The purpose of this study is to assist Taiwan EPA in reviewing the report of environmental impact assessment (EIA) on the section of 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 the surface water quality. The tasks include: (a) reviewing at least 20 EIA reports, (b) assessing the applicability and limitations of the water quality models on the heavy metal and the simulation of emerging contaminants, (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 the water quality modeling. The study has adopted the water quality models (e.g. HSPF/BASINS, QUAL2K, and Mass Balance Method) listed in the guidelines of the water quality modeling to evaluate twenty EIA cases during this study. Five of them were assessed by the complex models (HSPF/BASINS and QUAL2K), seven by the Mass Balance Method, but eight were not assessed by any models. Fifteen EIA cases were followed up, and comments of the two EIA case were provided 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 the EIA cases. The results indicate that the HSPF/BASINS, SWMM, and WASP can be applied to heavy metal simulation and obtaining comparable results under well fit of the process of calibration and confirmation. However, the models can not be empolyed in the simulation of emerging contaminants in the EIA cases. The parameters of the four models are summarized for future application. During this study, the parameters of the two models were collected based on the EIA cases. For the HSPF/BASINS, the parameters of the Feng-shan Creek are collected. For the QUAL2K, the Cian-hua Creek, Da-an River, and Hsin-Jie Creek are collected.
Finally, several suggestions for further investigation are provided. This study recommends that government agencies should work with institute to revise the modeling guidelines or model implementation for applications in EIA cases. Moreover, the co-working institute can 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.