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dc.contributor.authorWagner, Rachel Cainen_US
dc.description.abstractThis research addresses the Reference Watershed Approach (RWA) in the TMDL process for benthic impairments. In the RWA, do different land use sources (DOQQ and NLCD) or use of alternative water quality models (GWLF and SWAT) result in different stressor loadings? Is there a difference in stressor loadings when different reference watersheds are used?

Study results showed that using different land use sources resulted in required stressor reductions that were different by greater than 10%. In one scenario, use of the NLCD-based land use parameters results in 3.5 times greater reductions than use of DOQQ-based land use parameters. With respect to water quality model selection, in two of the three scenarios considered, a difference in stressor reduction requirements of greater than 10% resulted from using different models. Differences in load reduction requirements are also seen when different reference watersheds are used, regardless of the water quality model or the land use source used. Different references result in a difference of as much as 73% in required sediment reductions in the impaired watershed: the required reductions using one reference watershed are 6.2 times as great as when another is used.

Possible alternatives to the RWA include water quality standards to set the target level for many of the common stressors on the benthic assemblage, regression equations that relate benthic stressors to the RBP II score, or averaging of stressor reduction requirements obtained from using the Reference Watershed Approach on several different reference watersheds.
dc.publisherVirginia Techen_US
dc.rightsI hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Virginia Tech or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report.en_US
dc.subjectbenthic impairmenten_US
dc.subjectwater qualityen_US
dc.subjectwater quality modelen_US
dc.subjectReference Watershed Approachen_US
dc.titleAn Examination of the Reference Watershed Approach for TMDLs with Benthic Impairmentsen_US
dc.contributor.departmentBiological Systems Engineeringen_US
dc.description.degreeMaster of Scienceen_US of Scienceen_US Polytechnic Institute and State Universityen_US Systems Engineeringen_US
dc.contributor.committeechairDillaha, Theo A. IIIen_US
dc.contributor.committeememberVoshell, J. Reese Jr.en_US
dc.contributor.committeememberYagow, Eugene R.en_US
dc.contributor.committeememberMostaghimi, Saieden_US

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