The purpose of this study is to establish the procedure and evaluation methods for total mass control in water quality, which can be applied to environmental impact assessment. This study uses water quality simulation and optimization models to develop unit area pollutant load for different land uses with considering environmental carrying capacity and cumulative impacts. Different water quality models are reviewed. The HSPF, QUAL2E, GWLF models are further applied to three watersheds, Touchien river, Yenahui river and Kaoping river, as examples to state how to develop total mass control strategies. According to the case studies, a guideline to apply water quality models is established. The guideline describes required data and analysis procedure. Besides, characteristics of water quality models, analysis of simulation results, checklists of simulation, and detail descriptions of range of values of parameters are also included in appendixes. This study also extends last year’s results. The EIA reports of 2003 are added to the GIS database. The function of GIS database is enhanced, which provides functions to download input data files for QUAL2E and HSPF models and to run QUAL2E online. This study has complete input files for three study watersheds, more for other watersheds need future studies. The database also provides some tools to translate row data to input data for water quality models. This study tends to define standard procedure to prepare input data, calibrate parameters, run simulation models, and analysis of results to develop management standards for environmental impact assessment.

Water Quality Model,Total Mass Control,Geographic Information System