution of the final data set.
		An added item called PERCENT is found in the Wetlands data
	set.  This integer value represents percent wetland area within a 
	given unit (i.e., vector polygon or raster cell).  Note:  All 'no
	data' units are coded percent = 150.  This was done to distinguish
	between 0 percent and 'no data' units.
		The final wetlands IDRISI image was converted back into an
	ARC/INFO polygon coverage, using PC ARC/INFO.  Wetlands data can
	be obtained in both ARC/INFO and IDRISI formats.
		
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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
	ARC/INFO vector

Description
	WETLANDS - Wetlands for Baltic Sea region

File Size
	ARC/INFO export file:  271 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
	Digital Chart of the World - LPCY data layer

Scale/Resolution
	Smallest unit is a 50 km x 50 km square polygon

Feature Type
	Polygon

Number of Polygons
	355

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

Attributes                     Brief description

	Area,13,13,n,6          Area of polygon
	Perimeter,13,13,n,6     Perimeter of polygon
	Wetlands_,11,11,n,0     Internal coverage record value
	Wetlands_id,11,11,n,0   Internal coverage polygon ID
	Percent,5,5,n,0         Percent area of wetlands within polygon