River dynamics and process-based restoration of fluvial systems

由于人类影响和全球环境变化，河流系统面临着相当大的压力。随着我们进入联合国生态系统恢复十年，人们越来越认识到，河流管理办法必须摆脱以形式为基础的恢复和将河流保持在固定位置的硬工程结构。该研究计划的长期目标是促进我们对河流动态和河流生态系统之间联系的理解，以支持可持续的、基于过程的河流恢复的发展。这种恢复包括为洪灾和侵蚀进程留下足够的运行空间，这在气候变化的背景下尤其关键，因为预计未来几十年流量的可变性将增加。这一长期目标将通过数值模拟与实验室和现场实验的结合和相互作用来实现。激光雷达高分辨率数字高程模型(DEM)的可用性增加，例如整个魁北克南部的数据现在可以免费获取，这也将极大地帮助实现这一目标。短期目标是：1)开发工具，帮助预测实施自由空间对未来河道演变的影响；2)评估在不同地貌背景下重新连接不同地貌背景下拉直的农业溪流中以前的曲流的影响；3)调查汇流带作为河流系统恢复的关键控制点的作用。这项研究计划的科学方法基于在不同地貌背景和一系列人为干扰，包括受沟道化、疏浚和堤岸加固影响的农业流域在内的几个河流河段的实地数据收集。现场测量包括详细的河床地形、速度、压力计监测、水位和流量，并将利用无人机图像分析工具。现场部分与舍布鲁克大学新的室外实验河流设施(OERF)进行的实验相结合。地理信息系统(GIS)对激光雷达数据的分析是我研究计划的核心部分，水文地貌工具旨在研究流动性和洪水过程，这些工具将进一步开发。汇流带将受到特别关注，以加深我们对这些带如何影响主河道物理非均质性的理解，并对支流和主河道密度差异(迄今)被低估的作用进行详细分析。该计划将在建立基于水文地貌学概念的河流管理专门知识以解决一系列河流的主要环境问题方面取得重大进展，并在开发地理信息系统和建模工具以更好地向河流管理者介绍基于可持续过程的恢复方法方面取得重大进展。

River systems are under considerable pressure due to human impacts and global environmental changes. As we enter the United Nations Decade on Ecosystem Restoration, it is increasingly recognized that river management approaches must move away from form-based restoration and hard-engineering structures that maintain rivers in a fixed position. The long-term objective of the research program is to advance our understanding of the links between river dynamics and river ecosystems to support the development of sustainable, process-based river restoration. Such restoration involves leaving sufficient space for flooding and erosion processes to operate, which is particularly critical in a context of climate change where increased variability in discharge is expected in the coming decades. This long-term objective will be reached through the combination of, and interactions between, numerical modelling and laboratory and field experimentation. The increased availability of LiDAR high-resolution digital elevation models (DEM), with for example data for the entire southern Quebec now freely accessible, will also greatly help in reaching this objective. The short-term objectives are to 1) develop tools to help predict effects of implementing a freedom space on future river channel evolution; 2) assess the impact of reconnecting former meanders in straightened agricultural streams in various geomorphological contexts and 3) investigate the role of confluence zones as key control points in fluvial system restoration. The scientific approach of this research program is based on the collection of field data at several river reaches in different geomorphological contexts and in a range of anthropogenic disturbances, including agricultural watersheds affected by channelization, dredging and bank stabilization. Field measurements include detailed bed topography, velocity, piezometer monitoring, stage and discharge, and will make use of drone imagery analysis tools. The field component is combined with experiments conducted at the new Outdoor Experimental River Facility (OERF) at Université de Sherbrooke. Geographical Information System (GIS) analysis of LiDAR data is a central part of my research program, with hydrogeomorphological tools designed to examine both mobility and flood processes that will be further developed. The confluence zones will receive particular attention to further our understanding on how these zones affect the physical heterogeneity of the main channel and to pursue detailed analysis on the (so far) underestimated role of density difference between the tributary and main channel. This program will allow significant progress in establishing an expertise in river management based on hydrogeomorphological concepts to tackle major environmental problems in a range of rivers, and on developing GIS and modelling tools to better inform river managers about sustainable process-based restoration approaches.