Erosion cost module to support flood risk analysis tool

河流和河流廊道是陆地和水生生态系统的重要组成部分，提供无数的生态系统服务，包括排水、向下游人口供水和减轻大洪水的影响。河网和洪泛平原经过数千年的发展，在山坡和上游集水区提供的沉积物数量与河流通过流体流动输送这些沉积物的能力之间趋于平衡。城市的发展使河流失去了平衡，因为沥青和混凝土限制了水的渗入，而房屋和道路上的排水沟加速了水向河道的输送。简单地说，河流还没有准备好承受这么多的水。侵蚀问题是地方性的，导致河流生态价值的退化，市政当局试图维护这么多公里日益不稳定的渠道，需要付出长期的代价。当前项目的目标是建立一个工具，使市政当局和其他利益相关者能够预测城市建设可能导致的侵蚀成本。雨水管理和低影响开发是试图管理这些问题的昂贵选择——但是什么都不做也是如此。相对较小的投资现在可以收回很多倍的成本，同时还有助于避免最具破坏性的生态发展影响。侵蚀工具将允许市政当局明确比较各种管理方案，以便在开发时更好地支持决策。＊＊＊＊

Rivers and river corridors are important components of terrestrial and aquatic ecosystems and provide innumerable ecosystem services that include draining the landscape, supplying water to downstream populations and mitigating the effects of large floods. River networks and floodplains develop over thousands of years and tend towards a balance between the amount of sediment supplied from the hillslopes and the upper catchment and the capacity of the river to transport that sediment by fluid flow. Rivers are thrown out of balance by the growth of cities because asphalt and concrete limit infiltration while the gutters on our houses and roads accelerate the delivery of water to river channels. Simply put, the rivers are not ready for so much water. Erosion problems are endemic, leading to degradation of the ecological value of the rivers and long term costs for municipalities trying to maintain so many kilometres of increasingly unstable channels. The objective of the current project is to build a tool that would allow municipalities and other stakeholders to anticipate the costs from erosion that may result from city building. Stormwater management and low impact development are expensive options to try to manage these issues - but so is doing nothing. Relatively minor investments now can pay for themselves many times over, all while helping to avoid the most damaging ecological impacts of development. The erosion tool will allow municipalities to explicitly compare various management scenarios in order to support better decision making at the time of development. ****