Rice County Geologic Atlas, Part B

GWSL2PY metadata

Data Set Name: GWSL2PY

Metadata Entered By: Randy McGregor

Date: 6/9/98

First, a  proto sensitivity coverage was created by a stepwise UNION of ten different coverages in ARC/INFO. An order of priority was determined by Moira Campion based on which coverages would be drawn one on top of the other to visually depict water-table pollution sensitivity. Because the UNION command in ARC/INFO merges attributes in the order they are added, with matching items dropped from the incoming coverage, each incoming coverage was given a unique item(s) that would identify its components even after all ten had been unioned together.

CODE1 = 'y'

Polygons from the MGS depth-to-bedrock coverage where depth-to-bedrock is less than 50 ft. These polygons were selected using the selection criterion, 'CINTER' = '<50'. These polygons are rated 'CODE1' = 'y'. Any polygons internal to polygons with 'CODE1' = 'y' were coded as 'CODE1_INT' = 'y'. Thus, polygons with 'CODE1_INT' = 'y' represent areas where depth-to-bedrock is greater than 50 feet.

CODE2 = 'y'

Represents an interior 1/3 mile buffer along the edge of the Decorah-Platteville-Glenwood confining unit. There were no internal polygons

for areas with 'CODE2' = 'y'.

CODE3 = 'y'

Polygons from MGS' depth-to-bedrock coverage with depth-to-bedrock values greater than 50. This set of polygons is the compliment of 'CODE1' polygons. Thus, the entire county was subdivided into regions with depth-to-bedrock less than 50 feet and areas where depth-to- bedrock is greater than 50 feet. 'CODE3_INT', represent areas where depth to bedrock is less than 50 feet.

CODE4 = 'y'

Polygons from MGS' surficial geology coverage meeting one of the following criteria:

• 'MGSCODE' = 443002, 443006, 443102, 443521, 443527, 443528 (alluvium or outwash designations)

• 'MGSCODE'= 443001 (organic deposits) and within or near alluvial/outwash deposits.

These polygons were rated 'CODE4' = 'y,'and the internal polygons were designated 'CODE4_INT' = 'y'.

CODE5 = 'y'

Derived from a small coverage used only to counteract discrepancies between various data sources while keeping all sources unchanged. Polygons with 'CODE5' = 'y' have no scientific value and serve only a small cartographic purpose.

CODE6 = 'y'

Polygons from MGS' surficial geology coverage where 'MGSCODE' = 443001 (organic deposits) and not within or near alluvial/outwash deposits. Any internal polygons from this set were given 'CODE6_INT' = 'y'.

CODE7 = 'y'

Selected NWI Wetlands. Only wetlands of type 3 (shallow marsh), 4 (deep marsh) and 5 (lakes) were used. West of the Cannon River, wetlands over 3000 square meters are included; East of the river, wetlands over 1500 square meters are included. Internal polygons (islands within wetland areas) were designated 'CODE7_INT' = 'y'.

CODE8 = 'y'

Derived from a single polygon selected from the MGS' surficial geology coverage having 'MGSCODE' = 443505. This single polygon represents an area of glacial lake sediments. Any polygon having 'CODE8' = 'y' was derived from this single polygon.

CODE9 = 'y'

A 50 meter buffer zone around all but the smallest lakes from the USGS Digital Line Graph (DLG) hydrology layer. The size of the lakes that were excluded from the buffer operation was not documented.

CODE10 = 'y'

Derived from buffered areas around the arcs from the MGS' surficial geology line coverage where 'MGSCODE' = 449011 (eskers) and a portion of one arc with 'MGSCODE' = 449007 (fluvial channel bank, obscure). These arcs were buffered with a 50 meter tolerance and round end-points. In coverage units, this buffering distance roughly approximates the areal extent of these eskers, and was performed to 'polygonize' the line features.

Sensitivity ratings were calculated as follows:
 

Finally, this proto sensitivity coverage was dissolved on the item 'Sensitivity' resulting in 'gwsl2py.'