| Hydrological characteristics of a watershed are dependent on a variety of factors, including the local climate, land use, soil, and other anthropogenic influences. Changes in these factors unequivocally would affect the water resources. To ensure that we will have adequate water supply in the future, we need a methodology that would enable us to predict the hydrologic ramifications caused by potential changes of the above mentioned factors. Furthermore, there is a need for new integrative approaches that model not only the separate but also the combined impacts of these changes as they act in tandem with each other. It is also important to understand the relationships between different variables and the underlying watershed processes under different environmental settings in order to adapt, respond, and make efficient water resource management decisions.;The watershed hydrologic model, the Hydrological Simulation Program-FORTRAN (HSPF) and Normalized Root Mean Square Error (NRMSE) technique with Flow Duration Curve analysis were employed in this dissertation research project as the major assessment tools. These tools were applied to two watersheds, the Little Miami River (LMR) and the Las Vegas Wash (LVW) watersheds that are located under different hydro-climatic settings. From the results, it seemed that the tool developed could be helpful in facilitating the prediction of the plausible hydrologic consequences of climate, population, and land use changes. The simulation results also highlighted the extent to which different global change factors could amplify the hydrologic effects at a watershed scale. Moreover, the results revealed that the hydrology in the LMR watershed is mostly sensitive to groundwater related parameters, whereas the LVW watershed is related to near surface soil parameters. Furthermore, high and medium flows are the most sensitive flow regimes to most of watershed processes.;The objectives of this dissertation are (i) to develop a tool/protocol to better understand the watershed systems and to help planners/resource managers to explore and predict the impacts of potential changes in climate, land use, and population, through basin scale watershed modeling; (ii) to introduce a total water management approach to help in managing the future potential changes in demand and supply of water; and (iii) to develop an approach to investigate the watershed characteristics and processes that control the hydrologic behaviors of the watersheds. |
