Modeling Regional Evapotranspiration for Forested Watersheds across the Southern United States

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dc.contributor.advisor Ge Sun, Committee Chair en_US Lu, Jianbiao en_US 2010-04-02T17:57:51Z 2010-04-02T17:57:51Z 2002-06-20 en_US
dc.identifier.other etd-06202002-150338 en_US
dc.description.abstract Evapotranspiration (ET) is the process that returns water to the atmosphere and therefore completes the hydrologic cycle. ET is a major component in the hydrological balance, and therefore is important to understanding forest water yield, sediment and nutrient movement. However, direct measurement of forest ET for a large region is not possible. The objectives of this study were to develop a model to estimate long-term annual actual evapotranspiration (AET) for forested watersheds across the southern United States (U.S.) and to compare the differences among six potential evapotranspiration (PET) methods. The developed AET model will be used to study hydrologic effects of climate and landuse changes. The six compared PET methods include three temperature-based methods (the Thornthwaite, Hamon and Hargreaves-Samani method) and three radiation-based methods (the Turc, Makkink and Priestley-Taylor method). A GIS database including land cover, hydrology and climate was developed for thirty-nine forested watersheds across the southern U.S.. Based on these data, a long-term annual AET model was developed. The independent variables included in the model are rainfall, latitude, elevation and percentage of land cover of conifer forests and water body in the watersheds. The model has a R2 of 0.85 and is sufficient to predict long-term annual AET for forested watersheds across the southern U.S.. Six PET methods were highly correlated but significantly different from each other. Greater differences were found among the temperature-based PET methods than radiation-based PET methods. In comparisons of the six PET methods, the Priestley-Taylor, Hamon and Turc methods performed better than the Thornthwaite, Makkink and Hargreaves-Samani methods. en_US
dc.rights I 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 NC State University 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.subject PET en_US
dc.subject modeling en_US
dc.subject forest hydrology en_US
dc.subject potential evapotranspiration en_US
dc.subject regional evapotranspiration en_US
dc.subject ET en_US
dc.subject evapotranspiration en_US
dc.title Modeling Regional Evapotranspiration for Forested Watersheds across the Southern United States en_US MS en_US thesis en_US Forestry en_US

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