Browsing by Author "Munizaga, Juan"

Now showing 1 - 13 of 13
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    A new method to evaluate the vulnerability of watersheds facing several stressors: A case study in mediterranean Chile
    (2019) Arriagada, Loretto; Rojas, Octavio; Arumí, José Luis; Munizaga, Juan; Rojas Quezada, Carolina Alejandra; Farias, Laura; Vega, Claudio
    Freshwater systems are subjected to multiple anthropogenic stressors and natural disturbances that act as debilitating agents and modifiers of river systems, causing cumulative and synergistic effects that deteriorate their health and result in watershed vulnerability. This study proposes an easy-to-apply spatial method of watershed vulnerability evaluation using Geographic Information Systems (GIS) in the Andalién River watershed, located in the Chilean mediterranean. A watershed vulnerability index (WVI) based on three sub-indices – anthropogenic stressors, environmental fragility and natural disturbances – was developed. To determine the index grouping weights, expert surveys were carried out using the Delphi method. We subsequently normalized and integrated the factors of each sub-index with relative weights. The ranges of each thematic layer were re-classified to establish vulnerability scores. The watershed was divided into three sections: headwaters zone, transfer zone and depositional zone. The watershed vulnerability index showed that 41% of the watershed had very low vulnerability and 42% had medium vulnerability, while only 1% – in the depositional zone – had high vulnerability. A one-way ANOVA was carried out to analyze the vulnerability differences among the three sections of the watershed; it showed significant differences (F (2, 16) = 8.15: p < 0.05). The a posteriori test showed differences between the headwaters and depositional zones (Tukey test, p = 0.005) and between the transfer and depositional zones (Tukey test, p = 0.014). To validate the WVI, water quality was measured at 16 stations in the watershed; there was a significant correlation between vulnerability level and NO2− levels (r = 0.8; p = 0.87; α = 0.05) and pH (r = 0.8; p = 0.80; α = 0.05). The WVI showed the cumulative effects of multiple stressors in the depositional zone of the watershed. This is the first study to evaluate and validate non-regulated watershed vulnerability with GIS using multiple anthropogenic and natural stressors.
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    Accessibility disturbances to the biodiversity of urban wetlands due to built environment
    (2022) Rojas Quezada, Carolina Alejandra; Sepúlveda Zúñiga, Einer Alexander; Jorquera Guajardo, Felipe Ignacio; Munizaga, Juan; Pino, Joan; Pontificia Universidad Católica de Chile. Instituto de Estudios Urbanos y Territoriales; Universidad de Concepción; Universidad Autónoma de Barcelona
    Urbanization and urban sprawl in Latin America has led to the social and environmental challenges such as lossand fragmentation of wetland areas, negatively impacting their ecological and social benefits and biodiversity.Urban wetlands are ecosystems that are essential to Latin American cities and are recognized for both theirprotection against flooding and use as recreational spaces. Additionally, accessibility to urban wetlands can alsoincrease urban residents’ well-being. This study analyzes the city model of an urban wetland in the GreaterConcepcion ´ area (Chile, South America), an area that has recently experienced urban sprawl. First, it identifies the urban fabric and modelling the urban variables of density, distance, roads, and green areas surrounding an inland wetland. Second, it evaluates the accessibility to the wetland and its effect on plant composition using a biodiversity indicator (% native and introduced plants). Literature and social enviroment movements has been showing the Concepcion ´ city is growing with no regard for its urban wetland, and its biodiversity is not considered in urban planning. Still, urban wetland remains does have potential benefits for people, species, and possible recreational opportunities. The study contributes to the discussion of the unsustainable spatial model of urbanization interacts with wetland accessibility and with disturbance to biodiversity; the results represent input for urban planning in order to restoring an integrated wetland within cities and improve accessibility by including natural urban wetlands as green infrastructure
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    Mapping coastal wetlands using satellite imagery and machine learning in a highly urbanized landscape
    (2022) Munizaga, Juan; García, Mariano; Ureta, Fernando; Novoa, Vanessa; Rojas, Octavio; Rojas Quezada, Carolina Alejandra; CEDEUS (Chile)
    Coastal wetlands areas are heterogeneous, highly dynamic areas with complex interactions between terrestrial and marine ecosystems, making them essential for the biosphere and the development of human activities. Remote sensing offers a robust and cost-efficient mean to monitor coastal landscapes. In this paper, we evaluate the potential of using high resolution satellite imagery to classify land cover in a coastal area in Concepción, Chile, using a machine learning (ML) approach. Two machine learning algorithms, Support Vector Machine (SVM) and Random Forest (RF), were evaluated using four different scenarios: (I) using original spectral bands; (II) incorporating spectral indices; (III) adding texture metrics derived from the grey-level covariance co-occurrence matrix (GLCM); and (IV) including topographic variables derived from a digital terrain model. Both methods stand out for their excellent results, reaching an average overall accuracy of 88% for support vector machine and 90% for random forest. However, it is statistically shown that random forest performs better on this type of landscape. Furthermore, incorporating Digital Terrain Model (DTM)-derived metrics and texture measures was critical for the substantial improvement of SVM and RF. Although DTM did not increase the accuracy in SVM, this study makes a methodological contribution to the monitoring and mapping of water bodies’ landscapes in coastal cities with weak governance and data scarcity in coastal management.
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    Restoration of the Rocuant Andalién Coastal Wetland (Metropolitan Concepción, Chile): A Transdisciplinary Proposal
    (Springer, 2024) Rojas, Octavio; Rojas Quezada, Carolina Alejandra; Munizaga, Juan; Soto, Evelyn; Rueda, Ivonne; Mallea, Grace; Álvarez, Loreto; Barrera , Francisco de la
    After securing wetland protection, it is critical to implement restoration actions aimed at restoring their ecological integrity by stopping the negative pressures and reestablishing the ecological functions, including ecosystem services and connectivity. This study proposes a set of restoring areas for the Rocuant-Andalién coastal wetland (2000 ha; Metropolitan Concepción, Chile), which has been highly degraded by the rapid development of urban, port, road, and agricultural lands. To identify the priority potential restoration areas (PRA), we adapted the IUCN-ROAM methodology, including: GIS and ecological connectivity analyses, ecosystem services evaluation, and stakeholder consultation at two spatial scales. For the watershed scale, we identified 45 PRA covering 6053 ha and 17 PRA covering 418 ha for the wetland scale, mainly located in the bottom section of the watershed. Stakeholders prioritized five potential restoration areas (PRA) primarily due to their heightened vulnerability to urbanization and potential landfill exposure. Priority restoration areas have the potential to incorporate water-sensitive design measures. The existing robust collaboration between the public sector and citizen organizations will play a crucial and supportive role in implementing restoration actions within these prioritized zones. However, the tensions between the private sector and citizen organizations can weaken and impede the achievement of restoration in critical areas at both scales. Although all sectors were involved in identifying restoration priorities, there is a need to strengthen and increase the relations between all stakeholders to support the recovery of susceptible and complex natural systems like wetlands.
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    Soluciones basadas en la naturaleza para la mitigación de las inundaciones
    (Centro de Desarrollo Urbano Sustentable, 2023) Rojas Quezada, Carolina Alejandra ; Rojas, Octavio; Munizaga, Juan; Jorquera Guajardo, Felipe Ignacio; Novoa, Vanessa; CEDEUS (Chile)
    Las inundaciones pueden tener consecuencias desastrosas en las ciudades y asentamientos. Por ello, y sobre todo en años con el fenómeno del Niño, es relevante reducir las vulnerabilidades y aumentar la resiliencia mediante su mitigación y control. Por años esto se ha hecho mediante infraestructuras tradicionales o grises. El presente documento tiene por objetivo entregar recomendaciones de infraestructura adecuada para reducir los impactos que generan estos eventos por medio de soluciones basadas en la naturaleza para la zona central de Chile.
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    Spatiotemporal vegetation dynamics in a highly urbanized Chilean coastal wetland: Insights on long-term natural and anthropogenic influences
    (2024) Munizaga, Juan; Rojas, Octavio; Lagos, Bernardo; Rojas Quezada, Carolina Alejandra; Yepez, Santiago; Hernández, Esteban; Ureta, Fernando; de la Barrera, Francisco; Jato-Espino, Daniel; CEDEUS (Chile)
    This study analyzes the spatiotemporal dynamics of the vegetation of a highly urbanized coastal wetland in the 2000–2020 period, considering natural disturbances and anthropogenic stressors. The wetland system was stratified into four domains: Coastal, Intertidal, Freshwater, and Urban, differentiated by their geomorphological, topographical, and water salinity characteristics, which were validated by ground vegetation sampling. In these domains, spectral indicators of vegetation were used on 884 Landsat images in the Google Earth Engine to determine vegetation types, trends, and phenology. The start of the growing season coincides with the beginning of the Austral winter, exhibiting seasonal behavior, which was interrupted by abrupt natural disturbances such as floods and tsunamis. In addition, a progressive trend associated with the replacement of native species by exotic species was reported in areas with significant anthropogenic stressors (e.g., highways, city edges, and grazing areas), with 45 % presenting an increase in the normalized difference vegetation index. Areas far from anthropogenic stressors maintained their behavior, which is explained by natural factors such as precipitation, temperature, and evapotranspiration. The proposed method strengthens our understanding of the interrelationship between factors that modify the behavior of vegetation in coastal wetlands pressured by anthropogenic stressors and contributes to their management and protection.
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    Urban development versus wetland loss in a coastal Latin American city : lessons for sustainable land use planning
    (2019) Rojas, Carolina; Munizaga, Juan; Rojas, Octavio; Martínez; Reyes, Carolina del Pilar; Pino, Joan
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    Urban 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
    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
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    Urban Wetland Losses and Land-Use Conservation Challenges in Three Latin American Cities
    (Springer, 2024) Aldana-Domínguez, Juanita; Rojas Quezada, Carolina Alejandra; Munizaga, Juan; Moschella, Paola; Stamm, Caroline Andre; Martínez, Carolina
    Wetlands are valuable and threatened ecosystems throughout the world. They are essential for the maintenance of life and ecological balance, in addition to providing a larger number of benefits to human societies. Wetlands reduce the risk of flooding by regulating the flow of water, being essential to reduce the impacts of climate change, especially along the coasts and coastal cities of the world. Urban growth poses a risk to wetlands in and around urban areas. In this work, we quantify the loss trends of wetlands in urban areas in three Latin American countries between the years 2002 and 2019. We selected as case studies the wetlands of Aconcagua in Chile, Ciénaga de Mallorquín in Colombia, and Pantanos de Villa in Peru. Through multitemporal analysis of Quickbird satellite imagery collections, we classify land covers at 2.5-m resolution and identify areas covered by wetland. We quantify the losses and gains of the wetland areas and the areas surrounding them. We found that the three wetlands analyzed lost area, confirming the worldwide trend of loss. The Ciénaga de Mallorquín wetland was the one that decreased the most due to coastal dynamics and urbanization. The Pantanos de Villa wetland reduced its area due to the increase in urban areas that grew filling the wetland under the pressure of informal settlements and beach condominiums. Lastly, the Aconcagua wetland was reduced due to the increase in grasslands together with the increase in bare soil, also affecting the beaches and dunes. In all three case studies, urban wetlands decreased due to urban growth. For this reason, we call attention to the urgency of improving urban planning to ensure the maintenance of these key ecosystems to ensure more sustainable and resilient cities, as proposed by Sustainable Development Goal 11.
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    Urban Wetland Trends in Three Latin American Cities during the Latest Decades (2002-2019): Concón (Chile), Barranquilla (Colombia), and Lima (Peru)
    (Society of Wetland Scientists', 2020) Rojas Quezada, Carolina Alejandra; Aldana-Domínguez, Juanita; Munizaga, Juan; Moschella, Paola; Martínez, Carolina; Stamm, Caroline Andre
    Wetlands are valuable but threatened natural resources worldwide. While providing a wealth of environmental benefits, wetlands play a vital role in temporarily storing flood waters and thereby reducing the risk of damaging floods. This is important given the predicted impacts of climate change, especially along the world’s coastline and coastal cities. The continued expansion of urban areas is posing a risk to wetlands in and around metropolitan areas. In this article we examine wetland trends in urban areas in three Latin American countries – Chile, Colombia, and Peru.
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    Urban Wetlands in Latin America: Protection, Conservation, Innovation, Restoration, and Community for Sustainable and Water Sensitive Cities
    (Springer Cham, 2024) Aldana-Domínguez, Juanita; Rojas Quezada, Carolina Alejandra; Munizaga, Juan; Moschella, Paola; Stamm, Caroline Andre; Martínez, Carolina; Velásquez, Carlos Javier; Capera, Ingrid; Falfán, Ina; Zambrano, Luis; Soto, Evelyn; Teutsch, Camila; Scheuch, Teresita; Fernández, Antonio; Briceño, Felipe; Vattuone Troncoso, Catalina de los Angeles; Domínguez, Juan Carlos; Riveros, Andrés; Pichunleo, Enzo; Rojas Quezada, Carolina Alejandra
    This book is about the contribution of urban wetlands in livable cities. Urban wetlands are very valuable blue-green infrastructure spaces for human settlements, yet they are disappearing as a result of urbanization. This phenomenon is worldwide, but is particularly intense in Latin America. Although international literature has made an effort to document the multiple ecosystem services provided by these ecosystems, such as water and air cleansing, flood mitigation and recreation, among others, we want to draw attention to the fact that the loss of urban wetlands affects the sustainability of cities and future generations. Therefore, and given the weakness of public policies implemented in the region for their protection, it is essential to highlight good practices, mechanisms and strategies aimed at Protection, Conservation, Innovation, Restoration, and work with the Community, all of this hand in hand with the 17 Sustainable Development Goals.The book offers a comprehensive coverage combining the need to protect and conserve urban wetlands from the pressures of urban growth, as well as highlighting successful experiences of regulation and of course applied research aimed at nature-based solution design for flood management and wastewater treatment, restoration areas, green infrastructure plans, as well as experiences of collective work with communities in contexts of political tensions for the defense of wetlands.
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    Water footprint and virtual water flows from the Global South: Foundations for sustainable agriculture in periods of drought
    (2023) Novoa, Vanessa; Rojas, Octavio; Ahumada-Rudolph, Ramón; Arumí, José Luis; Munizaga, Juan; Barrera, Francisco de; Cabrera-Pardo, Jaime R.; Rojas Quezada, Carolina Alejandra
    Freshwater availability has decreased alarmingly worldwide, with agriculture playing a vital role in this trend. The assessment of the agricultural water footprint (WFagricultural) and virtual water flows (VWF) is fundamental not only in local water resources management and protection, but also in our understanding of the synergies between local water consumption and global markets. Thus, the WFagricultural – broken down into its components (blue, green, and gray) – of the leading 21 crops (grouped in fruit, legumes, cereals, and vegetables), grown in four basins with the most significant agricultural activity in central Chile was determined, estimated in two consecutive years 2017–2018. In addition, due to their great importance in exports, VWFs were assessed, establishing connections according to their origins and destinations. The results show that the green and gray water footprints increased significantly in the south-central basins, while blue water consumption increased in the basins of the central zone, reflecting an evident WFagricultural transition in accord with latitude and climate conditions. Furthermore, VWF showed an annual increase of 44 %, in about 116 destinations, with Asia, Europe, and North America being the preferred destinations, with annual variations of VWFblue- gray associated with increases in exports of apples, cherries, grapes, blueberries, and walnuts, market preferences and growing areas. The present study is an initial step toward sustainable agriculture in a commodity exporting country, one that is relevant in the exploitation of virtual water yet faces severe water deficit problems, distribution, and local water policies. Therefore, contributing to encouraging the efficiency and value of water in the process of a new institutional framework.