Vulnerability is defined by the socioeconomic conditions prior to the occurrence of a catastrophic event. The eruption of Cordón Caulle in June 2011 brought consequences to the Nahuel Huapi region, mainly in Villa La Angostura. Economic activities, basic services, transport and communication systems, among others, were all affected by the ash fall. The objective of this paper is to develop a methodological tool to assess the social vulnerability to the fall of volcanic ash from the indicators provided by the 2010 National Household and Housing Population Census which shows the scenario prior to the eruption. At the same time, it facilitates its replicability based on data available at the national level. The indicators were mapped, analyzed by census radios and collated with available information on the measures adopted during the emergency so that a final vulnerability map was drawn up. The opportunity and relevance of census data to anticipate vulnerable sites was highlighted especially when considering the housing conditions, drinking water supply system and the materials and roof’s slope, as well as the improvements made after the emergency (e.g. drinking water supply and distribution systems).

La vulnerabilidad está definida por las condiciones socioeconómicas previas a la ocurrencia de un evento catastrófico. La erupción del Cordón Caulle iniciada en junio de 2011 trajo consecuencias a la región del Nahuel Huapi, principalmente Villa La Angostura, en actividades económicas, servicios básicos, transportes y comunicaciones, entre otras. El objetivo del trabajo es desarrollar una herramienta metodológica para evaluar la vulnerabilidad social frente a la caída de ceniza volcánica a partir de indicadores provistos por el Censo Nacional de Población, Hogares y Viviendas realizado en el año 2010, que muestra el escenario previo a dicha erupción, a la vez que facilita su replicabilidad a partir de datos disponibles a nivel nacional. Los indicadores fueron mapeados, analizados por radios censales y se cotejaron con información disponible sobre las medidas adoptadas durante la emergencia y se elaboró un mapa final de vulnerabilidad. Se destacó la oportunidad y pertinencia que presentan los datos censales para anticipar sitios vulnerables, especialmente cuando se consideran las condiciones habitacionales, el abastecimiento de agua potable y los materiales e inclinación de los techos, así como también las mejoras realizadas luego de la emergencia, por ejemplo, en el sistema de abastecimiento y distribución del agua de red.

Este trabalho analisa a turbidez e a circulação da agua no canal San Blas durante um ciclo de maré teórico através de imagens satelitais. Foram utilizadas 8 imagens Landsat TM e ETM adquiridas em condições de céu claro e ao longo de diferentes momentos da maré. As imagens foram proporcionadas pela Comisión Nacional de Actividades Espaciales (CONAE) y pelo Serviço Geológico dos Estados Unidos (USGS). As correções geométricas e radiométricas foram realizadas nas bandas do espectro visível e do infravermelho próximo, utilizando técnicas padrões de processamento digital. Foi aplicada a correção atmosférica COST (CHAVEZ, 1996). Foi realizada uma classificação ISODATA não supervisionada para identificar diferentes níveis de turbidez al longo do canal e zonas adjacentes. Os resultados sugerem que o transporte de sedimento em suspensão para a boca do canal se da ao longo de ambos flancos, pela ação das correntes de refluxo. Estas correntes geram um delta de refluxo com uma tendência de rotação para a direção sul. As correntes de fluxo provocam turbidez principalmente sobre a costa sul do canal, gerando um delta de fluxo com bancos alargados na direção das correntes de maré. As plumas de turbidez permitiram identificar padrões gerais de circulação da maré.

This paper deals with the application of satellite images to study turbidity and water circulation patterns in San Blas channel during a theoretical tidal cycle. Eight Landsat TM and ETM images acquired under clear-sky conditions and representing different tidal stages were selected from a pool of Landsat images provided by the argentinean National Commission of Space Activities (CONAE) and the US Geological Survey. Standard digital image processing techniques were used to perform geometric and radiometric corrections on the visible and near-infrared bands. An image-based atmospheric correction (COST method by CHAVEZ, 1996) was applied. An ISODATA unsupervised classification was performed in order to identify different turbidity levels throughout the channel and adjacent areas. The results suggest that suspended sediment transport towards the channel mouth by ebb currents occurs along both flanks. These currents carry suspended sediment into the open sea, generating an ebb tidal delta which tends to rotate in a clockwise direction. Flood currents trigger turbidity mostly over the southern flank of the channel, generating a flood tidal delta with elongated banks extending in the direction of the tidal currents. From the elongated shape of the turbidity plumes, general tidal circulation patterns were identified.

Some interaction processes at the sediment-water and sediment-atmosphere interfaces were analyzed for each season of the year using mass aerodynamic formulas. Data were collected from Puerto Cuatreros tidal flats (Bahía Blanca estuary, Argentina) during an entire year (2000). The soil temperature was measured every 10 min by a thermistor chain at three levels below the sediment surface (-0.05, -0.15 and -0.25 m). Water and air temperatures, solar radiation and meteorological data were registered simultaneously, resulting in annual means of 14.07°C (soil at -0.15 m), 13.69°C (air) and 14.51°C (water). Atmospheric and tidal conditions regulated the mudflat's thermal behavior. The soil temperature vertical profiles showed a diurnal and semidiurnal cycle due to the influence of these factors. The diurnal thermal amplitude at -0.05 m reached 14.6°C on 20 February 2000, but only 2.8°C on 1 July 2000. Most fluctuations of sediment temperatures were observed in the first 15 cm, with vertical gradients of 0.82°C cm-1 during summer. In order to obtain the soil heat capacity, the granulometric composition of a sediment column was analyzed. Soil heat fluxes during a typical summer and winter day were compared. A net heat gain in the soil was observed during the summer day (+840.6 kJ m-2) and an inverse situation was found in winter, with a diurnal heat exchange of-768.6 kJm-2.

Se analizaron procesos de interacción sedimento-agua y sedimento-atmósfera para cada estación del año mediante fórmulas aerodinámicas de masa. Los datos fueron recolectados en la llanura intermareal de Puerto Cuatreros (estuario de Bahía Blanca) durante un período anual (2000). La temperatura del suelo se midió cada 10 min empleando una cadena de termistores localizados a tres niveles de profundidad: -0.05, -0.15 y -0.25 m. Simultáneamente, se registraron las temperaturas del agua y del aire, la radiación solar y datos meteorológicos. Los valores medios anuales fueron 14.07°C, 13.69°C y 14.51°C para sedimento a -0.15 m, aire y agua, respectivamente. La radiación solar y las mareas regularon el comportamiento térmico de la planicie de marea. Debido a la influencia de estos factores los perfiles verticales de temperatura del sedimento mostraron un ciclo diurno y semidiurno. La amplitud térmica diurna a -0.05 m alcanzó los 14.6°C el 20 de febrero, mientras que durante el Iº de julio Se observaron sólo 2.8°C de amplitud. Las mayores fluctuaciones en la temperatura del sedimento se registraron en los primeros 15 cm, desarrollándose gradientes verticales que alcanzaron los 0.82°C cm-1 durante el verano. A fin de obtener la capacidad calorífica del suelo en estudio se analizó la granulometría de una columna de sedimentos. Se comparó el flujo de calor en el suelo durante un día típico de verano y uno de invierno evidenciándose una ganancia neta de calor durante la jornada estival (+840.6 kJm-2) y una situación inversa en el invierno (-768.6 kJm-2).