Difference between revisions of "Carneros Watershed: Erosivity"
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== Processing Steps == | == Processing Steps == | ||
| − | + | 1.Download SSURGO data (fastest is from USDA GSG) | |
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| + | 2.Receive zip file of zip files, each one like soil_ca069.zip. | ||
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| + | 3.Extract, and open basic shapefile of map-units (MU): soilmu_a_ca069.shp in Arc | ||
| + | 4.Can't read tables in this zip, because need special MS Access Template | ||
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| + | 5.Download Access template from http://soildatamart.nrcs.usda.gov/templates.aspx | ||
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| + | 6.Open template in Access; Enable Macros; and it should prompt for location of your tables | ||
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| + | 7.Wait a few minutes while Access imports your tables | ||
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| + | 8.Create some custom queries in Access to extract some kind of Kf for each map unit | ||
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| + | 8a. Review the SSURGO data model: http://soildatamart.nrcs.usda.gov/documents/SSURGO_2_2_DataModel_Part_1.pdf | ||
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| + | 8b. Each MapUnit contains several Components, each containing several Horizons. | ||
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| + | 8c. First query selects the surface horizons: | ||
| + | 8c1 - it joins tables muaggatt+component+chorizon, | ||
| + | 8c2 - joining on keys mukey and cokey | ||
| + | 8c3 - selecting only horizons whose hzdept_r is 0 (i.e. surface horizons) | ||
| + | 8c4 - includes the kffact (Kf-factor) and comppct_r (Percentage of map-unit occupied by Component) fields that will be used below | ||
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| + | 8d. Second query takes first as input, and is a MakeTable query, making the table that will be used in Arc | ||
| + | 8d1 - computes an expression 'fredkf: Sum([comppct_r]*[kffact]/100)' | ||
| + | 8d2 - it is a Summation query, and the Summation is done on the fredkf field (above) | ||
| + | 8d3 - the other two fields are musym and mukey, and they are GroupBy fields | ||
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| + | 8e. RUn the second query; it will make a table | ||
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| + | 8f. Export the table to DBF format (one way of getting it to Arc) | ||
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| + | 9.Back in Arc, add the DBF table as a layer | ||
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| + | 10.Join the soilmu_a_ca069.shp layer to the DBF layer, using the mukey | ||
| + | |||
| + | 11.Change the soilmu_a_ca069.shp symbology to display quantitative based on the fredkf field | ||
== Links == | == Links == | ||
* [[Maps of the Carneros Watershed]] | * [[Maps of the Carneros Watershed]] | ||
Latest revision as of 16:15, 10 February 2011
[[Image:|200px|thumb]]
- [[Media:|PDF file - for printing]]
- [[Media:|JPG file]]
Metadata
- Data Source: USGS, 1/3 arc second, Digital Elevation Model: See Carneros Watershed: Map of Elevation
- Data analysis: ArcMap
- Map produced by: Kathy
- Coordinate system: UTM Zone 10
- Datum: NAD 83
Processing Steps
1.Download SSURGO data (fastest is from USDA GSG)
2.Receive zip file of zip files, each one like soil_ca069.zip.
3.Extract, and open basic shapefile of map-units (MU): soilmu_a_ca069.shp in Arc 4.Can't read tables in this zip, because need special MS Access Template
5.Download Access template from http://soildatamart.nrcs.usda.gov/templates.aspx
6.Open template in Access; Enable Macros; and it should prompt for location of your tables
7.Wait a few minutes while Access imports your tables
8.Create some custom queries in Access to extract some kind of Kf for each map unit
8a. Review the SSURGO data model: http://soildatamart.nrcs.usda.gov/documents/SSURGO_2_2_DataModel_Part_1.pdf
8b. Each MapUnit contains several Components, each containing several Horizons.
8c. First query selects the surface horizons: 8c1 - it joins tables muaggatt+component+chorizon, 8c2 - joining on keys mukey and cokey 8c3 - selecting only horizons whose hzdept_r is 0 (i.e. surface horizons) 8c4 - includes the kffact (Kf-factor) and comppct_r (Percentage of map-unit occupied by Component) fields that will be used below
8d. Second query takes first as input, and is a MakeTable query, making the table that will be used in Arc 8d1 - computes an expression 'fredkf: Sum([comppct_r]*[kffact]/100)' 8d2 - it is a Summation query, and the Summation is done on the fredkf field (above) 8d3 - the other two fields are musym and mukey, and they are GroupBy fields
8e. RUn the second query; it will make a table
8f. Export the table to DBF format (one way of getting it to Arc)
9.Back in Arc, add the DBF table as a layer
10.Join the soilmu_a_ca069.shp layer to the DBF layer, using the mukey
11.Change the soilmu_a_ca069.shp symbology to display quantitative based on the fredkf field
