Trajectory Analysis of Inland Water Discharges into the Santos Estuarine System

ABSTRACT In order to optimize action strategies for environmental management plans and environmental projects in coastal areas, the investigation of processes related to an estuarine system contributes to a better inference of the complex dynamics of constituents present in its water. This paper reports a hydrodynamic study of the Santos Estuarine System (São Paulo State, Brazil) focused on aspects related to the transport of constituents from inland water discharges. A computational model was implemented using SisBaHiA (Base System for Environmental Hydrodynamics) in order to reproduce the hydrodynamic patterns of the system. Based on the Lagrangian Transport Model the most significant tributary river discharges were represented: Boturoca River, Cubatão River, Quilombo River and Itapanhaú River. Results were probabilistically analyzed based on the lifetime of tributary discharges flowing into the estuarine system and their position during the simulation period. Such simulation results were presented on contour maps of occurrence percentage separated by lifetime limits, supporting a trajectory analysis of the inland water discharges. Map results indicated that water from Cubatão River reaches the Santos Bay preferably through the mouth of the São Vicente Estuary and water from Quilombo River preferably flows through the Port of Santos Channel instead. Water from Cubatão River remained in a mangrove area during most of the simulation period. Considering 3 days of lifetime limit only 1% reached the main channels.

摘要 为优化沿海区域环境管理规划与环境工程的行动策略，开展河口系统相关过程研究，有助于更精准地推断其水体中各类组分的复杂动力学特性。本研究针对巴西圣保罗州桑托斯河口系统（Santos Estuarine System）开展水动力学研究，重点关注内陆径流携带组分的输运过程。本研究采用SisBaHiA（环境水动力学基础系统，Base System for Environmental Hydrodynamics）搭建计算模型，以复现该系统的水动力格局。基于拉格朗日输运模型（Lagrangian Transport Model），本研究表征了四条主要支流的径流过程：博图罗卡河（Boturoca River）、库巴唐河（Cubatão River）、基隆博河（Quilombo River）以及伊塔潘哈乌河（Itapanhaú River）。基于模拟时段内汇入河口系统的径流存活时长及其空间位置，对模拟结果开展概率性分析。上述模拟结果以按存活时长阈值划分的出现百分比等值线图形式呈现，可为内陆径流的输运轨迹分析提供支撑。地图分析结果显示，库巴唐河的水体优先通过圣维森特河口汇入桑托斯湾，而基隆博河的水体则更倾向于经由桑托斯港航道输运。库巴唐河的水体在大部分模拟时段内滞留于红树林区域。若以3天为存活时长阈值，仅1%的水体能够抵达主航道。