Soil Data for Riverbank Erosion August 30, 2018 | David Rand What - - PowerPoint PPT Presentation

Soil Data for Riverbank Erosion

August 30, 2018 | David Rand

S o i l S c i e n c e D i v i s i o n

What is SSURGO soil data?

• Soil materials and layers
• texture, rock fragments, depth, pH
• Site characteristics
• landform, slope, climate, potential

vegetation

• Location (maps)
• Facilitates prediction and extrapolation of

soil behavior

• SSURGO database available online through

Web Soil Survey

• Intended for natural resource planning and

management by landowners and counties

• Scale is important

• Fig. 3 from Soil Survey of Marion County Area, Oregon. https://www.nrcs.usda.gov/Internet/FSE_MANUSCRIPTS/oregon/marionOR1972/marionOR1972.pdf

How is SSURGO soil data made?

Soil Interpretations

• Boil down the data
• Evaluate suitability for particular soil uses
• Based on rule sets
• Web Soil Survey offers standard interpretations
• E.g. “Shallow Excavations” evaluates
• coarse material
• shrink/swell
• water table
• A standard interpretation for wake erosion vulnerability

hasn’t been developed yet

• Need to investigate which soil properties translate to bank erosion

vulnerability

Locating vulnerable soils… a preliminary interpretation

Observation/Hypothesis: Soils exposed in cut banks vulnerable to erosion are silty or

• clayey. These soils are cohesive enough to form a vertical bank,

but they may be gradually undermined until the bank collapses.

• Soil data can’t test this hypothesis
• Soil data CAN show the extent of silty or clayey soils

Locating vulnerable soils…a preliminary interpretation

Closing Thoughts

• SSURGO soil data summarizes soil properties and site

characteristics under natural conditions

• Doesn’t account for man-made or recent manipulations
• Rip rap, vegetation, channel geometry
• Soil data should be interpreted based on tested rule sets as

knowledge grows about wave erosion in the Newberg Pool

• USDA-NRCS can continue to assist in accessing and arraying

soil data