DRASTIc Groundwater Vulnerability map of Tennessee
Click here to load reader
Embed Size (px)
Transcript of DRASTIc Groundwater Vulnerability map of Tennessee
DRASTIC GROUNDWATER VULNERABILITY MAP OF TENNESSEEJames Bond Capstone ProposalGEOG 596A
Overview of PresentationIntroductionMethodologyAnticipated Results & ProblemsReferences
IntroductionMy ProjectDRASTIC Groundwater Vulnerability Map of TennesseeDRASTICWhat is it?Identifies areas where groundwater is susceptible to pollutionWhat are the applications?Guides land development & resource protectionFlexibleUsed at a variety of scalesCan be modified to include or exclude parameters
Example DRASTIC Map
DRASTIC OverviewDRASTIC methodology guided by EPADeveloped by EPA & National Water Well Assoc.600+ page guidance documentLink to Guidance:http://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=20007KU4.txtPurpose Over large areas, used to identify regions where groundwater is more or less susceptible to impact from pollution.
DRASTIC Overview Cont.Overview of DRASTICSimplified GW vulnerability modelQualitativeProduces a relative-risk scaleApplicable over large areasUsed as a screening toolResults guide land development & resource protectionFor small, specific sites, more detailed assessment needed
DRASTIC Method AssumptionsDRASTIC Makes Four Assumptions:Contamination is introduced at the ground surfaceContamination is flushed into the groundwater by precipitationContamination has the mobility of waterArea being evaluated is 100-acres or largerIf these assumptions are not met, then DRASTIC is not the appropriate methodology
DRASTIC FactorsSeven hydrogeologic factors used. They form the acronym DRASTICD Depth to WaterR Net RechargeA Aquifer MediaS Soil MediaT TopographyI Impact of Vadose Zone MediaC Hydraulic Conductivity of Aquifer
Weights & RatingsSignificance of each factor in contaminant transport variesRelative weight is assigned to each factorScale of 1 to 51 is least important factor5 is most important factorEach factor also has a rating applied according to a category or range of values.
DRASTIC The EquationOnce ratings and weights have been applied, they are multiplied and addedDRASTIC equation:
DrDw + RrRw + ArAw + SrSw + TrTw + IrIw + CrCw = Pollution Potentialr = ratingw = weight
Results are symbolized on a map overlaying study area
Methodology - ExampleExample of how ratings and weights are appliedWill use D Factor (Depth to Water) as exampleD receives a weight of 5It is very significant in potential impact to GWBased on actual depth to groundwater, D also receives a rating.
Methodology Example Cont.If depth to water was 10 ft then D rating would be 9DrDw = 9 x 5 = 45
If depth to water was 100 ft, then D rating would be 2DrDw = 2 x 5 = 10
This process is repeated for each of the factors
Data Analysis Process
Self-Imposed Project ParametersDue to time constraints, need to impose parameters on the analysis Use unmodified version of methodUse existing datasets as much as possibleTo fill datagaps will use the easier of two approaches:Derive missing data from other existing dataUse generalized values in EPA guidance
ANTICIPATED RESULTS & PROBLEMS
Anticipated ResultsState of TN groundwater vulnerability mapDetailed report of methodology and data usedMap will be technically correctConsidered FINAL within context of capstone projectConsidered DRAFT by public and professionals who may use it
Anticipated ProblemsLow Resolution DataAnticipate using only small scale dataMissing dataNot all inputs may be availableMay have to infer data or use generalized inputsRoom for improvementAnalysis can be easily re-run with better dataBetter data = better resultsAdditional refinement outside the scope of this capstone project
SummaryProject to produce groundwater vulnerability map of TennesseeHas not been done for TennesseeUse EPA DRASTIC vulnerability methodologyUse small scale, publicly available dataResult will be a first cut at groundwater vulnerability mappingModel will have room for refinementOutside the scope of this project
ReferencesU.S. EPA DRASTIC Guidance DocumentUnited States Environmental Protection Agency (EPA), 1987, DRASTIC: A Standardized System for Evaluating Ground Water Pollution Using Hydrogeologic Settings, EPA/600/2-87-035, Robert S. Kerr Environmental Research Laboratory, Ada, OK 74820
Examples of the Application of DRASTICArthur, Jonathan D., et al., 2005, Florida Aquifer Vulnerability Assessment (FAVA): Contamination Potential of Floridas Principal Aquifer Systems, Division of Resource Assessment and Management, Florida Geological SurveyChowdhury, Shafiul, et al, 2003, Comprehensive approach of groundwater resource evaluation: a case study in the Chippewa Creek watershed in Ohio, The Ohio Journal of Science, December 2003Crider, S.S., 1989, A Cursory Application of DRASTIC to the Savannah River Site, WSRC-RP-89-744, DE92 009778, Division of Engineering Fundamentals, Virginia Polytechnic Institute and State University, Blacksburgh, VA 24061-0218Evans, Barry, et al, 1990, A GIS-Based Approach to Evaluating Regional Groundwater Pollution Potential with DRASTIC, Journal of Soil and Water Conservation, March-April, pp. 242-245Rupert, Michael G., 1999, Improvements to the DRASTIC Ground-Water Vulnerability Mapping Method, USGS Fact Sheet FS-066-99, Department of the Interior, US Geological Survey, Denver, CO 80225
*Introduction Will state the goal of my project and give an introduction to DRASTIC
Methodology Will provide a more detailed look at DRASTIC. Will discuss: method development, give examples of its application, provide a detailed look at the method itself. Will also discuss the general process I plan to follow for carrying out the project, including constraints and limitations that I will have.
Anticipated Results & Problems will discuss what I hope to end up with, what problems I expect that I may encounter, and how my results can be improved upon.
References A list of sources, primarily from the examples, but the important one is the EPA method document.*The goal of my project is to produce a DRASTIC groundwater Vulnerability map of Tennessee. Internet research and conversation with TN Department of Env. Conservation (TDEC) has not revealed any instances where this has been done for TN.
DRASTICWhat is it? Anyone who took GEOG 487 Environmental Applications of GIS with Ken Corridini probably remembers DRASTIC. It is a method used to identify areas where the groundwater is more or less susceptible to impact from pollution.What are the applications? Used to guide land development and resource protection. It can be used on a variety of scales, including sites (if they are large enough) such as the Savannah River Site in South Carolina, watersheds such as the Chippewa Creek watershed in OH, and states such as Pennsylvania.It can be modified to include or exclude parameters such as nitrates and pesticides as in the study conducted on the Snake River Basin, ID. It can also serve as the basis for new methods as in the Florida Aquifer Vulnerability Assessment *Here is an example of a DRASTIC Map. The lighter areas are more susceptible to contamination.*The DRASTIC method was developed by the EPA and the National Water Well Association. According to the EPA DRASTIC guidance document (EPA, 1987), DRASTIC is a qualitative method that is intended to be used over large areas as a way to begin to understand which areas are more or less likely to be impacted by contamination from the surface migrating into aquifers. *Simplified model DRASTIC is a relatively simple model compared to many other vulnerability models. Requires relatively fewer data inputsQualitative results are qualitative.Qualitative results produce a relative-risk scaleApplicable to large areasScreening toolResults can guide general land development & resource protection decisionsFor small areas, more detailed assessment is needed.
The DRASTIC method was developed by the EPA and the National Water Well Association as a way to produce a relative-risk scale of potential groundwater vulnerability to pollution that could be applied to a large area, while requiring relatively little data compared to other vulnerability models. According to the EPA DRASTIC guidance document (EPA, 1987), DRASTIC is a qualitative method that is intended to be used over large areas as a way to begin to understand which areas are more or less likely to be impacted by contamination from the surface migrating into aquifers. Due to the relative simplicity of DRASTIC compared to some other vulnerability assessment models, the large scale for which it is intended, and the qualitative nature of the results, DRASTIC should be thought of as a screening tool or as a coarse-grained look at aquifer vulnerability modeling that helps guide decisions and focus resources on areas that may require more detailed analyses, whether for land use decisions or environmental protection. Although DRASTIC is useful over large areas and serves as a good first step, ultimately, when making site-specific decisions on small, local areas, additional detailed site-specific hydrogeologic modeling of contamination potential would be considered as an appropriate next step.
*In order for DRASTIC to be properly utilized and the results of the DRASTIC analysis to be fully understood, it is necessary to understand the assumptions that the method makes. The four key assumptions are:Contamination is introduced at the ground surfaceContamination is flushed into the groundwater by precipitationContamination has the mobil