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

该项目将提高我们保护城市河流基础设施和生态健康的能力，这些河流由于流量变化而变得不稳定。在城市地区，地表的变化（加上雨水渠的建设）从根本上改变了水在地表的流动方式。在城市地区，同样的暴雨会产生比自然环境中更大的洪水，而城市河流由于流量的增加而变得不稳定。为了控制与城市河流相关的危害，通常的做法是在河流内设计和建造一系列结构，以限制污染，特别是当道路、建筑物或埋地管道等基础设施可能受到影响时。过去的做法依赖于建造大型岩石特征和/或混凝土结构，旨在防止任何流动的流在所有（所谓的“硬工程”技术），也就是说，流被从一个不可接受的不稳定状态，导致城市化到一个完全静态的一个没有改变的渠道是可能的。自然的、稳定的状态（每年都会发生小的、局部的变化）被完全忽略了，结果，依赖这些河流的生态系统受到了影响。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河道稳定性的因素方面取得的进展表明，通过添加或去除河流中天然存在的少量粗颗粒物质，可以逐渐调整河道活动的水平。这意味着，与其迫使河流在混凝土边界的范围内保持完全静止，还不如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，这种不稳定可能代价高昂，无论是在损害还是在人命损失方面。这笔赠款将允许GEOMorphix有限公司和UBC在大多伦多地区正在进行的恢复活动的背景下评估这种有前途的方法。

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.