Integrating river ecohydraulics in urban stormwater management

保护城市河流生态系统，同时提供进入河岸公园的机会，是加拿大许多城市为改善其公民生活质量而共同追求的目标。城市河流及其河岸是当地动植物群植物群的家园，为城市居民提供了绝佳的娱乐机会。人们很容易忘记，它们是市政排水系统的主要组成部分，因为它们在一种情况下排出雨水，而在另一种情况下则是实施雨水池的地点。虽然河岸上的植被在降低径流到达河流的速度方面发挥着重要作用，但雨水下水道网络是最大的加速器，与自然径流相比，雨水排放更快。这对河流水力学有直接影响，在暴雨期间，通过相对高速度的点排放，这往往会扰乱暴雨出口附近以及下游的河流生态系统。此外，雨水还携带着径流对城市景观的潜在污染物，可能对当地生态系统产生负面影响。城市河流的流态与自然河流中的流态在雨强谱的较低范围内差异最大。这也是最有可能在释放到受纳沃茨之前恢复适当水质和控制流速的范围。与降雨事件在东部魁北克平均每三天在夏季，一个综合的雨水管理系统，以保护生态系统沿着城市河流河段必须旨在提供适当范围的生态水力特性（速度和污染物负荷），以维持当地栖息地的生物多样性频繁的降雨事件。随着城市对河流的压力越来越大，传统解决方案的空间越来越小，成本增加，优化成为必要。

Preserving urban river ecosystems while providing access to riverbank parks is a goal shared by many Canadian municipalities for improving the quality of life of their citizens. Home to local fauna and flora, urban rivers and their riverbanks offer great recreational opportunities for city dwellers. It is easy to forget that they constitute a major part of the municipal drainage system, as they evacuate stormwater in one case, and are sites to implement stormwater ponds in the other. While vegetation on riverbanks plays an important role in decreasing velocities at which runoff reaches the river, the storm sewer network is the greatest accelerator, discharging stormwater more rapidly compared to natural runoff. This has a direct impact on river hydraulics through point discharges at relatively high velocities during rainstorms, which tend to disturb river ecosystems in the vicinity, as well as downstream, of the storm outlets. Furthermore, stormwater also carries potential contaminants from runoff on the urban landscape that can negatively impact the local ecosystems. The flow regime of urban rivers differs most from the regime in natural rivers in the lower range of the rainfall intensity spectrum. This is also the range that offers the best possibilities for restoring adequate water quality and controlling velocities before release into the receiving waters. With rainfall events in Eastern Quebec on average every three days in summertime, an integrated stormwater management system for preserving ecosystems along an urban river reach must aim at providing the proper range of eco-hydraulic characteristics (velocities and pollutant loads) to sustain the biodiversity in local habitats for frequent rainfall events. As urban pressure on streams goes stronger, there is less space for traditional solutions, costs increase, and optimization becomes a necessity.