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Drainage Network and Inland Water Bodies of Nigeria

Attributes of the shapefile includes

Drainage line type - Code Definition

1. = Stream, river, channelized river

2. = Inland water body shoreline

3. = Wet sand limit

4. = Canal, aqueduct, flume, penstock, kanat, or similar feature (clearly

identified by ONC map annotation)

5. = Glacial limit

6. = Snowfield, glacier, or land ice water ice or ocean limit

7. = Ice free limit (land/ice line)

8. = Connector (used to separate inland water from open ocean or ocean

ice)*

9. = Tile boundary or null arc

*These lines were derived from the border between the shade for inland water

(dark blue) and open ocean or ocean ice (light blue) on the ONC sheets. The

cartographic judgements applied to the use of open ocean versus inland water

shading in near shore situations varies from sheet to sheet,

Drainage line status - Code Definition:

1. = Perennial (used for rivers and streams only)

2. = Nonperennial (used for rivers and streams only)

3. = Definite (used for inland shorelines only)

4. = Indefinite (used for inland shorelines only)

5. = Unsurveyed perennial

6. = Unsurveyed nonperennial

7. = Abandoned

8. = Under construction

9. = Suspended or elevated

10. = Underground

11. = Above ground

88. = Tile boundary

99. = None (no status attribute associated with feature)

Drainage feature type - Code Definition:

1. = Perennial inland water. Includes perennial lakes and streams,

estuaries, lagoons, unsurveyed perennial streams, reservoirs, and

navigable canals

2. = Nonperennial inland water. Includes nonperennial and seasonally

fluctuating lakes and streams, wadis, sabkhas, and abandoned navigable

canals

3. = Wet sand. Includes wet sand and sand deposits in and along riverbeds

4. = Snowfields, glacier, ice fields, or ice caps

9. = None. This code is used for any area that is not water, wet sand,

snowfield, glacier, ice field or ice cap. Polygons with this code would

include the background polygon, islands within inland water or ice

areas, land areas enclosed by stream or river courses, or ocean areas.

Data origin:

http://data.geocomm.com/catalog/index.html

Positional accuracy of the drainage network was checked against google maps and a digital elevation model. Particularly in the upper streams positional accuracy is low, respectively does not fit to the contour lines in any case.