River and reservoir sediment characterization and assessment of environmental damages
The objectives of the project are to development and enhance the sediment transport model by applying the proper hydraulic and water quality models. For the purpose of compliance with relevant environmental regulations, the strategy and recommendation for the justified TMDL will be suggested based on the results of sediment modelling. The project first collected the background information of major reservoirs and rivers, current water body pollution condition and historical sediment monitoring results. According to the criteria of location, potential pollution, public water supply, and same water basin factors, Agongdian Reservoir, River and Estuary was selected as the project target waterbody to conduct the planning of supplementary investigation and enhance the water basin wide model calibration and verification. The scenario simulations were also modeled as the basis of follow-up management. Project supplementary investigation results indicated concentration of nickel and arsenic in Agongdian Reservoir sediment exceeded the lower limits of Sediment Quality Index, other heavy metals could meet the current regulatory limits. Since there is no pollution coming into the Reservoir, the arsenic is from natural background. Nickel was selected as the concerned pollutant to be modelled after considering of relevant calculation data, pollution control items of waterbody and sediment. It shows the simulation results of sediment transport model are all considered reliable and high-accuracy prediction. The monitoring results show the change of nickel concentration in sediment is not significant. The major reasons include the slow speed of water flow in reservoir and the effect of sediment transport is not significant. Concentration of Zinc and Chromium in Agongdian River sediment exceeded the upper limits of Sediment Quality Index, copper, nickel, arsenic, mercury, chlordane and DDT exceeded the lower limits of Sediment Quality Index. Considering the exception of River upper section, the concentration of sediment zinc in the reaming river section exceeded the upper limits of Sediment Quality Index. Zinc is set to be the target pollutant in the modelling. Sediment nickel concentration exceeded the lower limits of Sediment Quality Index, therefore nickel was also modeled. Scenario simulation results indicated that sediment dredging from GunYen Bridge (12.45km) to River mouth will reduce 65% of water basin pollution mass and sediment quality in entire river can meet the lower limits of Sediment Quality Index in the simulation period 5 years. Another major task in this project was to conduct 6 training workshops and 1 sediment sampling demonstration. Given sediment contamination is a new field in Taiwan, the promotion of revenant regulations, industry right and duties of the competent authority, promotion of remediation work right are all not implemented well. The course content included sediment law framework, example for sampling plan preparation, sediment investigation technologies, sediment management strategies and international remediation technologies introduction. After the workshop, the feedbacks could be the references for the future implementation of sediment regulations.
Transmission model, river, reservoir, estuary