A three-dimensional unstructured-grid hydrodynamic and water quality model (Semi-implicit Cross-scale Hydroscience Intergrated System Model-Integrated Compartment Model) is applied successfully for Chesapeake Bay. The model is validated with observations of salinity, chlorophyll-a, dissolved oxygen, nutrients, and phytoplankton productions from the year 1991 to 1995 for the mainstem and some major tributaries, based on multiple model skill scores. Model experiments are conducted to test the importance of having (1) an accurate representation of bathymetry to correctly predict hypoxia and other processes and (2) a high-resolution model grid for tributaries to correctly simulate water quality variables. Comparison with the model experiment results with bathymetry smoothing indicates that bathymetry smoothing, as commonly used for many systems, changes the stratification and lateral circulation pattern, resulting in more salt intrusion into shallow water regions, and an increase in the freshwater age. Consequently, a model with bathymetry smoothing can lead to an unrealistic prediction of the distribution of hypoxia and phytoplankton production. Local grid refinement shows significant improvement of model simulations on local stratification and water quality variables. Overall, the use of high-resolution unstructured grid model leads to a faithful representation of the complex geometry, and thus a seamless cross-scale capability for simulating water quality processes in the Bay including tributaries and tidal creeks.

中文翻译：

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使用非结构化网格模型对切萨皮克湾缺氧的数值研究：对水深测量表示的验证和敏感性

三维非结构化网格水动力和水质模型（半隐式跨尺度水科学集成系统模型-集成隔室模型）已成功应用于切萨皮克湾。该模型根据多个模型技能得分，通过 1991 年至 1995 年期间对干流和一些主要支流的盐度、叶绿素-a、溶解氧、营养物质和浮游植物产量的观察进行了验证。进行模型实验以测试具有 (1) 准确表示水深以正确预测缺氧和其他过程和 (2) 支流的高分辨率模型网格以正确模拟水质变量的重要性。与具有测深平滑的模型实验结果的比较表明，通常用于许多系统的测深平滑，改变了分层和横向环流模式，导致更多的盐侵入浅水区，并增加了淡水年龄。因此，具有测深平滑的模型可能导致对缺氧和浮游植物生产分布的不切实际的预测。局部网格细化显示模型模拟对局部分层和水质变量的显着改进。总的来说，使用高分辨率非结构化网格模型可以忠实地表示复杂的几何形状，从而可以无缝地跨尺度模拟海湾的水质过程，包括支流和潮汐小溪。具有测深平滑的模型可能导致对缺氧和浮游植物生产分布的不切实际的预测。局部网格细化显示模型模拟对局部分层和水质变量的显着改进。总的来说，使用高分辨率非结构化网格模型可以忠实地表示复杂的几何形状，从而可以无缝地跨尺度模拟海湾的水质过程，包括支流和潮汐小溪。具有测深平滑的模型可能导致对缺氧和浮游植物生产分布的不切实际的预测。局部网格细化显示模型模拟对局部分层和水质变量的显着改进。总的来说，使用高分辨率非结构化网格模型可以忠实地表示复杂的几何形状，从而可以无缝地跨尺度模拟海湾的水质过程，包括支流和潮汐小溪。