Application for contaminated sediment transport modeling in a river and reservoir
The main focus of the project is the development of a transmission model framework, which was then used to evaluate a range of sediment restoration scenarios for the select river system and target reservoir. The assessment outcome was then incorporated into the management strategies and recommendations for the sediment clean-up effort. The project work started with data and information gathering and field program development for collecting hydrographic data of the river system and target reservoir. The water quality modeling framework, WASP was adopted as the platform for developing the fate and transport model of the Dahan River in Taipei, selected as the target river system, CE-QUAL-W2 was another one adopted as the platform for developing the transmission model of the Shimen Reservoir in Taoyuan, selected as the target reservoir. Results of Shimen Reservoir from the field program revealed that water and sediment were below the regulatory value, and not found pollution behavior around the reservoir, we take copper for example, define seven different scenario to predict pollution situation. Its results show that the upstream input copper takes up 51,840 kg / day or more, and discharge continuously, sediment quality at Shimen Dam area would exceed the lower limit. Currently, administration agency should continuously monitor water and sediment quality, avoid sporadic or accidental pollution discharge events. Results of Dahan River from the field program revealed that existing levels of copper, zinc, and nickel in the Dahan River sediments exceed the water quality criteria with copper the metal most frequently violating the standard. The river portion between the Fu-Chou Bridge and Xinhai Bridge is still found having the highest metal concentrations in the sediment as a result of the significant metal loads from sources in the watershed. The WASP model simulation results indicated that metal levels in the Dahan River sediments will continue to rise if no actions were taken to reduce the metal input. On-site removal of the contaminated sediments would only be a temporary measure to lower the metal contents in the sediment if the external inputs are not curbed. High pollution loading of the Tahan river pollution contained Nanzaigou ditch, Taliaokeng river etc., they already has sewage interceptor system. So administrator could reduce loading by operating the system in short term. To improve the pollution situation in the whole basin, pollution’s TMDLs (total maximum daily loadings) could be considered to action in the future. If removing contaminated sediments along with control of the external inputs, it would be the preferred strategy to gradually restore the river sediment system to within the metal thresholds in long time. In addition, important river situation such as typhoons or rainstorms, could cause upstream sediment erosion, so we observe sediment transport and redistribution in this program. Another key point of this project is to conduct a training workshop, it was held on October 17 and 18 in 2013, the course content include sediment law framework, administrative procedures of sediment quality recording, example for sampling proposal, sample analysis technologies, sediment management strategies and remediation technologies introduction. After the workshop, one propose sediment quality regulatory adjustment suggestions according the workshop feedback and consolidate domestic and international sediment regulations.