2,630 research outputs found
Influence of Development on Peri-urban Headwater Streams in Calgary, Alberta
The natural connection between surface water and groundwater is inevitably altered by urban development. However, the degree of alteration is dependent on the physical and climatic characteristics of a watershed as well as the development characteristics. The goal of this study was to compare a developed and an undeveloped headwater catchment in Calgary, Alberta, to understand the influence of urbanization on streamflow response to precipitation, groundwater contributions to streamflow, and the spatial and temporal variability of streamflow in a low relief, semi-arid landscape. Hydrometric measurements of streamflow, groundwater, and precipitation were used in conjunction with electrical conductivity and stable water isotopes to compare streamflow regimes and assess the impact of development. The developed Sage Hill ravine (SHR) stream had significantly smaller runoff ratios and smaller maximum event water fractions than the undeveloped Glacier Ridge ravine (GRR) stream, which was attributed to the capture and rerouting of urban stormwater away from the stream. Groundwater was shown to be an essential source of flow to both streams. Baseflow separation and stable water isotopes showed that 95% and 86% of the cumulative streamflow volume in SHR and GRR, respectively, was from baseflow sourced from shallow groundwater. Additionally, spatial and temporal differences in streamflow between SHR and GRR were attributed to the geologic heterogeneity of the shallow subsurface. Although this study did not directly identify cause-and-effect relationships of streamflow characteristics and urban development, it did identify the importance of effective area, groundwater, and geologic heterogeneity on the generation of streamflow. These findings will be useful for improving our understanding of how future development might impact streamflow, informing urban water resource management, and protecting valuable urban ecosystems
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Timing, origin, and potential global connections of mid-Ediacaran phenomena in South Australia and eastern California
Mid-Ediacaran incised valleys in the Johnnie Formation of eastern California (the Johnnie valleys) and the Wonoka Formation of South Australia (the Wonoka canyons) are of interest for their unusually large scale and broad time concordance with the largest negative carbon-isotope anomaly in Earth history (the Shuram excursion) and the emergence of multicellular life (the Ediacara fauna). The Johnnie valleys and Wonoka canyons have been widely accepted as originating in a submarine setting at a continental margin. My new data suggest an alternative scenario: that both features were cut subaerially concomitant with sea-level lowering in excess of 200 m, and were subsequently drowned and filled by marine sediments.
Critical evidence includes 1) the presence in the basal fill of both valley systems of polymictic conglomerate/breccia with a quartz sand matrix that is locally associated with stratified quartz sandstone, suggesting both local and far-traveled fill components; 2) multiple upward-fining, polymictic conglomerate-based cycles in the basal Wonoka canyon fill; 3) beds and blocks of giant ooid packstone-grainstone indicative of shallow marine sedimentation during the early stages of Johnnie valley filling; 4) the observed transition in the direction of paleoflow in the Wonoka from stratified boulder conglomerate to sandstone and siltstone event beds; and 5) regional restoration of the northern Flinders Ranges indicating that several deep canyons in the Wonoka are > 20 km inboard of the paleoshelf edge. Modern submarine canyons rarely incise that far into continental shelves.
My new carbon isotopic data demonstrate negative carbon-13 (δ13C) values in the basal Johnnie valley fill, indicating that like the Wonoka canyons, the Johnnie valleys are bracketed by the Shuram excursion. Additionally, in South Australia, regional allochthonous salt breakout is observed at the same stratigraphic level as the canyon-cutting unconformity, with no evidence for triggering by regional crustal shortening or deep marine non-deposition. Clasts from diapiric breccia and the basal Wonoka canyon fill share sedimentologic, petrographic, and geochemical characteristics indicating the presence of diapiric contributions to the canyon fill, and that allochthonous salt and the canyons interacted dynamically at the Earth’s surface during the Ediacaran.
Each of these observations is more consistent with the expectations of a subaerial rather than submarine setting. I hypothesize that the Johnnie valleys and Wonoka canyons were cut by a combination of fluvial incision and subaerial mass wasting, before being drowned. Sea-level lowering is thought to have been triggered by the ~580 Ma Gaskiers glaciation. My interpretation is based on high-resolution physical stratigraphic mapping supported by sub-meter scale 3-D drone imagery, geochemical analysis (δ13C, δ18O, δ26Mg, Mg/Ca), structural restoration, as well as sedimentologic and petrographic analysis. The overall interpretation has several implications for connections between mid-Ediacaran phenomena globally. Given that the Johnnie valleys and Wonoka canyons are stratigraphically bracketed by negative δ13C values putatively correlated with the Shuram excursion, my data suggest that the Shuram excursion may encompass rather than postdate the Gaskiers glaciation in eastern California and South Australia, and that the onset of the excursion may be diachronous at a global scale.
My interpretation presents the first outcrop evidence for subaerial erosion and non-deposition as a mechanism capable of triggering appreciable salt breakout. The suggested occurrence of regional isolation and rapid environmental change closely precedes the emergence of the Ediacara fauna, and presents new context for the organisms and the sediments in which they are recorded
Short‐term biogeomorphology of a gravel‐bed river: Integrating remote sensing with hydraulic modelling and field analysis
In recent decades, fluvial geomorphology and ecohydraulic research have extensively used field observations, remote sensing or hydrodynamic modelling to understand river systems. This study presents an innovative approach that combines field surveys, Light Detection and Ranging (LiDAR)-based topographical and biomass analyses and model-derived hydro-morphodynamic geostatistics to examine short-term bio-geomorphological changes in the wandering gravel-bed Orco River in Italy. Our primary hypothesis is that hydro-morphological variables can be robust descriptors for riparian vegetation distribution. From a geomorphological perspective, our study con-firms the prevalent wandering behaviour of the Orco River. Moreover, we identified a widening trend in braiding and anabranching sections, particularly downstream.This is evident because of hotspots of flood-induced morphological reactivation and the redistribution of sediments from the riverbed to lateral bars, resulting in a multi-thread pattern. Our analysis reveals a net increase in biomass during the observation period despite frequent flood disturbances. We attributed it to two opposing bio-geomorphological dynamics: the reduced flow disturbance in some regions due to flood-induced geomorphological changes and the self-healing of lateral connectivity through river wandering. Such a net increase indicates that transitional rivers store carbon in the form of vegetation biomass due to their short-term morphological instability and the different timescales between vegetation and morphological adjustments. Finally, we supported our initial hypothesis with three key findings: (i) a signature of vegetation not just on topography but also on hydro-morphological conditions, summarised by inundation probability; (ii) the lower variance in vertical topographical changes in vegetated areas compared with bare ones; and (iii) the introduction of a new parameter, named inundation viscosity, derived from the product of mean bed shear stress and average inundation duration, as a discriminating factor for colonisation conditions. These results underscore the value of our comprehensive approach
The high-resolution Global Aviation emissions Inventory based on ADS-B (GAIA) for 2019–2021
Aviation emissions that are dispersed into the Earth's atmosphere affect the climate and air pollution, with significant spatiotemporal variation owing to heterogeneous aircraft activity. In this paper, we use historical flight trajectories derived from Automatic Dependent Surveillance–Broadcast (ADS-B) telemetry and reanalysis weather data for 2019–2021 to develop the Global Aviation emissions Inventory based on ADS-B (GAIA). In 2019, 40.2 million flights collectively travelled 61 billion kilometres using 283 Tg of fuel, leading to CO2, NOX and non-volatile particulate matter (nvPM) mass and number emissions of 893 Tg, 4.49 Tg, 21.4 Gg and 2.8 × 1026 respectively. Global responses to COVID-19 led to reductions in the annual flight distance flown and CO2 and NOX emissions in 2020 (−43 %, −48 % and −50 % respectively relative to 2019) and 2021 (−31 %, −41 % and −43 % respectively), with significant regional variability. Short-haul flights with durations < 3 h accounted for 83 % of all flights but only for 35 % of the 2019 CO2 emissions, while long-haul flights with durations > 6 h (5 % of all flights) were responsible for 43 % of CO2 and 49 % of NOX emissions. Globally, the actual flight trajectories flown are, on average, ∼ 5 % greater than the great circle path between the origin and destination airports, but this varies by region and flight distance. An evaluation of 8705 unique flights between London and Singapore showed large variabilities in the flight trajectory profile, fuel consumption and emission indices. GAIA captures the spatiotemporal distribution of aviation activity and emissions and is provided for use in future studies to evaluate the negative externalities arising from global aviation.</p
Cycling Through the Pandemic : Tactical Urbanism and the Implementation of Pop-Up Bike Lanes in the Time of COVID-19
Provides an international overview on how tactical urbanism was implemented to give more space to cycling
Demonstrates the conceptual framework surrounding tactical urbanism and how it plays out theoretically
Proposes new methodological insights to understand the effects of tactical urbanism intervention
Revisiting the capitalization of public transport accessibility into residential land value: an empirical analysis drawing on Open Science
Background: The delivery and effective operation of public transport is fundamental for a for a transition to low-carbon emission transport systems’. However, many cities face budgetary challenges in providing and operating this type of infrastructure. Land value capture (LVC) instruments, aimed at recovering all or part of the land value uplifts triggered by actions other than the landowner, can alleviate some of this pressure. A key element of LVC lies in the increment in land value associated with a particular public action. Urban economic theory supports this idea and considers accessibility to be a core element for determining residential land value. Although the empirical literature assessing the relationship between land value increments and public transport infrastructure is vast, it often assumes homogeneous benefits and, therefore, overlooks relevant elements of accessibility. Advancements in the accessibility concept in the context of Open Science can ease the relaxation of such assumptions.
Methods: This thesis draws on the case of Greater Mexico City between 2009 and 2019. It focuses on the effects of the main public transport network (MPTN) which is organised in seven temporal stages according to its expansion phases. The analysis incorporates location based accessibility measures to employment opportunities in order to assess the benefits of public transport infrastructure. It does so by making extensive use of the open-source software OpenTripPlanner for public transport route modelling (≈ 2.1 billion origin-destination routes). Potential capitalizations are assessed according to the hedonic framework. The property value data includes individual administrative mortgage records collected by the Federal Mortgage Society (≈ 800,000). The hedonic function is estimated using a variety of approaches, i.e. linear models, nonlinear models, multilevel models, and spatial multilevel models. These are estimated by the maximum likelihood and Bayesian methods. The study also examines possible spatial aggregation bias using alternative spatial aggregation schemes according to the modifiable areal unit problem (MAUP) literature.
Results: The accessibility models across the various temporal stages evidence the spatial heterogeneity shaped by the MPTN in combination with land use and the individual perception of residents. This highlights the need to transition from measures that focus on the characteristics of transport infrastructure to comprehensive accessibility measures which reflect such heterogeneity. The estimated hedonic function suggests a robust, positive, and significant relationship between MPTN accessibility and residential land value in all the modelling frameworks in the presence of a variety of controls. The residential land value increases between 3.6% and 5.7% for one additional standard deviation in MPTN accessibility to employment in the final set of models. The total willingness to pay (TWTP) is considerable, ranging from 0.7 to 1.5 times the equivalent of the capital costs of the bus rapid transit Line-7 of the Metrobús system. A sensitivity analysis shows that the hedonic model estimation is sensitive to the MAUP. In addition, the use of a post code zoning scheme produces the closest results compared to the smallest spatial analytical scheme (0.5 km hexagonal grid).
Conclusion: The present thesis advances the discussion on the capitalization of public transport on residential land value by adopting recent contributions from the Open Science framework. Empirically, it fills a knowledge gap given the lack of literature around this topic in this area of study. In terms of policy, the findings support LVC as a mechanism of considerable potential. Regarding fee-based LVC instruments, there are fairness issues in relation to the distribution of charges or exactions to households that could be addressed using location based measures. Furthermore, the approach developed for this analysis serves as valuable guidance for identifying sites with large potential for the implementation of development based instruments, for instance land readjustments or the sale/lease of additional development rights
Towards electric bus system: planning, operating and evaluating
The green transformation of public transportation is an indispensable way to achieve carbon neutrality. Governments and authorities are vigorously implementing electric bus procurement and charging infrastructure deployment programs. At this primary but urgent stage, how to reasonably plan the procurement of electric buses, how to arrange the operation of the heterogeneous fleet, and how to locate and scale the infrastructure are urgent issues to be solved. For a smooth transition to full electrification, this thesis aims to propose systematic guidance for the fleet and charging facilities, to ensure life-cycle efficiency and energy conservation from the planning to the operational phase.One of the most important issues in the operational phase is the charge scheduling for electric buses, a new issue that is not present in the conventional transit system. How to take into account the charging location and time duration in bus scheduling and not cause additional load peaks to the grid is the first issue being addressed. A charging schedule optimization model is constructed for opportunity charging with battery wear and charging costs as optimization objectives. Besides, the uncertainty in energy consumption poses new challenges to daily operations. This thesis further specifies the daily charging schedules with the consideration of energy consumption uncertainty while safeguarding the punctuality of bus services.In the context of e-mobility systems, battery sizing, charging station deployment, and bus scheduling emerge as crucial factors. Traditionally these elements have been approached and organized separately with battery sizing and charging facility deployment termed planning phase problems and bus scheduling belonging to operational phase issues. However, the integrated optimization of the three problems has advantages in terms of life-cycle costs and emissions. Therefore, a consolidated optimization model is proposed to collaboratively optimize the three problems and a life-cycle costs analysis framework is developed to examine the performance of the system from both economic and environmental aspects. To improve the attractiveness and utilization of electric public transportation resources, two new solutions have been proposed in terms of charging strategy (vehicle-to-vehicle charging) and operational efficiency (mixed-flow transport). Vehicle-to-vehicle charging allows energy to be continuously transmitted along the road, reducing reliance on the accessibility and deployment of charging facilities. Mixed flow transport mode balances the directional travel demands and facilities the parcel delivery while ensuring the punctuality and safety of passenger transport
Narrative Potential of Menus in Video Games
openNei videogiochi, il menu principale è la casella degli strumenti del giocatore. Lo scopo del menu principale di un videogioco si trova anche nella nostra realtà per cose come una borsa personale o una casa. La struttura e il contenuto di questi oggetti raccontano la vita di una persona. Queste sono cassette degli attrezzi che descrivono gli obiettivi, le azioni e gli elementi importanti di come uno sceglie vivere la sua vita. Comparativamente, il layout e il contenuto del menu principale raccontano la storia del giocatore nel gioco. Il menu principale può anticipare la narrazione e può indicizzare l'interazione con il mondo di gioco. Dimostra i controlli di base del gioco e la logica dell'interfaccia. Per questi motivi, il menu principale può essere considerato l'offerta principale del gioco. Questo estratto è legato a una tesi finale che esaminerà le narrazioni, l'importanza e la presenza di come i menu principali sono organizzati, presentati e utilizzati.
Il menu principale è un elemento visivo e narrativo che è all'interno dell'interfaccia non limitato ad essere parte del codice di programmazione di un gioco. Gli obiettivi principali e lo scopo del gioco saranno presenti nel menu principale, indipendentemente se il giocatore sceglie di giocare il gioco come previsto. Quali sono le opzioni identificano gli elementi importanti del gioco. Dove e come gli elementi sono posizionati identificano la loro gerarchia e le relazioni. Come vengono utilizzate le opzioni, facendo riferimento all'input dell'utente, sono collegate all'hardware del gioco e a come il giocatore si muove all'interno del gioco. La forma del funzionamento del menu principale rifletterà e dimostrerà come viene utilizzato l'hardware e la logica dell'interfaccia. Queste considerazioni possono dimostrare come il menu principale funge da guida al gioco come offerta primaria dimostrando come giocare il gioco. Il menu principale come elemento visivo e narrativo si trova in tutti i giochi moderni, con alcune eccezioni, perché è parte integrante dell'interfaccia e della storia del gioco.
La mia tesi introdurrà la mia metodologia e lo stato dell'arte sui principali menu nel campo interdisciplinare degli studi di gioco. Gli studi di casi includeranno giochi digitali del franchise Pokémon, la saga di The Legend of Zelda, Animal Crossing e Katamari Damaci. Questo studio spera di portare consapevolezza allo studio del menu principale come più di una semplice interfaccia. Si tratta di un elemento narrativo importante di un gioco che dovrebbe essere un argomento ben studiato all'interno di studi di gioco. I videogiochi possono essere classificati in base al menu principale e l'interfaccia, aggiungendo ai generi tradizionali che vengono utilizzati. Può essere possibile che le recenti tendenze e cambiamenti nei videogiochi che vengono creati dalla tecnologia più recente non sono del tutto nuovi. Questi giochi potrebbero essere realizzando modi che i vecchi giochi erano originariamente destinati ad essere giocato.In videogames, the main menu is the player’s toolbox. The purpose of the main menu to a video game is also found in our reality to things such as a personal bag or a home. The structure and contents of these objects both tell a story of a person’s life. These are toolboxes that outline the goals, actions, and important elements of how one chooses to live his life. Comparatively, the layout and contents of the main menu tell the story of the player in the game. The main menu can anticipate narrative and it can index interaction with the game-world. It demonstrates the basic controls of the game and the interface’s logic. For these reasons, the main menu can be considered the game’s primary affordance. This abstract is related of a final thesis which will look at the narratives, importance, and presence of how main menus are organized, presented, and used.
The main menu is a visual and narrative element that is within the interface not limited to being part of a game’s programming code. The main objectives and purpose of play will be present in the main menu regardless if the player chooses to play the game as intended. What the options are identify the important elements of play. Where and how the elements are placed identify their hierarchy and relationships. How the options are used, referring to user input, are linked to the game’s hardware and how the player is moving within the game. The form of the main menu’s operation will reflect and demonstrate how the hardware is used and the interface’s logic. These considerations can prove how the main menu acts as a guide to the game as primary affordance by demonstrating how to play the game. The main menu as a visual and narrative element is found in all modern games, with some exceptions, because it is an integral part of the game's interface and story.
My thesis will introduce my methodology and the state of art about main menus in the interdisciplinary field of game studies. Case studies will include digital games from the Pokémon franchise, the saga of The Legend of Zelda, Animal Crossing, and Katamari Damaci. This study hopes to bring awareness to studying the main menu as more than just an interface. It is an important narrative element of a game that should be a well-studied topic within game studies. Videogames can be categorized based on main menu and interface, adding to the traditional genres that are used. It may be possible that recent trends and changes in videogames that are created from newer technology are not entirely new. These games could be realizing ways that older games were originally intended to be played
Los puentes peatonales, ¿enemigos de la accesibilidad universal? el caso de la intersección de la Av. Néstor Gambetta y la Av. La Playa
Disfrutar de un espacio urbano accesible es el derecho de toda persona con discapacidad
y es la obligación del Estado peruano cooperar para asegurar la accesibilidad a estas personas
(Naciones Unidas, 2016a). En este sentido, es necesario evaluar la infraestructura vial actual con
el fin de determinar si los elementos que la conforman, realmente, satisfacen las necesidades de
desplazamiento de los peatones más vulnerables, las personas sin autonomía. Con este fin, se
evaluó a la instalación de un cruce a desnivel que es el puente peatonal, y, así, responder si
promueve la accesibilidad universal o no.
La presente investigación tuvo como principal objetivo determinar si fue adecuada la
instalación del puente peatonal con rampas en la intersección de la Av. Néstor Gambetta y la Av.
La Playa. Se desdobló este objetivo en tres objetivos específicos: Describir la opinión de los
peatones respecto al puente peatonal construido, determinar el nivel de accesibilidad peatonal que
se alcanza en el área de estudio y si se logra la integración del puente peatonal construido, y
diseñar una propuesta para mejorar las condiciones de circulación peatonal en la zona de estudio.
La metodología se basó en un enfoque mixto. Por un lado, en el enfoque cualitativo está
el diagnóstico del nivel de accesibilidad del entorno peatonal, a través de la observación y el
registro fotográfico. Por otro lado, como parte del enfoque cuantito, se aplicaron encuestas
presenciales a una muestra no probabilística, se contó los flujos peatones y vehiculares, y se
evaluó la eficiencia de la propuesta de rediseño vial que excluye al puente peatonal a través del
software VISSIM 8.
Los resultados obtenidos respaldan la conclusión de que la construcción del puente
peatonal de la intersección estudiada no fue adecuada, afirmación que se respalda en tres
argumentos. El primero es que la opinión compartida por las personas sin autonomía es que el
puente es la opción menos accesible, o, incluso, inaccesible. Además, les provoca cansancio
producto del esfuerzo extra para recorrerlo, les demanda más tiempo para lograr cruzar la avenida,
y, durante el recorrido por los tramos del puente, no se sienten seguros. El segundo motivo es que
el entorno peatonal actual es calificado con bajo nivel de accesibilidad que impide la formación
de itinerarios peatonales accesibles y continuos, por lo que, al incluir al puente, este no logra
integrarse y, mucho menos, logra mejorar las condiciones de desplazamiento para las personas
sin autonomía. El último argumento es que, es posible mejorar las condiciones de circulación para
brindar mayor accesibilidad al peatón, a la par de beneficiar la circulación de los vehículos en un
escenario donde no existe el puente peatonal
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