Doctor of Philosophy, The Ohio State University, 2010, Environmental Science

Conservation management practices are considered one of the best answers to escalating water quality deterioration by nonpoint source pollution. Integrated watershed economic model (IWEM) offers a multidisciplinary framework by addressing both the biophysical and the economic (cost and benefit) aspects of water quality improvement. An IWEM would have: a watershed model, an economic model, and an integration tool. Components of IWEM were translated into three essays of the dissertation and applied to the Upper Big Walnut Creek (UBWC) watershed in central.The modeling of the UBWC watershed was performed in the first essay. Soil and Water Assessment Tool (SWAT) was used to predict the nutrient export associated with land management practices. A new integrated calibration procedure was introduced for the calibration and validation of the UBWC watershed model. The predicted flow for daily, monthly and annual time scales were not statistically different from the measured values. Moreover, the predicted crop yield was also not statistically different from the reported values. Nitrate fluxes, calibrated using the field measured values at the two paired sub-watersheds, predicted nitrate loading was statistically not different from the measured values. The uncertainty analysis showed that the model predicted flow and nitrate load was with the lowest uncertainty. Recreational value of water quality improvement was estimated in second essay by using a combined revealed and stated preference method with baseline dependence and unobserved heterogeneity modeling. A mailed survey method was used to collect data, in which 1400 registered anglers and licensed boaters in 5 surrounding counties of the watershed were selected for the study. The baseline average number of trips was 2.35, which was reduced to 1.72 with more information about pollution level in the watershed. However, water quality improvement would increase the number of trips to 2.78. The average annual consumer surplus (open full item for complete abstract)

Committee: Brent Sohngen D.F (Advisor); Douglas Southgate PhD (Committee Member); Fausey Norman PhD (Committee Member); Kevin King PhD (Committee Member); Jonathan Witter PhD (Committee Member) Subjects: Agricultural Economics; Environmental Science