Revista Geográfica de Chile Terra Australis

Geomorphological characterization of channel heads from the La Ventana upper basin (Buenos Aires, Argentina)

Marilina Ayelén Gonzalez, Jorge Gentili, Verónica Gil — Wed, 14 Aug 2024 00:00:00 -0400

Knowing the location of channels heads and the factors that interfere with their formation are of great importance because they affect the length of the channels, drainage density, or delay times of the basin. These factors affect the flash floods that characterize the study area and represent a danger to the local population. Therefore, the objective of this research is to identify and characterize the river heads in a sector of the upper basin of the La Ventana stream (Buenos Aires Province, Argentina) and their relationship with the geomorphological variables that influence their location (height, lithology, area, slope, and length), as well as other local factors. For this analysis, the ALOS PALSAR 12,5x12,5m Digital Surface Model, Google Earth Pro^® satellite images, geological charts, and fieldwork were used. This analysis made it possible to find significant physical differences between the streams and catchment areas of the northern and southern slopes of the basin. The interpretation of the results suggests that the physical variables (slope, height, and lithology) independently are not determinants in the formation of the beginning of a channel; rather, they are the interactions that develop between them and other local factors that give rise to the formation of river courses.

Extraction of Landsat Imagery for Analysis of Mangrove Extent and Shoreline Changes

Mubarak, Maellynia Mustofa — Wed, 14 Aug 2024 00:00:00 -0400

This study aims to determine the area of Topang Island's mangrove forest, an area experiencing extreme line changes and the magnitude of the coastline change rate from 1991 to 2021 on Topang Island, Kepulauan Meranti Regency, Riau Province. The method used in this research is remote sensing and field survey. The data obtained were discussed descriptively. The results found that the calculation of wave height prediction on the coast of Topang Island was included in the low category with an average height of 0.12 meters. The research area is dominated by abrasion, based on visual observations, Topang Island has a type of peat and muddy beach. The area of mangroves on Topang Island from 2001 to 2021 saw a big change, either adding or reducing the area of mangroves. Topang Island experienced the worst abrasion in the eastern part with an average abrasion rate of 6.13 m/year, and accretion in the western part with an average accretion rate of 0.62 m/year.

From Inactive Prehispanic Archaeological Monument to Urban Scene Generator of Self-Sustainable Communities.

Wed, 14 Aug 2024 00:00:00 -0400

The pre-Hispanic archaeological monuments on the Peruvian coast, known as huacas, have pyramidal geomorphological characteristics and represent a valuable monumental heritage. The presentation focuses on the huaca of the Pueblo Joven Santa Rosa in the city of Lambayeque, Peru, with the purpose of (re)activating it as a way of protection from urban pressure, for which they propose mechanisms and strategies for integration into the city. The development is divided into three phases: first, the huaca in its current social and urban context. Then, contemporary urban strategies for action in the huaca are presented and finally, prospective scenarios are proposed. Four interconnected elements were considered: individual, society and community; disciplinary corpus; project production and evaluation. The results reveal the potential of these archaeological spaces in the territory and their impact on the environment. Opportunities are also identified to transform the surrounding environment, promoting the reactivation of these cultural vestiges and the development of sustainable communities in Lambayeque, Peru.

Search of Circular Surface Landforms with Negative Topography Associated with Geological Processes in a Physical Geography Framework within the Province of Pichincha, Ecuador.

Francisco Guerrero, Myrian Herrera, Milton Ramírez — Wed, 14 Aug 2024 00:00:00 -0400

The circular surface landforms with negative topography are the result of the interaction of factors of natural origin associated with active and inactive geological processes; therefore, if these processes occur again, they would generate events that may constitute a threat to the population, the means of production and the environment, making it necessary to identify, define and spatially locate these structures in the territory. This study is a first approximation of achieving this purpose through compositions of geometric signatures using the variables of slope, texture, convexity, concavity, valley depth, convergence index and analytical hillshading in the SAGA 7.8.2 software. The procedure carried out began with the recognition of circular landforms with positive topography as volcanic structures and their main characteristics (drains, slopes, craters, escarpments, erosion marks, among others), these already identified structures allowed us to collect useful information to define circular landforms with negative topography delimiting a large erosion zone in the northeastern study area. However, the need to determine an automatic procedure that allows the identification of target structures in an automated way, through the use of geographic information systems is confirmed.

Historical Structuring and Technological Evolution of the National Geodetic Network of Chile - Horizontal

Germán Aguilera — Wed, 14 Aug 2024 00:00:00 -0400

The Military Geographic Institute (IGM) was set up in accordance with the Decree Law N°1.664 of the 29th of August, 1922 and is currently the official technical and permanent service of the State, in all geographic matters, in compliance with the second point of Article N.° 2 of Law N.° 15284 of 1963. Among the most important of its tasks is the mission of providing a Reference Frame in accordance with the requirements of the international standards of each epoch, for the production of geo-referenced information. The National Geodesic Network (RGN in Spanish initials) has been the reference frame for all geodesic and cartographic activities and portrayals over time. It is made up of geodesic points set up at strategic locations across and along this territory, measured and calculated by this Institute; these have plane, geographic and altitude coordinate values. Currently, the horizontal component of the SIRGAS-Chile RGN consists of a set of Continuous Operation Reference Stations (CORS), providing daily GNSS data and official coordinates for the various uses of national development.

Chile, due to its special geographic situation, arising from its location and its long, narrow, and elongated territory has had to adopt, over time, various geodesic reference systems in accordance with the requirements of international organisations that support and promote geodesy. Moreover, since 1922, these reference systems have evolved due to substantial progress in technology, defining a RGN that is modern and precise at this time.

Urban Territorial Planning and Integrated Watershed Management in Comparative Perspective. The Mendoza (Argentina) and Aconcagua (Chile) Rivers.

Wed, 14 Aug 2024 00:00:00 -0400

Extreme weather phenomena (heat waves, forest fires, melting glaciers, rising sea levels, warmer and more acidic oceans, hurricanes, droughts and floods, etc.), which are changing and intensifying as a result of climate change, are seriously affecting the lives of people in both urban and rural areas. One of the most urgent problems to be solved is water scarcity. It has been demonstrated that part of this meteorological drought is due to human actions and that the water variable must be integrated into urban and land use planning.

The hypothesis of this research is that factors of different nature do not allow achieving territorial planning based on integrated watershed management, in the two investigated case studies: the Mendoza River Basin in Argentina and the Aconcagua River Basin in Chile.

The objective of this study was to analyze the regulatory, institutional, governance, sustainability, and climate change components that hinder integrated water resource management through a qualitative methodology. Both case studies reveal obstacles to achieving territorial planning based on integrated watershed management. The Chilean case presents even greater difficulties due to a regulatory and legal framework that still centers on private ownership of water.

Soil erosion risk in the Mocache canton applying Multicriteria Analysis and Geographic Information Systems

José Luis Muñoz Marcillo, Luis Veas Triana — Wed, 14 Aug 2024 00:00:00 -0400

Soil erosion is one of the main and most widespread types of soil degradation, determined by environmental and anthropogenic factors, which significantly impact the physical, chemical and biological properties of the soil, favoring its degradation. Consequently, through this research we sought to evaluate the risk of soil erosion in the canton of Mocache through the application of multicriteria analysis techniques and the use of geographic information systems (GIS). The CORINE model included several criteria for the zoning of potential and actual erosion risk, including erosivity, defined by the Modified Fournier Index (MFI) and the Bagnouls-Gaussen Aridity Index (BGI); erodibility, composed of soil texture, stoniness and depth; soil occupation; slope-orientation; and vegetation cover, through the estimation of the Normalized Difference Vegetation Index (NDVI). An expert consultation supported by Analytic Hierarchy Process (AHP) was applied to define the contribution of each criterion to erosion risk. The resulting layers were combined using a weighted relationship (map algebra) within the GIS environment. It was obtained that slope-orientation and erosivity explain a large part of the erosion risk, with a weighting of 42.46% and 27.48% in order, according to the expert evaluation and the AHP. The high erosivity was contributed by the predominant climatic factors: intense precipitation and high temperatures. In addition, it was found that the potential and current erosion risk represent 13.1% (7,244 ha) and 10.7% (5,905 ha) of the territorial extension. It is concluded that physical-natural, meteorological factors and anthropogenic activities contribute to the risk of potential and current soil erosion in Mocache canton.

A way for explaining Geo Big Data through its characteristics, sources, and central support technologies

Giancarlo Alciaturi, María del Pilar García - Rodríguez, Virginia Fernández — Wed, 14 Aug 2024 00:00:00 -0400

Big Data has significantly impacted scientific research and everyday life, resulting in solutions that align with its principles. Therefore, it is essential to propose ways that enable a basic understanding of specific fields of knowledge, such as those related to spatial domain information. Through a narrative review, this document explains the fundamentals of Geo Big Data by contextualising the characteristics, sources, and central technologies of Big Data in relation to geographic information. One of the most significant findings is that Geo Big Data helps enhance the understanding of biophysical and human dimensions of spatial matters. The technology boosts the acquisition of valuable insights and opportunities across various areas, including risk management, health, agriculture, environment, and open government. This document lays some groundwork for implementing Geo Big Data initiatives towards more specific efforts.

Pressure on Water Consumption by the Expansion of Fruit Crops in Melipilla, Metropolitan Region of Chile

Marco Peña, Benjamín Mallea — Wed, 14 Aug 2024 00:00:00 -0400

This study investigated the expansion of the surface of five fruit crop species between 2004 and 2020 and the magnitude of their water consumption, for three communes in the Province of Melipilla, Metropolitan Region of Chile. The statistical information about the crops was obtained from the fruit crop cadasters of the Region, and their spatial information was taken from the Rural Territorial Information System (SIT), while various sources of secondary information were used to approximate the water requirements of each species of interest. The results detail the cartography of expansion and increase in water consumption of the species on the dates of interest, which, in a context of mega-drought persisting since 2010, translates into a strong inverse correlation between consumption and water supply in the lower basin of the Maipo River. On the other hand, the magnitude of these water consumptions represents a significant proportion of water uses within the Maipo River basin, surpassing the combined uses of rural drinking water, forestry, livestock, and mining, and encompassing 22 % of urban drinking water consumption in the Metropolitan Region. As the relationship between availability and water deficit narrows, the absence of sustainable water management that could ensure water security within the country's most populous basin becomes palpable.

Assessment of a Downscaling Using Quantiles Mapping With MIROC Model in Guadalquivir Basin, Bolivia

Jhonatan Ureña, Oliver Saavedra — Wed, 14 Aug 2024 00:00:00 -0400

In this study historical and combined GS precipitation products were assessed versus climate change scenarios at Guadalquivir basin. The purpose of this study was to evaluate the downscaling procedure using Quantiles Downscaling Mapping (QDM). This scheme is based in statistical analysis where precipitation and temperature are adjusted using observed datasets. Moreover, simulated river discharge was obtained using HYDROBID tool. It was identified underestimation of combined GS precipitation product as well as simulated river discharge. Three climate change scenarios from MIROC CORDEX were used namely: RCP2.6, RCP4.5 and RCP8.5. The precipitation and temperature analyses were performed at daily time step. The results of QDM application showed more efficiency with RCP 8.5 and combined product GS for the 230 subbasins. About hydrological modeling using CORDEX variables, it was observed perturbed climate change using combined product GS with lower values against rain gauges. In this sense, precipitation and discharge were underestimated. Temperature showed the best performance at all cases. Finally, discharge series were integrated into volumes, where a decrease in water availability at the basins was noted as for near and far future. It is recommended to use perturbed scenarios with combined precipitation product since it is the most critical and takes into account the spatial variability with 230 syntactical rain gauges.

Proposal for the redesign of post COVID 19 cities in the labor field

Francisco Morales Peña, Ignacio Mesina, Cristóbal Peralta — Wed, 14 Aug 2024 00:00:00 -0400

This study focuses on the proposal to establish Intercommunal Work Centers (CTI) as a solution to reconfigure urban space in response to the COVID-19 pandemic. 34 communes of Greater Santiago are examined, grouped into 5 macrocommunes, with the objective of locating at least one CTI in each macrozone. A macro simulation methodology is used that weights socio-territorial variables, including socioeconomic level, level of study, employment, overcrowding and internet connection. The results offer a solid basis for optimal localization of CTIs based on these variables.

The Transformation of Chacabuco Village: From the Pre-Columbian to the Metropolitan Periphery of Santiago, Chile.

Gloria Naranjo , Martin Bécar, Pablo Venegas, María Díaz — Wed, 14 Aug 2024 00:00:00 -0400

The process of transformation of the Province of Chacabuco throughout its history according to historical, cartographic and testimonial background, constitutes the central objective in this writing. The facts that describe the process of territorial occupation and the different forms it has taken over time identifying five settlement impulses that are related to the structures that were formed in the territory, with the objective of understanding in detail the occupation of the territory and explaining the causes that impulse it. Since the 17th century, the territory of Chacabuco had scattered human settlements and a countryside organized under the hacienda system for agricultural and livestock use, with a small population around the houses, which after the appearance of the Santiago- Valparaíso railroad generated an agglomeration of dwellings around the stations. From the seventeenth century until the first half of the twentieth century, the territory lacked housing and was mainly devoted to livestock, agriculture or remained unused. However, in the second half of the 20th century, the settlement had an explosive development, linked to urban expansion processes of the city of Santiago, the main metropolis of the country.

The Antarctic Continent: a geostrategic interest of the Colombian State

Wed, 14 Aug 2024 00:00:00 -0400

The purpose of this research article is to determine the geostrategic relevance for the Colombian State, reflected in policies, research and institutional architecture that covers the Antarctic continent. The argumentation and analysis are supported by primary and secondary sources, which allow visualizing the characteristics, conditions, contributions and projection of Colombia in the Antarctic Treaty System. As a working hypothesis, Colombia has identified Antarctica as part of a geostrategic interest -from a humanistic and investigative perspective- and has deployed a series of institutional efforts in the last 30 years to approach the understanding of the region. As conclusions, there is a clear oceanic, aerial, cyberspace, space, climatic and biological connection between Colombia, represented in public institutions -such as the Foreign Ministry and the Military Forces- and educational institutions -such as universities and research centers- and the Antarctica, inserting it in this way as a geostrategic interest of the country

Editorial

Carlos Prado Casanova — Wed, 14 Aug 2024 00:00:00 -0400