Difference between revisions of "Carneros Watershed: Map of Soil Erodibility Index"
| Line 12: | Line 12: | ||
* Coordinate system: Geographic Coordinate System - GCS_North_American_1983 | * Coordinate system: Geographic Coordinate System - GCS_North_American_1983 | ||
* Datum: D_North_American_1983 | * Datum: D_North_American_1983 | ||
| + | |||
| + | == Data Analysis Steps Taken == | ||
| + | |||
| + | 1. Download SSURGO data | ||
| + | 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 'yournamekf: 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 yournamekf field | ||
== Alternate versions == | == Alternate versions == | ||
Revision as of 21:52, 27 February 2011
Metadata
- Original source of data: SSURGO
- Data analysis: Fred Watson and Kathy Pugh
- 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
1. Download SSURGO data 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 'yournamekf: 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 yournamekf field
Alternate versions
- None
