The purpose of this study is to assist Taiwan EPA in reviewing the report of environmental impact assessment (EIA) on the section of receiving water quality modeling. Four main tasks are conducted to provide technological support in examining the results of Water Quality Modeling which is used in the assessment of surface water quality. The tasks include: (a) reviewing at least 20 EIA reports, (b) providing comments on scoping meeting, (c) evaluating the performance of the four models (HSPF/BASINS, SWMM, WASP, and Qual2k) which were applied in EIA cases and summarizing the results of modeling application, and (d) holding a workshop to discuss Water Quality Modeling. In 2015, the water quality models (e.g. HSPF/BASINS, SWMM, WASP, Qual2k, and mass balance method) listed in the guidelines of Water Quality Modeling are used in project development as EIA report process. Seven EIA cases assessed by the complex models (HSPF/BASINS, WASP and Qual2k), 11 EIA cases by mass balance method, but 21 cases assessed by no model. Twenty-five EIA cases were followed up and comments were provided for 8 EIA cases during the scoping meeting.
The water quality models (HSPF/BASINS, SWMM, WASP, and Qual2k) are evaluated for their capability and applicability to the application of EIA cases. The results indicate that simulation of the four models can obtain comparable results under well fit of the process of calibration and confirmation. The parameters are summarized for future application. During this study, the parameters of the four models were collected based on EIA cases. For HSPF/BASINS, the parameters of the following rivers (Heping creek, Nanao creek, Jin Gua Liao, Diyu creek, Beishi River, Dahan River, Touqian River, and Fengshan creek) are collected. For SWMM, those of the following rivers (Feitsui, Touchien creek, Tachia River, and Dapumei creek) are collected. For QUAL2K, the following rivers (Xindian creek, Fengshan creek, Touchien creek, Danshui River, Dahan River, Heping creek, and Yanshui River) are collected. For WASP, the following rivers (Chishui creek, Danshui River, and Wu River) are collected.
Finally, several suggestions may help for further investigation. This study recommends that government agencies should work with institute to revise the modeling guidelines or implement models for EIA case applications. Moreover, the institute could play a critical role in archiving models and data, maintaining and upgrading them for future applications. The modeling workshops should take place frequently to emphasize on modeler education. Guidelines for model assessment should be further developed.