Presentation on theme: "Modeling, and Soil Survey"— Presentation transcript:
1Modeling, and Soil Survey SinkholesModeling, and Soil Survey
2ObjectivesExamine a few techniques and efforts to model karst features for map unit and/or component delineation.Consider some case studies of mapping and updating karst areas:Lawrence co, IndianaSpringfield plateau, Missouri
3GIS techniques to enhance identification of karst Karst: Dade county, MO
6Flowaccumulation (multi-path): karst area Source: F. Young, NRCSDidn’t work that well…
7Karst: wetness index (multi-path) Bluer = higher wetness index.Works fairly well for some sinkholes.However, not all upland wet areas are sinkholes.
8Can we model these sinkholes? Moderately high elevationAvg about 325m; range about 315 to 335mHigh Flow accumulationAbove about 200High Wetness IndexAbove about 9Not on the stream networkNot so easy to modelSource: F. Young, NRCS
9Fuzzy Membership Model for Sinks Higher-elevation valleys confounded w sinksModeled using SIE: Full membership = 100.What about using streams in the model?USGS streams layer is incomplete (missing tributaries)Modeled stream network runs into sinks
10Fuzzy Membership Model w more restrictive lower elevation criteria (lost the lowest elevation sinkhole)
11Karst plain: Pierpont area, Boone county, MO Source: F. Young, NRCS
12Simple Fuzzy Membership model for Pierpont sinkhole areas: High elevation (full membership above 225m)High wetness index (full membership above 5)Source: F. Young, NRCSDoes an OK job of identifying areas where the sinkholes occur
13Mapping karst in SSURGO How can we identify karst features in…Spatial dataAttribute dataHow might this affect interpretations?Case studies: karst in soil surveyLawrence county, INSpringfield Plateau (MLRA 116B), MODiscussion; see possible answers in last slide (AFTER discussion, please!)
14Karst mapping: Lawrence county, IN Acknowledgements: Dena Marshall (now Lexington KY)Genny Helt (Indianapolis IN)
15Physiographic Features of southern Indiana (Schneider, 1966) Source: Schneider, A.F Physiography. P in A.A. Lindsey, ed. Natural features of Indiana. Indiana Acad. Sci., Indiana State Library, Indianapolis
16A closer look at features of the Crawford Upland & Mitchell Plain Source: Dena Marshall, NRCS, Lexington KYA closer look at features of the Crawford Upland & Mitchell Plain
17KY & IN Sandstone & Shale Hills & Valleys Lawrence county- 30m DEM- MLRAsHow do the lines look?Where’s the karst?Highland Rim & PennyroyalKY & IN Sandstone & Shale Hills & Valleys
18Physiographic Regions Mitchell Plain:middle Mississippian- aged limestonesNorman UplandMitchell PlainCrawford Upland
19Karst map units in Lawrence county, IN Note: no sinkhole spot symbols
20The karst soils in Lawrence county “Terra rossa”Loess over “residuum” (in situ?)CriderFi-si Typic Paleudalfs10R w depthKnobcreek (Frederick correlated to this in IN)Fi-si / clayey Typic PaleudalfsNot as redThe limestone in this area is probably too clean to have produced enough residuum in-place to create these soils.
21Mapping patterns & rules Limestone underlain w siltstone: little/no karst.Limestone thickens westerly; sinkholes appear.IN Geomorphology Tour “some years ago”:Karst map unit:Areas w sinkhole density of > 1 per 5 acresSpot symbol:Sinkhole density < 1 per 5 acresRef: Pers. Comm., Dena Marshall, SS, currently Lexington KY
22Attributes (NASIS soil properties) Bedrock in a karst component within 80”Higher Ksat than corresponding non-karst unitEntry for Ksat in R layerE.g., Navilleton components, Floyd co IN:Karst component: R Ksat 1.42 –Non-karst component: R ksat 0.43 – 42.34Bedrock below 80”No known differences in soil properties between karst and non-karst map unitsIf we could populate soil property data below 80”, there would be differences.
23MLRA Soil Survey Project: Updating Karst Areas on the Springfield Plateau (MLRA 116B) County-based soil surveys (over 40+ years) handled karst in various ways.Ignored in some,Spot symbols in some,Karst map units in some.Inconsistent use of all of the above, both within and among counties.Springfield Plateau
24Karst Project: Methodology Primarily a GIS office projectUtilize:Elevation dataDEMs, Hypsography linesExisting SSURGOOrthophotosSinkholes layer (statewide; USGS)On-screen digitizing/editing of SSURGOEstablish new map units“Karst” in name, orSoil series that occur only in sinkhole basins.
25Results: 20 new map units in 7 counties “Karst” map units; e.g.,Goss grsil, karst, 8-15%Sinkhole basin map units; e.g.,Lowassie sil, 0-3%, freq. pondedZoom in to this area (next slide)
26Sinkholes point layer over 10m DEM, with SSURGO polygons
27Map units added in this area Blue = sinkhole basin units; Red = “Karst” in MU Name
28Karst discussion “answers” Spatial identification of karst:Map unit phases (i.e., “karst” in muname).Spot symbols.Map units named by components that only occur in karst (i.e., no need for “karst” in muname).e.g., in Missouri: Lowassie, Grandgulf series only occur in sinkholes.Attribute interpretationMuname contains “karst”Component geomorphic description table: landform = “sinkhole”Differences in soil properties?InterpretationsPossibility for groundwater contaminationOnsite wastewater disposal; lagoons; others?Not keyed in standard National Interps (?)Custom, state-created interps (e.g., MO onsite wastewater interp)Keys on “karst” in the muname, and “sinkhole” landform