Wilket Creek: urbanization, geomorphology, policy, and design

The understanding of the morphology of an urbanized channel is currently limited to a ‘black box’ understanding in that the main driving force of morphological change is hydrologic. This study aimed to expand our understanding of urbanized channels by conducting a socio-geomorphological investigation; that is, the natural and policy-driven events and processes leading to the current channel form. A fluvial audit including historical analysis and fieldwork was conducted in Wilket Creek, a southern Ontario urbanized channel, along with a review of provincial and municipal policy and reports. Overall, it was concluded that the current morphology of Wilket Creek is the result of a complex combination of urbanization, conservation policy, and channel reconstruction and design. This in-depth analysis provides the sequence of events and processes which took place in the catchment which has led to the current urban morphology

A Sediment Budget of an Urban Creek in Toronto

Wilket Creek is a second order stream located in Toronto, Ontario. Over the past decade, management efforts have intensified to protect infrastructure including walking paths, bridges, sanitary sewers and private property. As a result, the City of Toronto and the Toronto and Region Conservation Authority have undertaken projects to protect infrastructure by re-aligning the creek and hardening banks. Many of the projects have not been successful over the long term and efforts to protect infrastructure are ongoing. The goal of this research project has been to understand how sediment moves through Wilket Creek. This was accomplished by conducting a sediment budget which is an account of sediment inputs, outputs and storage in a fluvial or geomorphic system. Initially a morphological approach was employed to estimate volumetric sediment transport. The results contributed to a comprehensive sediment budget which assessed relative sediment input, output and storage components. As part of the study, efforts were undertaken to establish Wilket Creek as a long term field monitoring site for research on urbanization and sediment transport. Fieldwork was carried out over a two year period to assess input, output and storage terms of the sediment budget and estimate sediment transport. A comprehensive sediment budget identified bank erosion in the middle and lower reaches as the primary sediment inputs. A dam and bank storage in the lower area of the watershed were the main storage terms. Sediment outputs included the confluence with the West Don River, bank storage near the confluence and dredging behind a dam. Sediment transport calculations estimated that sediment output at the confluence was between 680 and 1,300 ton/yr/km2. Based on field measurements and observations, isolated locations of channel instability were identified in the middle reaches while a more general trend of channel adjustment was observed in the lower reaches upstream of the West Don River. Further research should concentrate on obtaining reliable discharge measurements, refining estimations of sediment budget terms and conducting additional analysis of historical aerial imagery. Finally, additional study should be undertaken to identify the causes of channel adjustment prior to initiating new restoration efforts

Bedload sediment transport regimes of urban gravel-bed rivers under different management scenarios

Watershed urbanization profoundly alters the hydrologic characteristics of urban rivers compared to their rural counterparts. This change in hydrologic conditions in combination with alterations to the sediment supply regime in urban watersheds leads to adjustments to channel form and the widespread degradation of urban rivers. Urban river management increasingly attempts to balance the societal needs of flood and erosion control, while simultaneously improving the ecological health or waterways. Two common types of river management include stormwater management (SWM), which focuses on the attenuation of urban floods, and in-stream restoration, which attempts to reconstruct stable and ecologically favourable channels. However, current urban river management designs lack consideration of the key process responsible for channel stability and habitat availability: bedload sediment transport. Two reasons for this shortcoming are the lack of bedload sediment data in urban watersheds and the consequent gap in understanding of the bedload transport dynamics of urban rivers. Consequently, the degradation of urban rivers persists. This project investigates bedload transport dynamics in urban rivers with different management scenarios to focus on four themes: (1) how urbanization affects bedload transport dynamics and its relationship to channel morphology, (2) how to best predict bedload transport dynamics in urban rivers, (3) how current urban river management strategies change the transport dynamics of rivers, and (4) how to improve bedload sediment monitoring technology. This project focuses on the grain-scale bedload transport dynamics of coarse material because it links to the morphodynamics and ecological processes of channels, it provides insights on the exact controls and spatial variability of bedload transport, and the responses to individual flood events can be directly measured. The overarching goal of this study is to contribute to improved urban river management strategies that focus on adaptive management and interdisciplinary approaches. Bedload sediment transport was monitored using RFID tracer stones in three streams with different hydrologic settings: rural, urban with no SWM, and urban with SWM. High-resolution water level data confirmed the hydrologic differences expected from the three watershed conditions, as well as channel enlargement characteristic of urban rivers. Results demonstrate that the morphologic differences between the study streams can be linked to changes in the grain-scale bedload transport dynamics of the streams. Bedload transport is accelerated in the urban stream due to an increase in the frequency of bedload mobilization, particularly of coarse sediment sizes. In contrast, SWM hasdecreased the bedload transport to an immobile and armoured state indicative of a competence-limit transport regime. Results are used to make recommendations for improved urban river management. Results from the bedload tracking were used to build predictive models of tracer displacements. A new variable that captures both the mobility and travel length of bed particles is introduced. Several flow metrics developed in the literature in rural and laboratory settings are calculated, and their ability to predict tracer displacements in the three streams is tested. Scaling tracer travel lengths by mean channel width collapses the data into a single, strong relationship with cumulative energy expenditure, providing a single model that can be used across systems with different watershed conditions. To assess the impact of an in-stream riffle-pool channel reconstruction on bedload sediment dynamics, bedload transport and morphologic change was monitored in adjacent unrestored and restored reaches of an urban channel. Results reveal that the restored reach is stable and self- maintaining, mirroring bedform maintenance processes in natural riffle-pool streams. However, the construction is more successful at slowing down the transport of coarse sediment more than fine sediment, leading to a coarse sediment discontinuity that may be contributing to accelerated channel adjustment beyond the limits of the constructed riffle-pool sequences. This project highlights the importance of considering the entire channel corridor when designing and monitoring restoration projects. A large limitation of bedload sediment tracking technology is the inability to determine the vertical position of tracers, which hinders the ability to study vertical mixing and translate tracer data into bedload transport rates. A new Radio Frequency Identification (RFID) bedload tracer stone is presented, along with results of laboratory performance tests. This new bedload tracer improves upon existing bedload sediment monitoring technology by providing the ability to measure the burial depth of tracers without disturbing the bed. An important contribution of this study is the extensive dataset of bedload transport collected in urban rivers. This study attempts to move away from descriptive differences in the characteristics of urban rivers compared to rural streams, and towards a process-level understanding of the anthropogenic effects on river systems. Grain-scale bedload transport theory, developed in rural and laboratory settings, is applied to urban settings to gain insights into the effects of urbanization and common river management strategies on the geomorphic processes of urban rivers. Recommendations for improved urban river management are developed from the results of this thesis

A Review of Watershed Restoration Practices and Partnerships in the Toronto region

With the continued urbanization of cities through the Great Lakes Basin, the continued degradation of these areas will occur without substantial efforts to restore the natural environment. The research in this paper explores the sustainability of the watershed restoration project implemented in the Toronto region of Ontario Canada. It is assessed through the use of four indicators: Land and Water Acquisition, Adaptive Management, Funding Process, and Public Participation and Community development. The lessons learned through the research, interviews, and analysis of four watershed restoration case studies in the Toronto region help to inform and improve on the methods and tools used for watershed restoration projects across the Great Lake Basin. The normative UPE framework used to assess the sustainability of watershed restoration projects uncovered some significant issues in the entire watershed management framework. This combined with pragmatic methods and tools like adaptive management, provides insights and information concerning the intricate relationship between watershed restoration and the social, political and economic sphere. The recommendations for future watershed restoration work include enacting a streamlined watershed restoration communication centre, a standardizing an adaptive management framework through consistent funding tactics, and implementing innovative public engagement tools. This is all to help advance the sustainability of the watershed restoration projects, and the overall health and sustainability of the Toronto region watersheds. This might ultimately shift us from an era of watershed degradation in the Toronto region to an era of watershed restoration and help mitigate the impacts from urbanization through sustainable watershed restoration projects

A river's connective tissue: Lab observations of particle pathways and riffle formation during floods

In rivers it is difficult to quantify bedform dynamics during storm events. Direct observation of sediment pathways would provide insight into the mechanisms that underly bedform formation and destruction. In the current study, our objective was to visualize these processes in a meandering pool riffle system with partial bed cover. Observing erosive and depositional patterns, as well as the locations of active sediment transport, provides insight into the validity of various pool-riffle maintenance theories. We used a physical 1:40 scaled model of Toronto’s Wilket Creek to simulate storm events during which riffles formed as connective bedforms between alternate point bars. Exported sediment was weighed and sieved to measure the grain size distribution, while the bed’s pre- and post- storm topography was quantified using Structure-from-Motion techniques. Sediment pathways were observed using a novel technique, where regions of interest were filmed at 60 frames per second under ultra violet light, illuminating painted tracers. Three paint colors were used for different size tracers, which allowed us to apply image segmentation and create separate videos for three size fractions of the sediment. Pathways were then extracted using Lagrangian tracking software. Results show that the area of active transport is limited to a narrow portion of the channel width that increases with flood stage. At low flow, transport is routed along the toe of point bars, while no particles travel into the region of the pool, where the bed is uncovered. Riffles are rarely observed at these stages. As the flow increases, the lateral extent of active transport expands to include the higher parts of the bars, while connective riffles grow in areal extent and height. Erosion and deposition was found to occur more readily along the active sediment transport zones. Pathways varied by particle size so that smaller particles traveled higher over the point bar and large particles tended to collect in the riffle. These results indicate that sediment-routing is a dominant mechanism behind the formation and maintenance of riffles in meandering rivers. Future work to quantify these processes will increase the effectiveness and longevity of river remediation design through targeted sediment augmentation instead of bedform reconstruction

Dreams of Slaughter

A descent into the ravine is a step through a tear in urbanity. The terrain vague is a foil to the capitalist city; against a demand for order, specificity, and integration, it is disorienting, banal, erratic. Operating outside the constraints of dominant social structures, it harbours the unconscious of the city, not only an inevitable, but also a necessary rupture in the urban fabric. In this subterranean realm, the striated and measured plots of land are sporadically smoothed over by persistent nature, reclaiming its territory. These perceived voids invite projections of desire, both at a civic scale and on an individual level, that consequently shape the space. These are grounds of negotiation, a political realm often driven more by visceral impulses than economics. They aggravate tensions typically suppressed in the city, including those wrought by violence and melancholy. This is a portrait of the Don Valley in Toronto. Fragments of representation reveal the role of this space in the collective memory of the public. Beyond the infrastructure that binds them, the city and the valley are integrated through their opposition: one fuels the experience of the other

Gathering Abundance: An Exploration of Urban Foraging Practices in Toronto

This paper explores different urban foraging practices within Toronto aiming to understand the motivations for foraging within an urban centre, how this is enacted, and how the context of Toronto affects this practice. As an emerging field of study, there are few articles directly about urban foraging, but a wide body of literature which informs the topic. Seventeen semi-structured interviews were conducted, two with land managers, three with land managers/foragers, and twelve with foragers while walking through greenspaces in Toronto. The themes that emerged from the interviews were those of forager identity, environmental stewardship, (re)connection from nature, and private property, laws and transgression. Through foraging practices in the city people are able to interact with public greenspaces, and become participants within ecological and social communities. Eating weedy species and distinctions between native and introduced species heavily influence foraging practice. The embodied process of this work through harvesting and utilizing the plant materials creates a strong sense of connection to local seasonal cycles and food systems. Decisions to transgress bylaws are grounded in different notions of the role of nature and public spaces in the city. There is the potential for foraging practices to be part of sustainable and dynamic urban ecologies

Design of a Remote, Integrated, Automatic and Continuous Bedload Sediment Transport Monitoring Station and Application in a Rural Stream in Southern Ontario

The form and function of a stream network is directly influenced by natural processes and human activities that occur within the watershed. Human modifications in the form of urban and agricultural development alter natural water and nutrient cycles, which adversely affects stream health and stability. As new stormwater management techniques that aim to mitigate these impacts become more commonly implemented, it is prudent to investigate if we can continue modifying the landscape and alternatively realize a net benefit to stream health and stability. To evaluate the effectiveness of stream restoration efforts, baseline flow and bedload sediment transport characteristics should be characterized. However, many commonly used bedload monitoring methods often yield limited inter-flood or discontinuous data, which restricts our understanding of bedload transport dynamics. Field efforts involved in collecting these data can be difficult, expensive, and dangerous in some circumstances of significant flow. This thesis presents a new remote, integrated, automatic and continuous bedload monitoring station. The station configuration is relatively inexpensive, easy to deploy in the field, and designed for remote applications. The station was deployed at a semi-alluvial headwater creek located in an agricultural watershed in Southern Ontario where baseline flow and bedload sediment transport characteristics were studied. The station integrates two indirect monitoring devices including an in-situ radio frequency identification (RFID) antenna tracker and “Benson-Type” seismic impact plates. 400 synthetic RFID tracer stones divided into four size classes were seeded upstream of the station to be tracked automatically as they gradually pass over the in-situ RFID antenna. The “Benson-Type” seismic impact plates rest along the creek bed surface and function by converting mechanical energy exerted by mobile bedload particles that strike the plates into electrical energy recorded as total counts. A sediment trap was installed to help calibrate the continuous impact plate data record. Supplemental inter-flood tracer tracking surveys were completed to monitor tracer movement along the study reach. Field observations were used to build a predictive model of bedload sediment transport. The predictive model was used in combination with hydrologic model outputs to make relative comparisons of tracer displacement under alternative land-use scenarios. The field study was limited by technical shortcomings that ultimately prevented consistent operation of the station during the study period and uncertainty in impact plate device performance limited the usefulness of the recorded dataset. Technical improvements were gradually added to the bedload monitoring station throughout the study period and additional planned upgrades should allow for more consistent operation in the future. It is recommended that the impact plates undergo flume experimentation in a future study to clarify uncertainties related to device performance

The Mad and the Bad: The Lethal Use of Force against Mad People by Toronto Police

Since the killing of Edmond Yu by Toronto Police 16 years ago, police use of force incidents against Mad people in Toronto have resulted in nine additional deaths. This article investigates and analyzes the circumstances of the people who have been killed by Toronto police officers while experiencing mental distress. Reading the cases together reveals a pattern of intersecting sanist and racist discrimination, with racialized mad people being perceived by police officers as dangerous and deviant for who they are, rather than what they have done. Further, a link exists between police behaviour and judicial acceptance of that conduct. Police engage in sanist and racist profiling because the agencies overseeing their actions, as well as the courts, allow it. I argue that the Special Investigations Unit (SIU), which is supposed to be a civilian-led and independent agency, actually serves as an extension of the police force, providing only an illusion of accountability. Keywords: Mad people; racialization; criminalization; Toronto police; accountability Depuis le meurtre d’Edmond Yu il y a 16 ans, la force excessive et mortelle utilisée par la police de Toronto n’a pas diminuée, ayant comme résultat les morts de neuf autres personnes psychiatrisées. À travers l’analyse de ces meurtres, nous réaliserons que les identités construites aux intersections d’un processus de racialisation négatives et des questions de santé mentale sont perçues comme dangereuses, et comme déviantes, en tant que telles, et non pour leurs actes, ce qui mène à l’utilisation d’une force excessive et mortelle par les officiers de police. Mots-clés: personnes psychiatrisées; processus de racialisation; criminalisation; police Torontoise; responsabilite

Placemaking for the pedestrian: generative design & the street

This paper evaluates the influence of placemaking design concepts and historical development processes on the pedestrian experience of three different neighbourhood commercial streets in Toronto. Placemaking is an urban design movement that proposes walkable, pedestrian-­‐oriented environments in reaction to Modern planning's "placeless" car-­‐dominated landscapes. To explore if placemaking design theories relate to actual pedestrian experiences, I conducted qualitative case studies of three Toronto streets using spatial analyses, interviews, photographic observation, and archival research. I found that placemaking design concepts did correlate to positive pedestrian experiences, but the theories were lacking when it came to explaining pedestrian accounts of the age and storied character of the street. This led me to investigate the historic formation and evolution of each street, where I discovered that, more than conceptual design theories, changes in the scale of street design practices—particularly involving techniques of construction and finance—have played a key role in shaping pedestrian experiences. My findings support Christopher Alexander's process-­‐based design theory, and the critical spatial theories of political economy. In my conclusion I suggest some ways that these theories might dovetail into a more holistic approach to design based on adaptive, egalitarian processes. My research shows that consideration of process is essential to any urban design theory that aims to account for the pedestrian experience of streets