Difference between revisions of "Carneros Watershed: Map of Soil Erodibility Index"
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* Original source of data: SSURGO | * Original source of data: SSURGO | ||
| − | * Data analysis: [[Fred Watson | + | * Data analysis: Kathy Pugh and [[Fred Watson]] |
* Map produced by: Kathy Pugh | * Map produced by: Kathy Pugh | ||
* Map produced using: [[ArcMap]] | * Map produced using: [[ArcMap]] | ||
| Line 15: | Line 15: | ||
== Data Analysis Steps Taken == | == Data Analysis Steps Taken == | ||
| − | # | + | # Download SSURGO data |
| − | # | + | # Receive zip file of zip files, each one like soil_ca069.zip. |
| − | # | + | # Extract, and open basic shapefile of map-units (MU): soilmu_a_ca069.shp in Arc |
| − | # | + | # Can't read tables in this zip, because need special MS Access Template |
| − | # | + | # Download Access template from http://soildatamart.nrcs.usda.gov/templates.aspx |
| − | # | + | # Open template in Access; Enable Macros; and it should prompt for location of your tables |
| − | # | + | # Wait a few minutes while Access imports your tables |
| − | # | + | # Create some custom queries in Access to extract some kind of Kf for each map unit |
| − | ## | + | ## Review the SSURGO data model: http://soildatamart.nrcs.usda.gov/documents/SSURGO_2_2_DataModel_Part_1.pdf |
| − | ## | + | ## Each MapUnit contains several Components, each containing several Horizons. |
| − | ## | + | ## First query selects the surface horizons: |
| − | ## | + | ## - it joins tables muaggatt+component+chorizon, |
| − | ## | + | ## - joining on keys mukey and cokey |
| − | ## | + | ## - selecting only horizons whose hzdept_r is 0 (i.e. surface horizons) |
| − | ## | + | ## - includes the kffact (Kf-factor) and comppct_r (Percentage of map-unit occupied by Component) fields that will be used below |
| − | ## | + | ## Second query takes first as input, and is a MakeTable query, making the table that will be used in Arc |
| − | ## | + | ## - computes an expression 'yournamekf: Sum([comppct_r]*[kffact]/100)' |
| − | ## | + | ## - it is a Summation query, and the Summation is done on the yournamekf field (above) |
| − | ## | + | ## - the other two fields are musym and mukey, and they are GroupBy fields |
| − | ## | + | ## Run the second query; it will make a table |
| − | ## | + | ## Export the table to DBF format (one way of getting it to Arc) |
| − | # | + | # Back in Arc, add the DBF table as a layer |
| − | # | + | # Join the soilmu_a_ca069.shp layer to the DBF layer, using the mukey |
| − | # | + | # Change the soilmu_a_ca069.shp symbology to display quantitative based on the yournamekf field |
== Alternate versions == | == Alternate versions == | ||
Latest revision as of 07:44, 28 February 2011
Metadata
- Original source of data: SSURGO
- Data analysis: Kathy Pugh and Fred Watson
- Map produced by: Kathy Pugh
- Map produced using: ArcMap
- Coordinate system: Geographic Coordinate System - GCS_North_American_1983
- Datum: D_North_American_1983
Data Analysis Steps Taken
- Download SSURGO data
- Receive zip file of zip files, each one like soil_ca069.zip.
- Extract, and open basic shapefile of map-units (MU): soilmu_a_ca069.shp in Arc
- Can't read tables in this zip, because need special MS Access Template
- Download Access template from http://soildatamart.nrcs.usda.gov/templates.aspx
- Open template in Access; Enable Macros; and it should prompt for location of your tables
- Wait a few minutes while Access imports your tables
- Create some custom queries in Access to extract some kind of Kf for each map unit
- Review the SSURGO data model: http://soildatamart.nrcs.usda.gov/documents/SSURGO_2_2_DataModel_Part_1.pdf
- Each MapUnit contains several Components, each containing several Horizons.
- First query selects the surface horizons:
- - it joins tables muaggatt+component+chorizon,
- - joining on keys mukey and cokey
- - selecting only horizons whose hzdept_r is 0 (i.e. surface horizons)
- - includes the kffact (Kf-factor) and comppct_r (Percentage of map-unit occupied by Component) fields that will be used below
- Second query takes first as input, and is a MakeTable query, making the table that will be used in Arc
- - computes an expression 'yournamekf: Sum([comppct_r]*[kffact]/100)'
- - it is a Summation query, and the Summation is done on the yournamekf field (above)
- - the other two fields are musym and mukey, and they are GroupBy fields
- Run the second query; it will make a table
- Export the table to DBF format (one way of getting it to Arc)
- Back in Arc, add the DBF table as a layer
- Join the soilmu_a_ca069.shp layer to the DBF layer, using the mukey
- Change the soilmu_a_ca069.shp symbology to display quantitative based on the yournamekf field
Alternate versions
- None
