Remote Sensing to Detect and Monitor Trees in Various Environments: Case Studies in Chile

Today, the presence of green areas in cities plays an important role for the well-being of its inhabitants and its sustainable development. Modern cities need green spaces for environmental, psychological, esthetic, economic, and social reasons. In this meaning, Chilean cities, although Chile is still considered by the United Nations1 as a developing economy, are no exception. Given the importance of this common good, it is necessary to optimize its permanent care. An incident factor in the deterioration of vegetation in urban and rural areas is stress, which can be of biotic or abiotic origin. One way to systematize care of trees is by the application of multispectral sensors and modern digital image processing. Once plantations or trees are spectrally characterized, one can proceed to develop plant health mitigation programs. This article shows the potential of remote sensing for tree stress detection, in the central south of Chile. Focus is given on rural areas as forestry for the Chilean economy is of great importance. These approaches can easily be adapted to urban scenarios

Climate Factors’ Effects on Glacier Variations in the Commune of Alto del Carmen, Chile

Ice bodies in the semi-arid mountainous regions of Chile are of vital importance for the local population. As variations of their extent are often associated with climate change, this study focuses on the glaciers and glacierets situated in the Commune Alto del Carmen and local and regional climate. We combine statistically Landsat satellite imagery, historical and ongoing weather data. The present study covers a time span of 21 years, 1994–2015. Our results indicate that the extent of all ice bodies has continuously diminished as a consequence of long-term climate variability

POTENCIAL DE LA PERCEPCIÓN REMOTA – ESTUDIO BASADO EN DESASTRES NATURALES OCURRIDOS DURANTE LOS ÚLTIMOS 5 AÑOS EN CHILE

A través de desastres naturales ocurridos en Chile durante los últimos 5 años se ejemplifica como observaciones adquiridas por los diversos sensores, hoy en día disponibles en la Percepción Remota, fueron utilizadas con éxito en varias ocasiones, tanto durante como después de que ha ocurrido una catástrofe. Los ejemplos presentados en el presente artículo están relacionados con el terremoto y posterior tsunami ocurrido en febrero 2010 y las erupciones volcánicas en los años 2008 y 2011. Se da a conocer las plataformas y los sensores remotos más convenientes para realizar una administración moderna de desastres naturales.Aunque el catastro de daños producidos por un desastre natural es la aplicación más conocida en público, la Percepción Remota también puede ser usada en todas las fases de su administración: Mitigación, Preparación, Respuesta y Recuperación. Por tal motivo también se muestra como y en que situación puede ser útil el uso de datosadquiridos por sensores remotos. Como la Percepción Remota puede serconsiderada como una de las más importantes herramientas en el ámbito de la administración de desastres naturales se concluye que en un país como Chile, su aplicación debe ser intensificado para poder superar cualquier catástrofe

Glacier Monitoring Based on Multi-Spectral and Multi-Temporal Satellite Data: A Case Study for Classification with Respect to Different Snow and Ice Types

Remote sensing techniques are frequently applied for the surveying of remote areas, where the use of conventional surveying techniques remains difficult and impracticable. In this paper, we focus on one of the remote glacier areas, namely the Tyndall Glacier area in the Southern Patagonian Icefield in Chile. Based on optical remote sensing data in the form of multi-spectral Sentinel-2 imagery, we analyze the extent of different snow and ice classes on the surface of the glacier by means of pixel-wise classification. Our study comprises three main steps: (1) Labeled Sentinel-2 compliant data are obtained from theoretical spectral reflectance curves, as there are no training data available for the investigated area; (2) Four different classification approaches are used and compared in their ability to identify the defined five snow and ice types, thereof two unsupervised approaches (k-means clustering and rule-based classification via snow and ice indices) and two supervised approaches (Linear Discriminant Analysis and Random Forest classifier); (3) We first focus on the pixel-wise classification of Sentinel-2 imagery, and we then use the best-performing approach for a multi-temporal analysis of the Tyndall Glacier area. While the achieved classification results reveal that all of the used classification approaches are suitable for detecting different snow and ice classes on the glacier surface, the multi-temporal analysis clearly reveals the seasonal development of the glacier. The change of snow and ice types on the glacier surface is evident, especially between the end of ablation season (April) and the end of accumulation season (September) in Southern Chile

Making the asphalt paving process explicit - A fundamental step for quality improvement

Cilj ovog rada je jasno definiranje postupka asfaltiranja kolnika i uz njega vezane podatke o temperaturi i zbijenosti asfalta te logističkog procesa, budući da je to temeljni preduvjet za postizanje poboljšanja. U tu svrhu, prikupljeni su podatci o temperaturi asfalta, putanjama kretanja valjaka, zbijenosti asfalta, brzini kretanja finišera te o logističkoj podršci kamionima koji dopremaju asfalt. Rezultati, analize i dobivene povratne informacije upućuju na postojanje konkretnih mogućnosti za poboljšanje, koje uključuju izbjegavanje zaustavljanja finišera tijekom asfaltiranja, ujednačeno zbijanje cijele površine kolnika te izrada strategije za kretanja valjaka.The objective of the paper is to make explicit the paving operations, the related asphalt temperature and density data, and the logistic process, as a fundamental step to identify improvement opportunities. For that, temperature data, roller compactor trajectories, asphalt density, paver speed, and trucks logistics, were collected. The results, analysis, and feedback received, point to specific opportunities for improvement, including avoiding the paver start-stop cycles, uniform compaction of the entire pavement surface, and definition of roller compaction strategy

Potencial de la percepción remota - estudio basado en desastres naturales ocurridos durante los últimos 5 años en Chile

A través de desastres naturales ocurridos en Chile durante los últimos 5 años se ejemplifica como observaciones adquiridas por los diversos sensores, hoy en día disponibles en la Percepción Remota, fueron utilizadas con éxito en varias ocasiones, tanto durante como después de que ha ocurrido una catástrofe. Los ejemplos presentados en el presente artículo están relacionados con el terremoto y posterior tsunami ocurrido en febrero 2010 y las erupciones volcánicas en los años 2008 y 2011. Se da a conocer las plataformas y los sensores remotos más convenientes para realizar una administración moderna de desastres naturales. Aunque el catastro de daños producidos por un desastre natural es la aplicación más conocida en público, la Percepción Remota también puede ser usada en todas las fases de su administración: Mitigación, Preparación, Respuesta y Recuperación. Por tal motivo también se muestra como y en que situación puede ser útil el uso de datos adquiridos por sensores remotos. Como la Percepción Remota puede ser considerada como una de las más importantes herramientas en el ámbito de la administración de desastres naturales se concluye que en un país como Chile, su aplicación debe ser intensificado para poder superar cualquier catástrofe

MONITORING GROUNDWATER STORAGE IN NORTHERN CHILE BASED ON SATELLITE OBSERVATIONS AND DATA SIMULATION

Groundwater is one of the most valuable sources of fresh water in many places worldwide, especially in regions with low pluviometric indices such as northern Chile. Thus, it is mandatory to monitor this precious resource in space and time domains. Currently, groundwater in Chile is monitored using sparse stations of water table observations. Although other indirect alternatives such as space-borne observations can contribute to regional understanding of groundwater variations, they have been poorly studied in Chile. In this study, groundwater monitoring is carried out based on 104 monthly solutions of the Gravity Recovery and Climate Experiment (GRACE) mission between 2004 and 2013. The extraction of the groundwater storage (GWS) signal obtained from GRACE was recovered once the effects of soil moisture and snow storage, retrieved from the Global Land Data Assimilation System (GLDAS), were removed. Analysis of the data was performed point-wise (six stations) and at regional scale (Northern Chile). Overall, the results are correlated with wells observations obtained by the General Directorate of Water Resources (DGA) of the Ministry of Public Works of Chile. Point-wise comparison shows root mean square error (RMSE) large than 30.0 mm while regional scale validation shows RMSE of 21.5 mm. Furthermore, regional groundwater variations obtained from GRACE/GLDAS are highly consistent in terms of trend with results obtained from well observations in the DGA network. The Empirical Orthogonal Function (EOF) analysis revealed higher annual groundwater variability in the metropolitan region and a higher inter-annual variability in the north. The methodology used may contribute to the regional study of spatial-temporal variations of groundwater in regions with sparse hydrometric networ