Canal and Wetland Flow/Transport Interaction

Significant canal and wetland flow exchanges can potentially occur along the southwest overbank area of canal C-111 between hydraulic control structures S-18C and S-197. This coupled flow system is of particular concern to restoration efforts in that it provides a pathway for fresh water to nearshore embayments in Florida Bay. New construction modifications and operational strategies proposed for C-111 under the Central and Southern Florida "Restudy" Project are intended to enhance sheet flow to these subtidal embayments. The objectives of the canal and wetland flow/transport interaction project were to (1) develop numerical techniques and algorithms to facilitate the coupling of existing generic models for improved simulation of canal and wetland interactions, (2) translate recent findings of ongoing process studies within the South Florida Ecosystem Program (SFEP) into new mathematical formulations, empirical expressions, and numerical approximations to enhance generic simulation model capabilities for the south Florida ecosystem, (3) investigate new instrument capabilities and field deployment approaches to collect the refined data needed to identify and quantify the important flow-controlling forces and landscape features for model implementation, (4) integrate process-study findings and the results of physiographic mapping and remote sensing efforts specific to the C-111 basin into a numerical simulation model of the interconnected canal and wetland flow system, and (5) use the resultant model and data to study, evaluate, and demonstrate the significance of driving forces relative to controlling flow exchanges between canal C-111 and its bordering wetlands. Discharge data for Tamiami Canal are also available for water years 1986-1999, 2000, and 2001.

A complex network of canals, levees, and control structures, designed to control flooding and provide a continuous supply of fresh water for household and agricultural use, has altered naturally occurring flow patterns through the Everglades and into Florida Bay. Quantification of dynamic flow conditions within the south Florida ecosystem is vital to assessing implications of the residence time of water, potentially nutrient-enriched (with nitrates or phosphates) or contaminant-laden (with metals or pesticides), that can alter plant life and affect biological communities. Improved numerical techniques are needed not only to more accurately evaluate discrete forces governing flow in the canals and wetlands but also to analyze their complex interaction in order to facilitate coupled representation of transport processes. Flow and transport processes are integrally linked meaning that precise quantification of the fluid dynamics is required to accurately evaluate the transport of waterborne constituents. Robust models that employ highly accurate numerical methods to invoke coupled solution of the most appropriately formulated and representative equations governing flow and transport processes are needed. Through strategic use of a model, cause-and-effect relations between discharge sources, flow magnitudes, transport processes, and changes in vegetation and biota can be systematically investigated. The effects of driving forces on nutrient cycling and contaminant transport can then be quantified, evaluated, and more effectively factored into the development of remedial management plans. A well-developed model can be used to evaluate newly devised plans to improve freshwater deliveries to Florida Bay prior to implementation.

This project ended in 1999. Related work can be found at http://time.er.usgs.gov/.

For additional information about this project contact either:
Eric Swain, [e-mail], 954 377-5925 or Chris Langevin, [e-mail], 954 377-5917

在C-111号渠（canal C-111）西南岸带的水力控制构筑物（hydraulic control structures）S-18C与S-197之间，可能发生显著的渠系与湿地水流交换。该耦合水流系统是修复工作重点关注的对象，因为它为淡水输入佛罗里达湾（Florida Bay）的近岸海湾提供了通道。根据佛罗里达中南部"Restudy"项目提出的C-111号渠新建改造方案与运行策略，旨在强化向这些潮下海湾的片流输送。

本渠系与湿地水流/输移交互项目的目标如下：(1) 研发数值技术与算法，以实现现有通用模型的耦合，从而更精准地模拟渠系与湿地间的交互过程；(2) 将南佛罗里达生态系统项目（South Florida Ecosystem Program, SFEP）中当前开展的过程研究最新成果，转化为新的数学公式、经验表达式与数值近似方法，以提升南佛罗里达生态系统通用模拟模型的性能；(3) 探索新型仪器性能与野外部署方案，采集用于识别并量化模型实施所需的关键水流控制因子与景观特征的精细化数据；(4) 将针对C-111号渠流域的过程研究成果、地貌测绘（physiographic mapping）与遥感（remote sensing）工作结果，整合至互联渠系与湿地水流系统的数值模拟模型（numerical simulation model）中；(5) 利用最终构建的模型与数据，研究、评估并阐明驱动因子对C-111号渠与其毗邻湿地间水流交换的调控意义。

塔米亚米渠（Tamiami Canal）的流量数据涵盖1986-1999年、2000年及2001年的水文年（water years）数据。

这套由渠系、防洪堤与控制构筑物组成的复杂网络，旨在实现防洪与为生活、农业提供持续淡水供应，却改变了大沼泽地（Everglades）天然水流格局并影响其向佛罗里达湾的输运。对南佛罗里达生态系统内动态水流条件的量化分析，是评估水体停留时间（residence time）影响的核心前提——水体可能富含硝酸盐、磷酸盐等营养盐或携带金属、农药等污染物，进而改变植被并影响生物群落。

亟需改进的数值技术，不仅要更精准地评估渠系与湿地内水流的各离散控制因子，还要分析其复杂交互作用，以实现输移过程的耦合表征。水流与输移过程紧密耦合，这意味着需精准量化流体动力学特性，才能准确评估水载组分（waterborne constituents）的输移过程。需构建采用高精度数值方法的鲁棒模型（robust models），以对最适配且具代表性的水流与输移控制方程进行耦合求解。

通过合理运用模型，可系统研究流量源、水流强度、输移过程与植被及生物群落变化间的因果关系。由此可量化评估驱动因子对营养盐循环与污染物输移的影响，并将其更高效地纳入修复管理计划的制定过程。成熟的模型可在实施前，用于评估为提升佛罗里达湾淡水补给量而提出的新方案。

本项目于1999年结题，相关研究成果可访问网址http://time.er.usgs.gov/获取。

如需获取本项目更多信息，可联系以下人员：
埃里克·斯韦恩（Eric Swain），邮箱：[e-mail]，电话：954 377-5925；
或克里斯·兰格文（Chris Langevin），邮箱：[e-mail]，电话：954 377-5917