This research is an exploration of the local, place-based knowledge surrounding a degraded urban river, the Lower Neponset River and Estuary in southern Boston Harbor, Massachusetts, and its environmental restoration. Through a mixed-methods approach to sociological inquiry that included 18-months of ethnographic interviews and participant observations, Geographic Information System (GIS) mapping, archival document research, and critical environmental history, it explores the different ways local citizens interpret the river as a place of historical importance, personal nostalgia, social and family networks, neighborhood legacies, aesthetics, economic security, danger, psychological refuge, ecology, and political power. Using an interpretive analysis of the narrative, visual, and spatial data related to those meanings, it then explores how such different local, place-based interpretations can be used to inform the theory, practice and politics of urban river restoration. The research shows that recognition of the socio-cultural diversity in local citizen interpretations of the Lower Neponset River's restoration is important for environmental managers, planners, and local decision-makers to recognize alongside ecological and economic development "best-practices" (e.g., holistic watershed management, anadromous fish re-introduction, flow and function, ecosystem services, affordable housing quotas, "Smart" growth, etc.). The research recommends that environmental managers, planners, and local politicians and decision-makers give equal consideration to the socio-cultural, political, economic, and ecological factors surrounding urban rivers, and the diversity of meanings that their "restoration" conjures, in order to make strides towards ethical environmental restoration and management practices that are socially, as well as environmentally, sustainable.

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京都大学 / 新制・課程博士 / 博士(工学) / 甲第24593号 / 工博第5099号 / 新制||工||1976(附属図書館) / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 角 哲也, 准教授 竹門 康弘, 准教授 Kantoush Sameh / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

There have been growing concerns over the decline of healthy river ecosystems and the severe consequences this decline could have on biodiversity, ecosystem services, and human well-being. These concerns have led to increased efforts in river restoration around the globe, which aim to improve the ecological health and functioning of rivers. The restoration is usually done by implementing strategies such as hydromorphological adaptation and flow management. These measures, nevertheless, do not guarantee the recovery of river ecosystems. This is because there are multiple factors contributing to the success of restoration projects, which can vary depending on the specific characteristics of each river system. Habitat modeling, one of the most widely used ecological quality assessment tools for rivers, has been applied in the evaluation of restoration projects. An aquatic ecosystem is complex, and its dynamic nature requires a comprehensive understanding of the interconnections between biotic and abiotic components. These components also have a high degree of spatial and temporal variability. Therefore, it is crucial that approaches and modeling techniques be tailored to capture this dynamic. In the assessment of river restoration, for instance, habitat modeling needs to account for the changes in flow patterns, sediment transport, water quality, and habitat availability/quality for the key indicator species that result from the restoration efforts. This study addresses the need for developing an integrated approach to habitat modeling, particularly for macrozoobenthos, an important indicator of river health that plays a crucial role in the functioning of aquatic ecosystems. The primary research objective is to improve the existing modeling framework (TRiMM) by focusing on three key aspects: 1) expanding the prediction factors of physical habitat that influence habitat suitability for macrozoobenthos; 2) integrating fuzzy algorithms in the suitability assignment process; 3) incorporating species' (re-)colonization capacity and habitat temporal variability into habitat connectivity assessment. The model adopts the fuzzy logic method in the habitat module to account for the interactions between various factors described in the habitat template (Poff & Ward, 1990). Moreover, the model considers both spatial and temporal changes in habitat parameters by running a transient simulation over a specific time period relevant to the life cycle requirements of the target species. This allows for a more accurate representation of the dynamic nature of river habitats and provides valuable insights into how they may change over time. Additionally, the model incorporates species' (re-)colonization potentials into habitat connectivity analysis by considering their dispersal capabilities. This helps in understanding how changes in habitat parameters can affect the overall connectivity of river habitats, which is crucial for assessing the resilience and sustainability of the systems. The proposed transient habitat modeling (TRiMM 2.0) is applied to two case studies of low-order rivers in Germany. The first case study focuses on a river that has been restored after a period of degradation. The habitat model was tested with sampling data, and the results reveal that the model improved when additional variables related to habitat were included. The second case study was a simulation of habitat suitability and connectivity in a hypothetical river reach. Hydraulic and morphological factors (water depth, velocity, temperature, and sediment) are simulated over a period of four years using SRH-2D. The simulation results showed that hydraulic and morphological factors had a significant impact on sediment characteristics, which in turn influenced habitat suitability and connectivity. This study also highlights the importance of considering multiple variables and their interactions when assessing river habitats. Additionally, the use of transient modeling provides information about long-term changes in habitat quality and connectivity.:Abstract Kurzfassung Contents List of figures List of tables Nomencature Acknowledgement List of publications 1. General introduction 1.1. Research motivation 1.2. Statement of research objectives 1.3. Structure of the dissertation 2. Macrozoobenthos and stream’s ecology 2.1. Macrozoobenthos and their habitat 2.2. Factors influencing the distribution of macrozoobenthos 2.2.1. Food sources 2.2.2. Water quality 2.2.3. Physical habitat 2.2.4. Colonization process 2.2.5. Presence of other species 2.3. Spatial scale and temporal variability 2.4. Conclusion 3. State of the art in river habitat modeling 3.1. Habitat modeling and river ecology assessment 3.2. Habitat modeling principles 3.2.1. Habitat suitability curves method 3.2.2. Fuzzy logic method 3.2.3. Generalized additive models 3.3. Existing benthos habitat modeling 3.3.1. PHABSIM 3.3.2. RHYHABSIM 3.3.3. BITHABSIM 3.3.4. CASiMiR 3.3.5. HABFUZZ 3.4. TRiMM and further development 3.5. Conclusion 4. Basis for the modeling concept and methodological framework 4.1. Physical habitat template 4.1.1. Streamflow regime 4.1.2. Substrate regime 4.1.3. Thermal regime 4.2. Habitat connectivity 4.3. Species colonization and habitat connectivity 4.4. Analysis scales 4.5. Conclusion 5. Transient river habitat modeling for macrozoobenthos – TRiMM 2.0 5.1. Habitat model description 5.2. Input data preparation 5.2.1. Field survey 5.2.2. Hydro-morphodynamic models 5.3. Habitat suitability calculation 5.4. Patch-building and patch dynamics analysis 5.5. Habitat connectivity calculation 5.6. Conclusion 6. Model applications 6.1. Case study 1: Simulation of habitat suitability for macrozoobenthos in a small restored stream (Saxony, Germany) Abstract 6.1.1. Introduction 6.1.2. Material and Method 6.1.3. Results 6.1.4. Discussion 6.1.5. Conclusion 6.2. Case study 2: Application of TRiMM 2.0 to simulate benthic habitat quality in a hypothetical reach of Zschopau river 6.2.1. Introduction 6.2.2. Methodology 6.2.3. Results 6.2.4. Discussion 6.2.5. Conclusion 7. Summary and future outlook 8. References

The long history of moderating watercourses to accommodate timber floating in northern Sweden lay the ground for river restorations. One restoration method is supplementing spawning gravel for Salmonidae to lay their eggs in. The success of Salmonidae reproduction is essential for the ecology in streams as well as for the economy and culture of Sweden. However, finding appropriate locations for the gravel beds, benefiting their longevity have been difficult. The aim of this study was to investigate if hydraulic and geomorphic characteristics influence mobility of 64 restored spawning beds in 11 streams in the Vindel River catchment, Sweden. Field measurements of the spawning beds condition were taken as percentage remaining and function. Metrics of fluvial power were calculated by geospatial analysis and compared to each other by a correlation model. A linear mixed effects model was made with belonging likelihood test comparing slope, drainage area, stream power proxy, distance to lake upstream, water depth over riverbed, channel width, restoration type and all variables together to the percentage remaining. The result showed that 84% of the spawning beds had moved while 71% of the beds were recorded as functioning. No significant correlation was found between any of the investigated variables by themselves or together and percentage remaining, suggesting other variables influenced mobility of the spawning gravel. Such as variations on a local-scale and variables connected to the northern hemisphere region. The lack of adequate data, subjectivity in the condition measurements and the proxy used for stream power also influenced the result.

Mapping boulders in rivers is commonly done manually with direct measurements, marking the location and size of each boulder in the field. This method is precise but time consuming and in study areas that are inaccessible by foot or has to turbulent water the danger or expense can prohibit measurements. Using Uncrewed Aerial vehicles (UAV) could prove an effective alternative method, however how accurate UAVs are for mapping boulders in rivers is yet to be determined since the ability to map submerged boulders is limited. The aim of this study is to compare boulder data derived from UAV orthophotos to in-situ field data. Additionally, I investigate if the error between the two methods is controlled by catchment- and reach- scale characteristics. Instream boulders were manually digitized from UAV orthophotos of 8 river reaches in Northern Sweden. Fewer boulders with smaller area were found for UAV, and the error between the two methods correlated with bankfull depth, water level and sediment size distribution. This highlights the importance of water level during UAV flights, since higher water levels resulted in more boulders partially or fully submerged below the water surface decreasing the amount and area of boulders found. Similar correlations between reach-scale channel characteristics were for the UAV data as for the field data showing that data derived from UAV images can be used to better understand boulder- bed rivers. Through mapping and understanding boulder distribution in pre-disturbance reference sites, UAVs can help guide river restoration in a safe, cost and time efficient way.

La connaissance de la dynamique hydrosédimentaire des rivières avant et pendant l’installation des nombreux aménagements hydrauliques depuis l’Antiquité restaient très fragmentaire en Basse-Normandie et plus largement en Europe de l’Ouest. On savait encore peu de choses sur les processus d’érosion et de sédimentation qui se sont succédés au sein des rivières normandes au cours des deux derniers millénaires et la part des forçages anthropiques et climatiques qui ont influencé ces processus. L’objectif de la thèse est donc de comprendre et de mesurer la part des héritages dans le fonctionnement actuel des rivières afin de contribuer à leur gestion contemporaine. A cette fin, des recherches géomorphologiques et géoarchéologiques ont été menées dans plusieurs vallées bas-normandes. Ces études ont mis en évidence le poids des installations hydrauliques et en particulier le développement des moulins à eau dans la modification des chenaux d’écoulement mais aussi la construction des plaines alluviales. En effet, la structuration complète du cours d’eau depuis le Moyen Âge a fortement artificialisé les formes en plan et les pentes des cours d’eau et complètement cloisonné leur linéaire. Ces transformations ont favorisé la stabilité latérale des cours d’eau et la sédimentation limoneuse par débordement au sein des plaines alluviales. L’installation de moulins s’accompagne très souvent d’une simplification du tracé en plan de la rivière. Lors de l’équipement maximal des cours d’eau normands on trouvait un moulin tous les 2500 mètres de linéaires hydrographiques. Ces transformations signifient qu’une grande partie des cours actuels sont artificiels. En effet, ces aménagements et l’accélération de la sédimentation limoneuse depuis 1000 ans sont à l’origine de la mise en place d’un équilibre dynamique aboutissant aux formes hydrosédimentaires des rivières actuelles. L’abandon de la gestion des ouvrages hydrauliques et leur destruction au cours des cinquante dernières années viennent remettre en cause cet équilibre. / In Lower Normandy, knowledge of the hydrosedimentary dynamics of rivers before and during the installation of the numerous hydraulic installations since the Roman period remains very fragmentary. Little was known about the rates of erosion and sedimentation that have occurred over the last two millennia and how climatic and anthropogenic controls have influenced these processes. Thus, the challenge of this phD is to understand and measure the role of the inherited structures and operating in the current functioning of the rivers of Lower Normandy in order to help with their contemporary management. To provide answers, geomorphological and geoarchaeological researches has been carried out in several valleys. These studies make it possible to highlight the weight of the hydraulic installations and in particular the developments related to the mills in the setting up of floodplains. Indeed, the complete structuring and management of the watercourse since the Middle Ages artificialized riverbed forms and slopes, and partitioned rivers favoring lateral stability and overflow sedimentation in the floodplain conducting in the development of completely regulated rivers. The installation of mills is accompanied locally by a simplification of the river course. At the acme of the equipment there was a mill every 2,500 meters along the rivers of Lower Normandy. These transformations mean that a large part of current courses are artificial. These structures and the increase of the overbank silt sedimentation for 1000 years are at the origin of the establishment of a dynamic equilibrium resulting in the hydrosedimentary forms of the present rivers which are largely inherited. The abandonment of the management of the hydraulic structures and their destruction during the last fifty years comes to question this balance.

Located just east of Missoula, Montana, Milltown Dam stood from 1908 to 2008 immediately downstream of the Clark Fork River’s confluence with the Blackfoot River. After the discovery of arsenic-contaminated groundwater in the nearby community of Milltown, as well as extensive deposits of contaminated sediment in the dam’s upstream reservoir, in 1981, the area was designated a Superfund site – along with much of the Upper Clark Fork Watershed. This motivated the eventual decision to remove the dam, perform environmental remediation, and reconstruct approximately five kilometers of the Clark Fork River and its floodplain. This study is part conceptual and part empirical. It describes a state-and-transition framework equipped to investigate channel evolution as well as the adjustment trajectories of other socio-biophysical landscapes. This framework is then applied to understand the post-restoration channel evolution of the Clark Fork River’s mainstem, secondary channels, and floodplain. Adopting a state-and-transition framework to conceptualize landscape evolution lets environmental managers more effectively anticipate river response under multiple disturbence scenarios and therefore use more improvisational and adaptive management techniques that do not attempt to guide the landscape toward a single and permanent end state. State-and-transition models can also be used to highlight the spatially explicit patterns of complex biophysical response. The state-and-transition models developed for the Clark Fork River demonstrate the possibility of multiple evolutionary trajectories. Neither the secondary channels nor the main channel have responded in a linear, monotonic fashion, and future responses will be contingent upon hydrogeomorphic and climatic variability and chance disturbances. The biogeomorphic adjustments observed so far suggest divergent evolutionary trajectories and that in some instances the long-term fates of the mainstem, floodplain, and secondary channels are inescapably enmeshed with one another.

A physical assessment of the Provo River Restoration Project was undertaken in order to determine how alterations to the channel were designed, the nature of as-built channel morphology, and the performance of the reconfigured channel in terms of achieving frequent (2-year recurrence) bankfull discharge and increasing transient storage. Measures of channelized and reconfigured channel morphology were obtained using total station survey, digital aerial photography, and pebble counts. Results of geomorphic analysis were compared with similar measurements made by a regional consulting company, and stream channel design data, in order to determine that intended mitigation included reducing channel capacity, increasing sinuosity, decreasing pool spacing, and decreasing the size of bed material. Reconfiguration of the channel resulted in somewhat enlarged cross-sections with reduced mean velocities, increased sinuosity, decreased pool spacing, and decreased bed substrate size. One-dimensional hydraulic modeling suggests that alterations to channel morphology have increased the bankfull channel capacity in most reaches. Modeling results illustrate the fact that the stage of the 2-year recurrence flood is below bankfull at most cross-sections. This result does not follow the intentions of channel design. However, we have observed floodplain inundation in most years since reconfiguration. The occurrence floodplain inundation is being facilitated by overbank flow at a few point locations illustrating the strengths of incorporating variability into design. Known geomorphic controls on transient storage were reconfigured in manner to potentially increase in-channel and hyporheic components of transient storage. Stream tracer tests were utilized in order to determine the degree to which these alterations affected transient storage. Numerical analysis of stream tracer tests suggests that while the relative area of transient storage increased, average residence time of water in storage, and the mass transfer rate of solute between storage and the stream did not change. This suggests that an extensive hyporheic zone may not have been established. Correlations between hydrologic and geomorphic parameters indicate that in-stream storage may have been increased, and quick-exchange hyporheic flowpaths may have been created. (295 pages)

River restoration is something that is often used to help restore watercourses that were historically used for timber floating. In these restorations, instream wood (IW) plays a big role in increasing biodiversity and habitat heterogeneity in watercourses. Uncrewed Aerial Vehicles (UAVs) have proven to be useful when monitoring changes following river restoration but there is a need for less time-consuming methods to detect IW. This study’s objective was to investigate IW following a river restoration in an alluvial reach in Vargån, Northern Sweden and how well UAVs can be used to do this. Manual digitizing of IW was done in GIS from orthomosaics of three different flight occasions: pre-restoration, directly after and one year after restoration. An object- and color-based automated image thresholding was done to investigate if it could be used to automatically detect IW. The results showed that there were differences in number of IW, volume, width, and length between the different flight occasions. There was also indication that there had been movement of IW as well as changes in cluster composition, with more clusters with a higher number of wood pieces in the latest flight occasion. The automated image thresholding was able to accurately detect IW with an accuracy of 47,4 %, but it had limitations due to natural conditions. However, it showed the possibility of using automated methods to detect IW and with improvements it could become a faster and more accessible way of detecting IW in river monitoring.