Authors / CoAuthors
Unknown
Abstract
The Valley Networks dataset covers the whole of Christmas Island. It contains low elevation lines that were constructed from the 25K Digital elevation map. The lines were obtained by running a series of ArcView grid commands using the Hydrologic Modeling v1.1 extention. The valley_net.shp contains the following fields: Field Type Precision Decimal---------------------------------------------------Shape FIELD_SHAPELINE 0 9Id FIELD_DECIMAL 0 11Gridcode FIELD_DECIMAL 0 10Length FIELD_DECIMAL 3 16
Product Type
dataset
eCat Id
81831
Contact for the resource
Custodian
Point of contact
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
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- GIS Dataset
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- AU-ACT
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
Publication Date
2003-01-01T00:00:00
Creation Date
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Purpose
Maintenance Information
asNeeded
Topic Category
geoscientificInformation
Series Information
Lineage
The 1987 DEM (NOTE: this year is possibly incorrect as all other sources state the valley network was created from a TIN DEM created from the 1:25000 data in 1999/2000) was used with the hydrologic modelling v1.1 (stored on CD1) extention was used to derive the valleys_net shape file. The following ArcView spatial operations were performed upon the ascii grid to create that shapefile: The Spatial Analyses/Map Calculator was used to assign null values to attributes in the DEM that had the values of 0. The following command was used upon that grid: ([Dem25k].isnull).con(0.asgrid,[Dem25k]) to give an output grid suitable for the hydrological grid functions Sinks [command] were filled using the grid derived from the DEM Flow direction [command] was calculated by using the grid created by filling the sinks Flow accumulation [command] was calculated from the flow direction grid Watersheds were created by: Selecting Flow accumulation and then selecting Flow accumulation from the menu. The minimum number of cells for the watershed = 9000 Flow accumulation was used to calculate stream networks grid The Stream networks grid was then converted to a shapefile in ArcView For simplicity, the stream networks were then edited to show only 5th order streams and above. In September 2003 this dataset was converted to the MGA(GDA94) projection using an x y shift (550015 = x, 8780001 = y) on the CIG85 projection.
Parent Information
Extents
[-10.5667, -10.4167, 105.5333, 105.7167]
Reference System
Spatial Resolution
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