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Browsing Centros UC by browse.metadata.fuente "SIPA"
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- ItemA simple low-cost approach for transport parameter determination in mountain rivers(2021) Castillo, Daniela; Runkel, Robert L.; Duhalde, Denisse; Pasten Gonzalez, Pablo Arturo; Arumí, José L.; Oyarzún, Jorge; Núñez, Jorge; Maturana, Hugo; Oyarzún, Ricardo; Centro de Desarrollo Urbano Sustentable (Chile)A simplified low-cost approach to experimentally determine transport parameters inmountain rivers is described,with an emphasis on the longitudinal dispersion coefficient(DL). The approach is based on a slug injectionof table salt (NaCl) as a tracer and specificconductance readings at different locations downstream of the injection spot. Observedspecific conductance readings are fit using the advection-dispersion equation withOTIS-P, yielding estimates of cross-sectional area and longitudinal dispersion coefficientfor various stream reaches. Estimates of theDLare used to assess the accuracy of sev-eral empirical equations reported in the literature. This allowed the determination ofcomplementary transport parameters related to transient storage zones. The empiricalequations yielded rather highDLvalues, with some reaching up an order of magnitudehigher to those obtained from tracer additions and OTIS-P. Overall, the proposedapproach seems reliable and pertinent for river reaches of ca. 150 m in length.
- ItemCoastal Wetlands: Ecosystems Affected by Urbanization?(2020) Rojas Quezada, Carolina Alejandra; Novoa, Vanessa; Rojas, Octavio; Ahumada-Rudolph, Ramón; Sáez, Katia; Fierro, Pablo; Centro de Desarrollo Urbano Sustentable (Chile)Coastal wetlands are ecosystems that provide multiple benefits to human settlements; nonetheless, they are seriously threatened due to both a lack of planning instruments and human activities associated mainly with urban growth. An understanding of their functioning and status is crucial for their protection and conservation. Two wetlands with different degrees of urbanization, Rocuant-Andalién (highly urbanized) and Tubul-Raqui (with little urbanization), were analyzed using temperature, salinity, dissolved oxygen, pH, turbidity, granulometry, fecal coliform, and macroinvertebrate assemblage variables in summer and winter. In both wetlands marked seasonality in salinity, temperature and sediment texture classification, regulated by oceanic influence and changes in the freshwater budget, was observed. In the Rocuant-Andalién wetland, the increases in pH, dissolved oxygen, gravel percentage, and coliform concentration were statistically significant. Urbanization generated negative impacts on macroinvertebrate assemblage structure that inhabit the wetlands; greater richness and abundance (8.5 times greater) were recorded in the Tubul-Raqui wetland than in the more urbanized wetland. The multivariate statistical analysis reflects the alteration of these complex systems.
- ItemCopper entrapment and immobilization during cement hydration in concrete mixtures containing copper tailings(2021) Vargas, Felipe; Alsina, Marco A.; Gaillard, Jean-François; Pasten Gonzalez, Pablo Arturo; López, Mauricio; Centro de Desarrollo Urbano Sustentable (Chile)The use of copper tailings as supplementary cementitious material can reduce the environmental impacts ofconcrete production and the mining industry. A key concern limiting its application is the potential leaching oftoxic metals from the cementitious matrix, especially copper. To analyze and reduce the risk of leaching, themechanisms by which copper is entrapped in the cementitious matrix were investigated, by combining micro-scopic and spectroscopic approaches. Decreasing the water-to-binder ratio was statistically relevant to reducecopper leaching. Scanning Electron Microscope micrographs allowed to spatially localize enriched copperclusters within the cementitious hydration products. In the early stages of the cementitious hydration (i.e., 24 h),no spatial correlation between copper and hydration products was found; however, after seven days, copper wasspatially associated with calcium silicate hydrates. Cu K-edge X-ray absorption near edge structure spectroscopyprovided insights into the chemical speciation of copper in the cementitious matrix. It showed that copper sulfideand oxide phases persisted, whereas the copper sulfate phases were prone to dissolution and reprecipitation ascupric hydroxides induced by the relatively high pH from calcium hydroxides formed during hydration. Pro-moting the formation of hydration products can further reduce copper leaching from the alkaline cementitiousmatrix. A better understanding of metal entrapment mechanisms could lead to new strategies that reduce themobility of toxic elements when using copper tailings, increasing their use as a replacement of cement. With thisknowledge, it is expected to answer if it is possible to improve the copper entrapment into the cementitiousmatrix and if there is a risk of leaching once is entrapped.
- ItemEmployment and sustainability: the relation between precarious work and spatial inequality in the neoliberal city(2022) Señoret Swinburn, Andrés; Ramírez Silva, María Inés; Rehner, Johannes; Pontificia Universidad Católica de Chile; Pontificia Universidad Católica de Chile; Centro de Desarrollo Urbano Sustentable (Chile)The creation of employment opportunities is a key factor to economic growth, but when pursuing sus tainable development, work arrangements must also be fair and stable. In contrast, precarious employ ment is a common and serious limitation to prospects for development and personal well being in Latin American cities. Discussing this phenomenon in the developing world requires considering the ongoing transformation of the neoliberal urban labour market, the commodity-driven economic struc ture, and questioning how such features relate to the likelihood of urban sustainable development. The present study addresses precarity in urban labour markets and subjective perceptions of stability and prospects and asks how marginalisation and fragmented urban spaces in a neoliberal context relate to the structural characteristics of precarious labour. This relationship between labour and space is anal ysed based on survey data from different types of neighbourhoods in Chile’s two largest metropolitan areas – Santiago and Concepción – using multilevel regression and ANOVA. Our study finds that precar ious employment and poor prospects replicate and reinforce typical territorial inequalities and thus con stitute a serious limitation for sustainable development. We conclude that the current labour market, the features of neoliberal extractivism, and weak formal social protection are obstructing urban development that is sustainable in terms of employment. Thus, the conceptual debate on sustainability and urban pol icy should focus more on the negative effects of precarious employment and its particular relation to spatial fragmentation in growing urban areas.
- ItemPandemic-related streets transformations: accelerating sustainable mobility transitions in Latin America(2021) Vecchio, Giovanni; Tiznado Aitken, Ignacio Andrés; Mora Vega, Rodrigo; Centro de Desarrollo Urbano Sustentable (Chile)The COVID-19 pandemic and the need for physical distancing in public spaces have significant effects on sustainable mobility initiatives. Many cities around the world promoted temporary transformations of streets, redistributing road space to create emergency cycleways and expand sidewalks to allow the movement of people while granting a certain physical distance between people. While Europe and, to a lesser extent, North America have initially led these initiatives, Latin America has soon followed suit, without much of their technical experience, governance, resources and sometimes public acceptance for sustainable mobility. The paper examines if and how the major disruptive event posed by the COVID-19 has reconfigured sustainable mobility initiatives in Latin American cities. Interviewing key decision-makers, the paper reviews five initiatives across the region to examine the typology of interventions promoted and the spaces involved, the governance schemes that allowed them and the public acceptance towards such measures. The analysis demonstrates that the COVID-19 pandemic has fostered a faster adoption of sustainable mobility measures such as emergency cycleways, street pedestrianisations and other traffic calming initiatives, facilitating the creation of new coalitions and the public acceptance of these interventions thanks to the sense of urgency generated by the pandemic.
- ItemSettling of copper-rich suspended particles from acid drainage neutralization as a function of chemical composition and particle size distribution(2022) Montecinos, Mauricio; Briso, Alejandro; Vega, Alejandra; Pasten Gonzalez, Pablo Arturo; Centro de Desarrollo Urbano Sustentable (Chile)The attenuation of total and dissolved metals from acid drainage (AD) results from the interaction of physical andchemical processes occurring during and after AD neutralization in impacted rivers. Chemical removal occurswhen dissolved metals are transferred into fine particles or flocs, while physical removal occurs when metal-richsuspended particles are deposited from the water column onto the riverbed. Most works studying metal atten-uation in rivers focus on characterizing chemical and physical removal processes separately, yet these processesoften interact and take place concurrently. The fate of copper (Cu) in particle suspensions formed from partialneutralization of AD was studied using a settling column coupled to a device that measured particles size dis-tribution in situ, with minimal floc disruption. Chemical composition, particles size distribution, and total sus-pended solids (TSS) were measured as particles settled. The physical removal of freshly formed particles wasenhanced by aluminum (Al), promoting the formation of larger particles and higher rates of TSS removal.However, Fe promoted higher partition of Cu onto particles, controlling its chemical removal. While the rate ofCu association to particles increased over time, TSS settled out from solution within the initial hour, regardless ofthe chemical composition within the range of tested conditions. Therefore, different remediation strategies maybe applied depending on the goal for removal (e.g., removal of TSS, removal of Cu) and water composition. Thesestrategies must consider chemical conditions (i.e., pH and concentrations of Al and Fe), settling times, and mixingconditions during particles formation for an optimal removal.
- ItemUrban Fabric Patterns on Urban Wetland(2021) Rojas Quezada, Carolina Alejandra; Díaz, Sebastián; Munizaga, Juan; Trapani, Ferdinando; Mohareb, Nabil; Rosso, Federica; Kolokotsa, Denia; Maruthaveeran, Sreetheran; Ghoneem, Mahmoud; Centro de Desarrollo Urbano Sustentable (Chile)The Author(s), under exclusive license to Springer Nature Switzerland AG.Latin American cities have experienced rapid urbanization and with it the social and environmental challenges caused by urban sprawl. Over the last decades, this increase has led to strong wetland area loss and fragmentation. It has negatively impacted its ecological value and biodiversity, and ignored their ecosystems services. This study analyzes wetland urbanization patterns in the Metropolitan area of Concepción (South of Chile). It proposes a characterization of the urban fabrics using the urbanization variables of density of population and dwellings, distances to roads and city center, and % covered by roads and green areas surrounding the wetland, in order to evaluate which urban variable explains the increase in urbanization, reducing recreation services for the well-being of residents from the different urban fabrics. In Chilean cities, urban wetlands are typically built on with dwellings that are not friendly with the natural environment. The urbanization intensity is modeled with a linear regression ordinary least squares (OLS), and predictions or a model of the dependent variable in terms of its relationships to a set of explanatory urban variables is generated. The built-up area (BA) is the dependent variable, and the variables of densities, distances, green spaces, and roads are independent. A discussion about the effect of spatial urbanization on urban wetlands is achieved, and the urbanization intensity is determined. The study adds to the discussion about spatial patterns and urban processes in urban landscapes; the results are inputs for natural planning and designing for people who intend to use urban wetlands in cities as nature-based solutions
- ItemUrban Fabrics to Eco-Friendly Blue–Green for Urban Wetland Development(2021) Rojas Quezada, Carolina Alejandra; Jorquera Guajardo, Felipe Ignacio; Pontificia Universidad Católica de Chile; Centro de Desarrollo Urbano Sustentable (Chile)