| This research, focused on semi-distributed physically-based hydrological modeling in the tropics and subtropics, is represented in three parts. Part one aims to vigorously evaluate the performance of hydrologic model in simulating the hydrologic response of a subtropical data-rich gauged basin in the U.S., the Upper Kentucky River basin. Part two examines the performance and reliability of the validated model in a tropical data-poor ungauged basin in Central Vietnam, the Huong River basin. This part also studies total suspended solids concentration simulation beside river discharge and indentifies possible anthropogenic impacts on natural river flow. Part three is an assessment of water availability in the Vietnam basin for the twenty first century driven by projected climatic data from different Global Climate Models. The hydrologic model that is used in this research is the Soil and Water Assessment Tool (SWAT), a semi integrated physically-based watershed model. Hydrological modeling in this research takes advantage of the recent advances in Geographic Information Systems and Remote Sensing and employs publicly available products such as climatic data and Global Climate Model projections.;Research results suggest that the SWAT model has good performance in the Upper Kentucky River basin and has the capability of reproducing daily discharge in alternative time periods and locations of the river. However, the SWAT model, driven by remotely sensed inputs, can only reasonably simulate runoff processes in absence of ground observations as in the Huong River basin. The study's results also indicate the continuous increase in summer and fall discharge of Huong River within the twenty-first century in A2 and B1 scenarios. In A1B scenario, HadCM3 and GFDL-CM2.1 models predict a decrease in river discharge from present to 2060s and then increase until 2080s; while ECHAM5-OM model produces opposite projection that discharge will increase until 2060s and then decrease for the rest of the century. |
