aquifer vulnerability assessment: project review columbia county june 11, 2009 columbia county,...

AQUIFER VULNERABILITY ASSESSMENT: AQUIFER VULNERABILITY ASSESSMENT: PROJECT REVIEW COLUMBIA COUNTY PROJECT REVIEW COLUMBIA COUNTY

June 11, 2009June 11, 2009Columbia County, FloridaColumbia County, Florida

Advanced GeoSpatial Inc.Advanced GeoSpatial Inc.Alan Baker, P.G.Alan Baker, P.G.James CichonJames Cichon

Presentation OverviewPresentation Overview Conceptual Conceptual

DefinitionDefinition Model ResultsModel Results Implementing Model Implementing Model

ResultsResults Generalization with Generalization with

examplesexamples

Model LimitationsModel Limitations Vulnerability is relative; all aquifers are Vulnerability is relative; all aquifers are

vulnerablevulnerable Based on features of the natural system that Based on features of the natural system that

have association with location aquifer have association with location aquifer vulnerability vulnerability

Does not account for human activityDoes not account for human activity Does not take account for contamination Does not take account for contamination

typestypes Does not estimate ground-water flow pathsDoes not estimate ground-water flow paths Does not model fate/transport of chemical Does not model fate/transport of chemical

constituentsconstituents Large surface water features omittedLarge surface water features omitted

Study Area Study Area over which over which to search for to search for a particular a particular occurrenceoccurrence

Usually a Usually a county or county or some some political political boundaryboundary

Can be Can be aquifer or aquifer or springshed springshed specific specific

Conceptual DefinitionConceptual Definition

Development Development of evidential of evidential layers used as layers used as predictors:predictors: Soil PropertiesSoil Properties Confinement Confinement

or Overburden or Overburden ThicknessThickness

Sinkhole Sinkhole Features or Features or closed closed topographic topographic depressionsdepressions


Training SitesTraining Sites Dataset of Dataset of

occurrences in our occurrences in our case ground water case ground water wellswells

Maximize Maximize knowledge by knowledge by locating as many as locating as many as possible possible

Evaluate water Evaluate water quality records to quality records to locate upper locate upper quartilequartile

Ultimately use a Ultimately use a subset of total wellssubset of total wells


Conceptual ModelConceptual Model

Evidential layers are Evidential layers are spatially associated spatially associated with the distribution with the distribution of known of known occurrences and occurrences and then generalized then generalized into binary pattersinto binary patters

Individual evidence Individual evidence layers are combined layers are combined together as a map together as a map depicting the best depicting the best areas to search for areas to search for contaminationcontamination

Use known Use known locations and locations and assess their assess their distribution distribution spatially with spatially with respect to each respect to each factor causing factor causing occurrence occurrence

Where are the Where are the relationships or relationships or breaks between breaks between the data and the the data and the training points?training points?

Conceptual ModelConceptual Model

InputInput Soil Soil

PermeabilityPermeability Overburden Overburden

ThicknessThickness Hydraulic Hydraulic

Head Head DifferenceDifference

Karst Karst FeaturesFeatures

Soil permeabilitySoil permeability Determine spatial Determine spatial

association association between theme between theme and training and training pointspoints

Analysis reveals Analysis reveals that highest that highest contrast occurs at contrast occurs at a soil permeability a soil permeability rate of 7.66 in/hrrate of 7.66 in/hr

Overburden Overburden thicknessthickness

Determine spatial Determine spatial association association between theme between theme and training and training pointspoints

Analysis reveals Analysis reveals that highest that highest contrast occurs contrast occurs at a overburden at a overburden thickness of 117 thickness of 117 feetfeet

Karst FeaturesKarst Features Determine Determine

spatial spatial association association between theme between theme and training and training pointspoints

Analysis reveals Analysis reveals that highest that highest contrast occurs contrast occurs at a distance of at a distance of 210 m from a 210 m from a karst featurekarst feature

Aquifer Vulnerability Aquifer Vulnerability MapsMaps

We now have a map We now have a map showing where to focus showing where to focus our efforts in similar our efforts in similar locations locations

Results are based on data Results are based on data collected about existing collected about existing occurrences occurrences

Model reveals a map Model reveals a map showing favorable areas showing favorable areas with greater probablity of with greater probablity of finding occurrencefinding occurrence

Relative Vulnerability

Vulnerable

More Vulnerable

Most Vulnerable

Local versus Local versus regional regional

assessmentassessment Larger scale study area: Larger scale study area:

Wekiva Aquifer Wekiva Aquifer Vulnerability Vulnerability AssessmentAssessment

Results are normalized Results are normalized across smaller study across smaller study area, not entire area, not entire statewide extent of statewide extent of aquifer systemaquifer system

Can include refined Can include refined input data such as input data such as LIDARLIDAR

Provides more usable Provides more usable final product for final product for planners, developers, planners, developers, regulators, and local regulators, and local government government

Local versus RegionalLocal versus Regional

Aquifer Vulnerability Aquifer Vulnerability Assessment BenefitsAssessment Benefits

Assists local government, planners and Assists local government, planners and developers in guiding growth into areas developers in guiding growth into areas delineated as lower vulnerabilitydelineated as lower vulnerability

Enables more focused protection of sensitive Enables more focused protection of sensitive areas, e.g., springsheds and ground-water areas, e.g., springsheds and ground-water recharge areas recharge areas

Public tax dollars used more wisely as a resultPublic tax dollars used more wisely as a result Has be used to help guide wastewater Has be used to help guide wastewater

management requirements – septic zones vs. management requirements – septic zones vs. centralized sewercentralized sewer Leon County & Alachua CountyLeon County & Alachua County

Purpose, End Users, and BenefitsPurpose, End Users, and Benefits

Implementing model Implementing model resultsresults

Results are not static; model is based Results are not static; model is based on best available data and is on best available data and is snapshot in timesnapshot in time

New and refined data reveals more New and refined data reveals more accurate or complex statistical accurate or complex statistical patterns allowing higher confidence patterns allowing higher confidence in resultsin results Lidar: Karst and OverburdenLidar: Karst and Overburden

Accuracy is function input dataAccuracy is function input data Approach is highly adaptable and Approach is highly adaptable and

useful tool for implementing ongoing useful tool for implementing ongoing protection of ground-water resourcesprotection of ground-water resources

Implementing Model ResultsImplementing Model Results

Alachua and Leon Counties contracted Alachua and Leon Counties contracted with AGI for development of derivative with AGI for development of derivative protection-zone maps based on each of protection-zone maps based on each of the County Aquifer Vulnerability the County Aquifer Vulnerability ModelsModels

Deliver an aquifer protection zone map Deliver an aquifer protection zone map based on individula results that is based on individula results that is directly applicable to land use and directly applicable to land use and environmental regulatory decisionsenvironmental regulatory decisions

Generalization of CAVA Model Generalization of CAVA Model ResultsResults

MethodologyMethodology

Generalization of the vulnerability Generalization of the vulnerability map into specific aquifer protection map into specific aquifer protection zoneszones Raster Smoothing techniques employedRaster Smoothing techniques employed Help guide implementation Help guide implementation

Avoid use of results on parcel to parcel scaleAvoid use of results on parcel to parcel scale Account for highly resolved but isolated Account for highly resolved but isolated

areas of vulnerability areas of vulnerability Use of ArcGIS Spatial Analyst Use of ArcGIS Spatial Analyst

extensionextension

Determination of Determination of Appropriate Analysis Appropriate Analysis

WindowWindow Recent projects recommended that model Recent projects recommended that model

results be applied on a local scale of greater results be applied on a local scale of greater than or equal to approximately 1.0 mithan or equal to approximately 1.0 mi22 for for statewide studies (Florida Aquifer statewide studies (Florida Aquifer Vulnerability Assessment) Vulnerability Assessment)

Or approximately 0.75 miOr approximately 0.75 mi22 for localized for localized studies (Alachua, Wekiva, Leon and Marion studies (Alachua, Wekiva, Leon and Marion County Aquifer Vulnerability Assessments). County Aquifer Vulnerability Assessments).

Based on similarities to larger scale projects, Based on similarities to larger scale projects, AGI determined that model results be used at AGI determined that model results be used at a recommended scale of 0.75 mia recommended scale of 0.75 mi22, or an , or an approximate 4,500-ft grid cell size. approximate 4,500-ft grid cell size.

ACAVA Model ResultsACAVA Model Results

!( DO Training Points

DO Model - Final Results

Logistic Regression

Most Vulnerable

More Vulnerable

Vulnerable

Less Vulnerable

Draft test resultsDraft test resultsFocal Mean

Filters on a window with a radius of 12 cells

Cell size is 345 m.

Calculates a statistic on a raster over a specified neighborhood. Focal Mean Finds the mean of the values for each cell location on an input raster within a specified neighborhood and sends it to the corresponding cell location on the output raster.

http://www.1000friendsofflorida.org/water/WakPowerPoits/Wayne%20Tedder%20TLCPD%20Wakulla%20Springs%20Workshop.ppt.pdf

Note on CCAVANote on CCAVA

Protection zone map will be a Protection zone map will be a derivative product of the original derivative product of the original model CCAVA resultsmodel CCAVA results

Not intended as a replacement of Not intended as a replacement of the CCAVA resultsthe CCAVA results

As a result, the protection zone map As a result, the protection zone map will represent a standalone map will represent a standalone map product based on CCAVA results and product based on CCAVA results and additional supplemental datasetsadditional supplemental datasets

1949 Raymond Diehl Rd, 1949 Raymond Diehl Rd, Ste. DSte. D

Tallahassee, FL 32308Tallahassee, FL [email protected]@adgeo.net

850/580-4GIS850/580-4GIS

aquifer vulnerability assessment: project review columbia county june 11, 2009 columbia county,...

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