River restoration revolution: evaluation of new, low impact channel designs using physical models

该项目将提高我们保护因水流变化而变得不稳定的城市溪流的基础设施和生态健康的能力。在城市地区，地表的变化(与雨水渠的建设相结合)从根本上改变了水在地表上流动的方式。与自然环境相比，城市地区的暴雨会产生更大的洪水，由于流量增加，城市溪流变得不稳定。为了控制与城市溪流相关的危险，通常的做法是在溪流内设计和建造一系列建筑物，以限制河流的活动，特别是在道路、建筑物或地下管道等基础设施可能受到影响的情况下。牧场实践依赖于建造大型岩石和/或混凝土结构，旨在完全防止溪流的任何移动(所谓的“硬工程”技术)；即溪流从城市化导致的不可接受的不稳定状态转变为完全静止的状态，不可能改变隧道。自然的、稳定的状态(每年发生小的、局部的变化)完全被绕过，结果，依赖这些溪流的生态系统受到影响。最近，政策制定者和土地管理者表达了保护基础设施和水生生态系统的意图。伊顿博士和他的研究小组在控制渠道稳定性因素方面取得的进展表明，通过添加或移除少量自然存在于溪流中的最粗物质，可以逐步调整渠道活动的水平。这意味着，不是强迫河流在混凝土边界内保持完全静止，而是有可能改变河道内的沉积物，以恢复河道活动的自然水平，并防止城市化引起的不稳定，这可能会造成损害和人员伤亡的代价高昂。这笔赠款将使GEOMorphix有限公司和UBC能够在大多伦多地区正在进行的修复活动的背景下评估这一有希望的方法。

This project will improve our ability to protect infrastructure and ecological health for urban streams that havebecome unstable due to flow changes. In urban areas, changes to the land surface (combined with theconstruction of storm drains) has fundamentally altered how water moves across the land surface. The samerainstorm in a urban area produces a larger flood than it would in a natural environment, and urban streamsoften become unstable due to the increased flows. In order to control the hazards associated with urbanstreams, it is common practice to design and build a range of structures within the stream in order to limiterosion, particularly when infrastructure such as roads, buildings or buried pipes could be affected. Pastpractices relied on building large rock features and/or concrete structures designed to prevent any movement ofthe stream at all (so-called 'hard engineering" techniques); that is, streams were transformed from anunacceptably unstable state resulting from urbanization to a completely static one where no change to thechannel is possible. The natural, stable state (in which small, localized changes occur on an annual basis) iscompletely by-passed, and as a result, the ecosystems that depend upon these streams suffer. Relativelyrecently, policy makers and land managers have expressed their intention to protect both infrastructure andaquatic ecosystems. The advances made by Dr. Eaton and his research group on the factors controlling channelstability suggest that it is possible to gradually adjust the level of channel activity by adding or removing smallvolumes of the coarsest material naturally found in the stream. This implies that, rather than forcing a stream toremain completely static within the confines of a concrete boundary, it may be possible to modify the sedimentwithin the channel so as to restore the natural level of channel activity, and to prevent the urbanization-inducedinstability that can be costly, both in terms of damage and loss of human life. This grant will allow GEOMorphix Ltd. and UBC to evaluate this promising approach in the context of ongoing restoration activities inthe Greater Toronto Area.