Improved Estimation of Splash and Sheet Erosion in Rangelands: Development and Application of a New Relationship and New Approaches for Sensitivity and Uncertainty Analyses

Persistent Link:
http://hdl.handle.net/10150/195122
Title:
Improved Estimation of Splash and Sheet Erosion in Rangelands: Development and Application of a New Relationship and New Approaches for Sensitivity and Uncertainty Analyses
Author:
Wei, Haiyan
Issue Date:
2007
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Soil erosion is a key issue in rangelands, but current approaches for predicting soil erosion are based on research in croplands and may not be appropriate for rangelands. An improved model is needed that accounts for the dominant erosion processes that operate in rangelands rather than croplands. In addition, effective application of such a model of rangeland erosion requires improved methods for assessing both model sensitivity and uncertainty if the model is to be applied confidently in natural resources management.I developed a new equation for calculating the combined rate of splash and sheet erosion (Dss, kg/m2) using existing rainfall-simulation data sets from the western United States that is distinct from that for croplands: Dss = Kss I 1.052q0.592, where Kss is the splash and sheet erosion coefficient, I (m/s) is rainfall intensity, and q (mm/hr) is runoff rate. This equation, which accounts for inter-relationship between I and q, was incorporated into a new model, the Rangeland Hydrology and Erosion Model (RHEM). This new model was better at predicting observed erosion rates than the commonly used, existing soil erosion model Water Erosion Prediction Project (WEPP).New approaches for assessing model uncertainty and sensitivity were developed and applied to the model. The new approach for quantifying localized sensitivity indices, when combined with techniques such as correlation analysis and scatter plots, can be used effectively to compare the sensitivity of different inputs, locate sensitive regions in the parameter space, decompose the dependency of the model response on the input parameters, and identify nonlinear and incorrect relationships in the model. The approach for assessing model predictive uncertainty, called "Dual-Monte-Carlo" (DMC), uses two Monte-Carlo sampling loops to not only calculate predictive uncertainty for one input parameter set, but also examine the predictive uncertainty as a function of model inputs across the full range of parameter space. Both approaches were applied to RHEM and yielded insights into model behavior.Collectively, this research provides an important advance in developing improved predictions of erosion rates in rangelands and simultaneously provides new approaches for model sensitivity and uncertainty analyses that can be applied to other models and disciplines.
Type:
text; Electronic Dissertation
Keywords:
Soil erosion; Rangeland; Sensitivity; Uncertainty; Modeling
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Natural Resources; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Breshears, David D.
Committee Chair:
Breshears, David D.; Nearing, Mark A.

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleImproved Estimation of Splash and Sheet Erosion in Rangelands: Development and Application of a New Relationship and New Approaches for Sensitivity and Uncertainty Analysesen_US
dc.creatorWei, Haiyanen_US
dc.contributor.authorWei, Haiyanen_US
dc.date.issued2007en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractSoil erosion is a key issue in rangelands, but current approaches for predicting soil erosion are based on research in croplands and may not be appropriate for rangelands. An improved model is needed that accounts for the dominant erosion processes that operate in rangelands rather than croplands. In addition, effective application of such a model of rangeland erosion requires improved methods for assessing both model sensitivity and uncertainty if the model is to be applied confidently in natural resources management.I developed a new equation for calculating the combined rate of splash and sheet erosion (Dss, kg/m2) using existing rainfall-simulation data sets from the western United States that is distinct from that for croplands: Dss = Kss I 1.052q0.592, where Kss is the splash and sheet erosion coefficient, I (m/s) is rainfall intensity, and q (mm/hr) is runoff rate. This equation, which accounts for inter-relationship between I and q, was incorporated into a new model, the Rangeland Hydrology and Erosion Model (RHEM). This new model was better at predicting observed erosion rates than the commonly used, existing soil erosion model Water Erosion Prediction Project (WEPP).New approaches for assessing model uncertainty and sensitivity were developed and applied to the model. The new approach for quantifying localized sensitivity indices, when combined with techniques such as correlation analysis and scatter plots, can be used effectively to compare the sensitivity of different inputs, locate sensitive regions in the parameter space, decompose the dependency of the model response on the input parameters, and identify nonlinear and incorrect relationships in the model. The approach for assessing model predictive uncertainty, called "Dual-Monte-Carlo" (DMC), uses two Monte-Carlo sampling loops to not only calculate predictive uncertainty for one input parameter set, but also examine the predictive uncertainty as a function of model inputs across the full range of parameter space. Both approaches were applied to RHEM and yielded insights into model behavior.Collectively, this research provides an important advance in developing improved predictions of erosion rates in rangelands and simultaneously provides new approaches for model sensitivity and uncertainty analyses that can be applied to other models and disciplines.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectSoil erosionen_US
dc.subjectRangelanden_US
dc.subjectSensitivityen_US
dc.subjectUncertaintyen_US
dc.subjectModelingen_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineNatural Resourcesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorBreshears, David D.en_US
dc.contributor.chairBreshears, David D.en_US
dc.contributor.chairNearing, Mark A.en_US
dc.contributor.committeememberNearing, Mark A.en_US
dc.contributor.committeememberGuertin, D. Phillipen_US
dc.contributor.committeememberStone, Jeffry J.en_US
dc.identifier.proquest2455en_US
dc.identifier.oclc659748377en_US
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