WAMSI 2 - Dredging Node - Theme 2 Project 3.4 Development of a Numerical Dredging Model

In Western Australia (WA), the Environmental Impact Assessment process requires dredging proponents to make scientifically sound predictions of the likely extent, severity, and persistence of environmental impacts of the proposed activity under a spatially defined zoning pattern. This is achieved by using coupled hydrodynamic, wave and sediment transport models in conjunction with water quality (ecological) thresholds for sensitive receptors such as corals, filter feeders, or seagrasses/macroalgae. These predictions guide the scale and scope of associated monitoring programs, providing assistance to proponents as to where to establish environmental monitoring and reference sites. Increasingly, modelling is also being used by dredging programs to forecast a few days in advance, so as to understand the potential consequence of various dredging scenarios and optimize the dredging programs to minimize environmental damage.\n\nThe overall objective of Project 2/3.4 was to improve the predictive capabilities of sediment dispersion modelling that incorporate dynamic plume and passive plume processes through assessing model sensitivity to key forcing and parameter values, such as met-ocean condition, particle settling velocity distribution, critical shear stress, sediment erosion and deposition, provide frequency and duration of biological stressor fields including suspended sediment concentration, sediment accretion and erosion, and available light; and provide guidance on developing best practice algorithms and parametrizations for dredge plume modelling.\n\nBased on the outcome Project 2/3.1, an appropriate modelling suite that includes hydrodynamics, waves, and sediment transport was chosen (Delft3D) to model the far-field passive plume. The model was set up and validated using the bathymetry and baseline data collected as part of the Chevron Australia Wheatstone Project, located near Onslow, Western Australia.\n\nThe model outputs were assessed against monitoring data from Chevron Australia's Wheatstone Dredging program, including, remote sensing and in-situ data collected in Project 2/3.2. A 20 month hindcast of passive plume dispersal from the dredging project to the furthest extent of the passive plume were compared with the field data and MODIS images (where available). Spatial and temporal variability of plume dispersal under different forcing scenarios and sediment release rates were investigated and reported.\n\nThis record pertains to the simulation data files. \nLineage: Three models (hydrodynamic, wave and sediment transport models) were set-up for the study site, Chevron Australia's Wheatstone LNG Project, located 12 km west of Onslow (in the Pilbara region of Western Australia). Data from a range of sources were compiled and analysed for use in the study and included electronic and daily dredging logs, current meters, Conductivity Temperature Depth (CTD) measurements, turbidity (NTU) sensors, photosynthetically active radiation (PAR) sensors, sediment traps and multi-beam bathymetric survey data. Data from a field trip completed by CSIRO and Curtain University was also utilised. \n\nA 14-year-long derived TSS dataset for the Pilbara region using Moderate resolution Imaging Spectroradiometer (MODIS) satellite was developed in Dorji et al. (2016). \n\n. A description of the model set-up and results, including details of the sensitivity analysis (and validation of source terms) is included in the Final Report (see online resources link).\n\nTwo model output data files are provided in the CSIRO DAP record (see online resources link): \n\nFILE 1 Timeseries output at 14 minute intervals for 256 history points across the model domain (trih-gD1_DSN_Outer.nc)\nFILE 2 Map series output at 60 minute intervals for the model domain (trim-gD1_DSN_Outer.nc)\n\nVariable descriptions and units are provided in the file metadata. Example outputs include wave height, peak wave period, suspended solids concentration, water currents, water levels, bed shear stress etc. Simulation data files are in netCDF format with CF-1.6 conventions.\n

在西澳大利亚州（Western Australia, WA），环境影响评估流程要求疏浚项目方针对划定的空间分区模式，科学合理地预测拟建活动可能产生的环境影响范围、严重程度及持续时长。该预测需通过耦合水动力、波浪与泥沙输运模型，并结合珊瑚、滤食生物、海草/大型藻类等敏感受体的水质（生态）阈值实现。此类预测将指导相关监测计划的规模与范畴，协助项目方确定环境监测与对照点位的布设位置。如今，疏浚项目也愈发普遍地借助模型开展数天的提前预报，以研判不同疏浚场景的潜在影响，优化疏浚方案以最大限度降低环境损害。

项目2/3.4的总体目标，是通过评估模型对关键强迫力与参数值（如海洋气象条件、颗粒沉降速度分布、临界剪切应力、泥沙侵蚀与沉积过程）的敏感性，改进纳入动态羽流与被动羽流过程的泥沙扩散模拟能力；同时提供包含悬浮泥沙浓度、泥沙淤积与侵蚀、有效光照在内的生物胁迫场的频率与时长分布，并为疏浚羽流模拟的最佳实践算法与参数化方案提供指导。

基于项目2/3.1的研究成果，本次研究选取了包含水动力、波浪及泥沙输运模块的适宜模型套件Delft3D，用于远场被动羽流的模拟。模型通过采集自西澳大利亚昂斯洛附近的雪佛龙澳大利亚（Chevron Australia）惠斯通项目的水深地形与基线数据完成搭建与验证。

研究将模型输出与雪佛龙澳大利亚惠斯通疏浚项目的监测数据进行比对，包括项目2/3.2中采集的遥感与原位监测数据。将该疏浚项目被动羽流扩散长达20个月的后报结果，与实地观测数据及中分辨率成像光谱仪（Moderate resolution Imaging Spectroradiometer, MODIS）影像（如有）进行对比；同时分析并报告了不同强迫场景与泥沙释放速率下，羽流扩散的时空变化特征。

本数据集对应模拟数据文件。
数据谱系：针对位于西澳大利亚州皮尔巴拉（Pilbara）地区昂斯洛以西12公里处的雪佛龙澳大利亚惠斯通液化天然气（LNG）项目研究场地，搭建了三类模型：水动力模型、波浪模型与泥沙输运模型。研究中整合并分析了多源数据，包括电子日志与每日疏浚日志、海流计数据、温盐深（Conductivity Temperature Depth, CTD）测量数据、浊度（NTU）传感器数据、光合有效辐射（Photosynthetically Active Radiation, PAR）传感器数据、沉积物捕集器数据与多波束水深地形测量数据。同时还使用了澳大利亚联邦科学与工业研究组织（Commonwealth Scientific and Industrial Research Organisation, CSIRO）与科廷大学（Curtin University）联合开展的野外考察数据。

Dorji等人（2016）利用MODIS卫星数据，生成了皮尔巴拉地区长达14年的总悬浮泥沙（Total Suspended Solids, TSS）数据集。

模型搭建与结果的详细说明，包括敏感性分析（及源项验证）内容已收录于最终报告（详见在线资源链接）。

本CSIRO数据存档计划（DAP）记录中提供了两个模型输出数据文件（详见在线资源链接）：
文件1：模型全域内256个历史点的14分钟间隔时序输出文件（trih-gD1_DSN_Outer.nc）
文件2：模型全域60分钟间隔的序列制图输出文件（trim-gD1_DSN_Outer.nc）

变量说明与单位详见文件元数据。示例输出变量包括波高、峰值波周期、悬浮固体浓度、海流、水位、床面剪切应力等。模拟数据文件采用符合CF-1.6规范的netCDF格式存储。