Linking Stream Network Process Models To Robust Data Management Systems

As a city grows and become denser, its river system also changes. The paved surfaces and efficient drainage systems in urban areas result in water moving quickly into the river network and less of it infiltrating into the ground. When these systems are inundated with a particularly intense storm, it can change both the flow regime of an urban river and its sediment regime (i.e., the quantity, size, and distribution of the river sediment being transported by the river). Most of us don’t notice the continuous changes to this dynamic system, but every once in a while, the degradation of a river network will result in the erosion of private property, the failure of a bridge, or the rupture of a trunk sewer. Municipal governments are already spending millions of dollars every year to combat river erosion and degradation, and climate change is making the problem worse.

In this project, researchers worked closely with partners in industry, municipal governments, and conservation authorities to a) advance scientific understanding of how changing river flows in urban areas affect channel erosion and stability, and b) develop decision support systems to improve the protection and restoration of natural assets in the urban environment. These were created by consolidating monitoring and modelling data from different disciplines and sources to make it useful to decision-makers in areas such as land use planning, risk assessment, climate adaptation, and stream rehabilitation.

The project developed or refined a number of new useful tools for urban water management:

1. Stream Power Index for Networks (SPIN) Tool

SPIN is an open-source tool that identifies areas within the urban river network that are susceptible to erosion. It does this by estimating the change in “stream power” (i.e. the rate of energy dissipation in a river) that has occurred as a result of urbanization.  This change is then used to model potential erosion in the river system. Researchers worked with Credit Valley Conservation (CVC) to incorporate the SPIN tool into the flood hazard decision support framework that was already being using to assess the economic impacts of erosion and flooding. With the addition of SPIN, this framework, called the Risk and Return on Investment Tool (RROIT), can quantify potential property and infrastructure damage costs under present and future climate conditions. It is currently being used to help decision-makers prepare emergency plans and prioritize capital investments. The Toronto Region Conservation (TRCA) is also using SPIN as part of their watershed planning process for the Etobicoke Creek Watershed Plan update and the Humber River watershed planning process. Updates of the model are ongoing to increase its flexibility and utility. SPIN is freely available to practitioners on Github: github.com/macvicab/SPIN

2. iEnvironment++ software platform 

iEnvironment is a software platform for integrated environmental monitoring and modeling of surface water. It is useful for researchers and practitioners alike who want to understand problems associated with surface water such as the impact of runoff on fish populations or on built infrastructure near a water course. Due to its usefulness, more and more organizations are using the platform, including researchers, nonprofit organizations, water management authorities, and conservation authorities.

3. Wobblestone

The Wobblestone is a new technology that uses RFID (Radio Frequency Identification) transponders to characterize the response of coarse sediment on the bed of a river to a flood event. This coarse sediment is important because its stability during high stress periods of flow will determine whether a riverbed will erode. The key innovation with the Wobblestone tracer is that even as it is bounced around by the water in the stream, the transponder always remains upright. The self-righting mechanism makes it easier to find the tracer between floods and estimate its depth, which improves prediction of whether it will move or not in subsequent floods. This information can help us develop better river dynamic models, and to support river restoration projects that can ultimately protect infrastructure and restore ecosystems.