Abstract Given the frequent spatial-temporal limitations and deficiencies of instrumental meteorological records, the use of alternative information sources, such as integrated databases, are important for analyses and studies of diverse nature. The research aim was to evaluate the accuracy of integrated databases of monthly temperature, belonging to Climate Research Unit, University of Delaware and Global Historical Climatology Network, gridded with a pixel size of 3,098.01 km2 (0.5º x 0.5º), surface area of 151,802.5 km2 and temporary length of 22 years (1993-2014), through the modified structural similarity index (mSSIM). The study area is located in central-western Argentina (between 30º and 35º S, and 71º and 66º W). The University of Delaware grid showed the best fit of the data series from 10 weather stations located in the study area. Therefore, a proposal was presented to increase similarity indices, especially for those cells without instrumental reference information. The study determined that by applying this modification, the gridded datasets increases the similarity of the measured data, especially in mountainous areas, where originally there were differences of more than 7.5 ºC between the gridded data and observed one. The proposal decreases these differences to average values below 1 ºC. The use and subsequent adjustment of these integrated databases, allows access to information in areas without meteorological records.

Resumen Dadas las limitaciones y carencias espaciotemporales de los registros meteorológicos instrumentales, el uso de fuentes de información alterna, como las bases de datos climáticas integradas, resultan de gran importancia para análisis y estudios de diversas índoles. El objetivo de la investigación fue evaluar la precisión de las bases de datos integradas de temperatura mensual de la Climate Research Unit, University of Delaware y del Global Historical Climatology Network, organizados en grillas con pixel de 3 098.01 km2 (0.5º x 0.5º), extensión superficial de 151 802.5 km2 y longitud temporal de 22 años (1993-2014), a través del índice modificado de similitud estructural (mSSIM). La zona de estudio se localiza en el centrooccidente argentino (entre los 30º y 35º S, y los 71º y 66º O). La grilla de la University of Delaware mostró el mejor ajuste de las series de datos de 10 estaciones meteorológicas localizadas en el área de estudio. Por tanto, se presenta una propuesta para elevar los índices de similitud, en especial para aquellas celdas sin información instrumental de referencia. El estudio permitió determinar que, aplicando dicha modificación, la base de datos grillada aumenta la similitud de los datos medidos, sobre todo en áreas montañosas, donde originalmente se encontraban diferencias de más de 7.5 ºC entre el dato grillado y el observado. La propuesta disminuye esas diferencias a valores promedios inferiores a 1 ºC. El uso y posterior ajuste de estas bases de datos integradas, permite acceder a información en zonas sin registros meteorológicos.

El conocimiento de la respuesta hidrológica de las lagunas urbanas subtropicales ante distintos eventos de sequías o inundaciones es esencial para orientar las políticas de ordenamiento del espacio urbano de manera sustentable. La provincia de Corrientes (Argentina) presenta un paisaje caracterizado por numerosas lagunas subtropicales en las que en sus márgenes se construyen estructuras urbanas. En este contexto, el estudio de la variabilidad pluviométrica, junto con sus efectos sobre estos cuerpos de agua es crucial para generar un sistema de alerta temprana con la finalidad de reducir los riesgos de inundación. Por ello, el objetivo de este estudio fue analizar la variabilidad pluviométrica de Corrientes y los cambios morfométricos de las lagunas y charcas subtropicales ante eventos extremos de sequías, inundaciones y eventos pluviométricos normales. Para ello, se analizaron series históricas de precipitación para el período 1962-2018, proporcionadas por el Servicio Meteorológico Nacional (Argentina). Utilizando métodos de la normal, de quintiles y el Índice Estandarizado de Precipitación se estudiaron los eventos secos, húmedos y normales. Posteriormente, con el análisis de imágenes satelitales Landsat y de Google Earth se estudió la evolución de las áreas construidas, durante eventos secos y su impacto ante eventos lluviosos. Los resultados demostraron que estos cuerpos de agua periurbanos presentan una relación con los eventos pluviométricos y responden inmediatamente a la variabilidad climática local, exponiendo los frentes de avance de la ciudad en áreas periurbanas a ocupar espacios correspondientes a lagunas. Las mismas pueden reducir su tamaño e incluso secarse, aun cuando se presenten años extremos de inundación.

O conhecimento da resposta hidrológica de lagoas urbanas subtropicais a diferentes eventos de seca ou inundação é essencial para orientar as políticas sustentáveis de gestão do espaço urbano. A província de Corrientes (Argentina) apresenta uma paisagem caracterizada pela localização de inúmeras lagoas subtropicais nas margens das quais se constroem estruturas urbanas. Neste contexto, o estudo da variabilidade das chuvas, juntamente com os seus efeitos sobre esses corpos de água, é crucial para gerar um sistema de alerta precoce, a fim de reduzir os riscos de inundação. Portanto, o objetivo deste estudo foi analisar a variabilidade das chuvas de Corrientes e as mudanças morfométricas das lagoas e charcos subtropicais em caso de eventos extremos de seca, inundações e eventos normais de chuva. Para isso, foram analisadas séries históricas de precipitação para o período de 1962 a 2018, fornecidas pelo Serviço Nacional de Meteorologia (Argentina), e foram aplicados os métodos normal, quintil e Índice de Precipitação Padronizado para analisar eventos secos, húmidos e normais. Posteriormente, com a análise das imagens de satélite Landsat e Google Earth, foi estudada a evolução das áreas construídas durante eventos secos e seu impacto em eventos chuvosos. Os resultados mostraram que esses corpos de água periurbanos apresentaram uma estreita relação com os eventos pluviométricos, respondendo imediatamente à variabilidade climática local e expondo as frentes da cidade em áreas periurbanas a ocupar espaços correspondentes a lagoas. As mesmas podem reduzir o seu tamanho ou secar, mesmo em anos extremos de inundação.

La connaissance de la réponse hydrologique des lacs urbains subtropicaux aux différents épisodes de sécheresse ou d’inondation est essentielle pour guider de manière durable les politiques de gestion de l’espace urbain. La province de Corrientes (Argentine) présente un paysage caractérisé par l’emplacement de nombreuses lagunes subtropicales dans lesquelles les rivages sont construits. Dans ce contexte, l’étude de la variabilité des précipitations, ainsi que de ses effets sur ces masses d’eau, est essentiel pour générer un système d’alerte précoce afin de réduire les risques d’inondation. Par conséquent, l’objectif de cette étude était d’analyser la variabilité des précipitations à Corrientes et les changements morphométriques des lagunes et des étangs subtropicaux en cas de sécheresse extrême, d’inondation et de pluie normale. Pour cela, des séries historiques de précipitations ont été analysées pour la période 1962-2018, fournies par le Service Météorologique National (Argentine). La loi normale, les quintiles et l´index Normalisé de Précipitations ont été appliqués pour analyser les événements secs, humides et normaux. Par la suite, avec l’analyse des images satellites Landsat et Google Earth, l’évolution des zones bâties a été étudiée lors des événements secs, ainsi que leur impact sur les événements pluvieux. Les résultats ont montré que ces masses d’eau périurbaines présentaient une relation étroite avec les événements pluvieux, répondant immédiatement à la variabilité climatique locale et exposant les fronts de la ville dans les zones périurbaines à occuper des espaces correspondant à des lagunes qui peuvent réduire leur taille ou bien peuvent sécher, même dans les années extrêmes d’inondation.

Knowing the hydrological response of subtropical urban shallow lakes subjected to drought or flood events is essential to guide sustainable urban space management policies. The province of Corrientes (Argentina) presents a landscape characterized by numerous subtropical shallow lakes in which urban structures are built on its edges. In this context, the study of rainfall variability and its effects on these water bodies is crucial to generate an early warning system to reduce the risk of flood. In this sense, this study aims to analyse the rainfall variability of Corrientes as well as the morphometric changes in the shallow lakes and ponds during normal rainfall events and extreme events such as floods and droughts. Meteorological data from the period 1962-2018 were analysed applying normal, quintiles methods and a standardized precipitation index. Dry and wet events were identified and subsequently, satellite images were studied to measure the building area. Results demonstrate that the peri-urban shallow lakes have a relationship with the pluviometrical events and they vary immediately in line with local climate conditions, exposing the areas of these lakes to be replaced by urban buildings. These water bodies change their size and even dry out, although there are extreme events of flooding.

Abstract Current and future studies on precipitation are essential for designing space-planning policies, being particularly relevant in semi-arid regions. The south of the Pampas region is an agricultural area where rainfed crops occupy the largest area. This area, located in a transition zone between temperate and semi-arid climates, is characterized by the occurrence of the most severe and lasting extreme events of the whole region. Therefore, knowledge of their current and future seasonal and annual rainfall regimes, along with their spatial-temporal changes, is essential to ensure the economic and environmental sustainability of this area. In this context, this study analyzed rainfall variability in six periods defined as recent past (1977-1997), present (1998-2018), near future (2019-2039), and distant future (2079-2099). The latter two were identified considering two greenhouse gas (GHG) concentration scenarios. We worked with on-site data from six weather stations and those from the Community Climate System Model version 4 (CCSM4) climate model. In a first instance, the period 1960-2010 was analyzed to evaluate whether both data sources were statistically equivalent. To this end, mean values and standard deviations were calculated, followed by Fisher and KolmogorovSmirnov tests. After demonstrating that the datasets were statistically homogeneous, the annual, seasonal, and spatial patterns of each weather station were compared for the periods previously defined. We analyzed the mean values, homogeneity, trends, and spatial behavior. The trend was evaluated using the Mann-Kendall test, and the time series were analyzed with an empirical probability study. In addition, the spatial-temporal variation was explored applying the Kriging interpolation method. The study area showed significant changes between the periods considered. These included changes in mean values. For example, the north showed four periods with different precipitation levels, while only three were observed in the south. In all cases, we found a highly significant statistical significance (Fisher’s statistic < 0.001), considering an α of 5 %. For its part, the analysis of trends showed an increase of annual precipitation in the distant future in the north. At Coronel Suárez (north), for example, annual precipitation figures were 864 and 1093 mm for the present and the distant future, respectively. However, the south of the study area showed a ≅ 50 mm decrease, but with an increase in the frequency of rainy years. This was evident, for example, in the Hilario Ascasobi station, showing a decreasing trend with annual precipitation figures ranging from 520 mm in the past to 442 mm in the distant future (GHG concentration of 4.5). The region showed a marked seasonality in future precipitation estimates. The highest amounts occur during summer and spring, being intermediate in autumn and lowest in winter. This same pattern was observed across most of the study area, except for Hilario Ascasobi (located to the south), where summer was the season with the lowest precipitation levels in the past and present. However, the seasonal pattern in the near and distant future was similar to the pattern in the rest of the study area. Autumn was the only season when precipitation increased in the south of the study area (≅ 30 mm). The importance of assessing past, present, and future changes in precipitation lies in their direct relationship with productive activities in the study area. The inter-annual and seasonal variability of precipitation given the different growth stages of rainfed crops, while exposing the population to flood and drought risks, thus affecting their access to the resource. Therefore, these results will set the grounds for public and private decision-making social stakeholders to have a useful tool for sustainable land-use management.

Resumen El estudio actual y futuro de la precipitación es fundamental para diseñar políticas orientadas a planificar el espacio y adquiere mayor importancia en las regiones semiáridas. El sur de la Región Pampeana es un área agrícola donde los cultivos de secano ocupan la mayor extensión. Por lo tanto, el conocimiento de sus regímenes pluviométricos anuales y estacionales junto con sus cambios espacio-temporales es de vital importancia para garantizar su sustentabilidad económica y ambiental. En este contexto, el objetivo de este estudio fue analizar la variabilidad pluviométrica en el pasado reciente, el presente, el futuro cercano y el lejano en distintos escenarios de concentración de gases de efecto invernadero. Para ello, se trabajó con datos in situ y el modelo climático CCSM4. Se analizó el período 1960-2010 para evaluar si ambas fuentes de datos son estadísticamente iguales. Se compararón el patrón anual, estacional y espacial de las series de precipitación correspondientes a los períodos 1977-1997, 1998-2018, 2019-2039 y 2079-2099. Los resultados demostraron que en el norte del área de estudio se incrementan los montos anuales de precipitación hasta en 200 mm anuales en el futuro lejano, mientras que en el sur se observó una disminución de ≅ 50 mm, pero con un aumento de la frecuencia de los años lluviosos. El análisis de las isohietas evidenció la misma tendencia, destacándose el otoño como la única estación del año en la que se observó un incremento de las precipitaciones en el sur de la zona estudiada. Los resultados servirán de base para que los actores sociales con poder de decisión tanto públicos como privados dispongan de una herramienta útil para generar un ordenamiento sustentable del territorio.

Abstract Complete time series with no missing values are essential for reliable scientific-geographic analyses. Temperature time series commonly show data gaps, particularly in meteorological stations located in regions with few scattered stations. Scarce meteorological stations exist in the arid central-western region of Argentina, where vast, sparsely populated, or unproductive areas far away from major urban centers and oases may have restrained the installation of sufficient stations. Thus, climate data records from existing stations, especially those in rural areas, often lack temporal continuity, and the data gaps have to be filled in based on data from adjacent stations. However, this is not possible in the absence of nearby stations with reliable and sufficiently long records that can be used for estimating the missing data. This study aimed to develop an easy-to-apply, highly accurate operational method to fill data gaps in monthly temperature time series, which is particularly suitable for locations with no nearby meteorological stations. The method developed herein is based on the use of annual and monthly means and the overall time series average. The method was tested on the 46-yr time series of monthly temperature data recorded at the meteorological station of San Juan Aero (base station), located in the Province of San Juan, central-western Argentina. The base station is close to two other weather stations whose data were used to validate the results of one of the phases of the method. The study included: a) the application of the method proposed to the San Juan Aero station (base station) using subsets of varying lengths of the entire time series data set, and comparing the accuracy of the estimates thus obtained by means of ad hoc indices; b) the application of the same procedure used in a), but with varying percentages of missing data; c) the comparison of the missing values estimated by the method developed herein versus those estimated using conventional methods based on data from adjacent stations, and d) the application of the method developed herein to a meteorological station located outside the study area under different climate and environmental conditions. The method proposed (Ti) estimates missing monthly temperature values as the product of the average of the mean annual temperatures of the years immediately before and after the year with missing monthly data multiplied by the mean temperature of the target month, divided by twice the mean annual temperature of the data series. The method was used to estimate missing monthly temperature values for the 46-yr time series recorded in the San Juan Aero station. Tests were run to determine the percentage of missing data (5%, 10%, and 15%) with which the method yields the best fit. The efficiency of the Ti method was compared versus three traditional methods (arithmetic mean, normal proportion, and inverse distance weighting) that impute the missing values from data recorded at nearby stations. Finally, based on the results from the previous stages, the Ti method was applied to a test station located some 150 km from the baseline station to determine whether it can also be applied to meteorological stations located outside the study region, under different physical environmental characteristics. The results showed that the Ti method works better on meteorological stations having at least 30-yr records and no more than 10% missing data; under these conditions, its estimates are more accurate that those yielded by the three traditional methods tested and can be reliably applied to stations located outside the study region under different physical and environmental conditions. The limitations of the Ti method are worth mentioning: it cannot be used when the baseline station records have a data gap longer than one full year, or when data for the same month are missing for two consecutive years. Given the results yielded by this method and taking into account the limitations mentioned above, compared to other methods that use data from nearby stations, we recommend using the Ti method to estimate missing monthly temperature values for meteorological stations lacking nearby stations. Compared to the traditional methods tested, the Ti method seems highly valuable as a tool to fill missing data in temperature time series from isolated weather stations, which then could be used for climate analyses of remote zones.

Resumen El uso de series temporales sin valores faltantes resulta fundamental para la veracidad de los análisis científico-geográficos. Dado que en el caso de la temperatura (variable objeto de estudio), es posible encontrar vacíos de información en sitios con escasas estaciones meteorológicas, el objetivo de investigación fue desarrollar una metodología para completar series de tiempo mensuales cuando no se dispone de estaciones meteorológicas adyacentes. El método planteado se vincula al uso de temperaturas anuales, medias mensuales y promedio seriales, de modo que su proporción permita calcular los datos carentes de información. Tomando como base una estación meteorológica localizada al centrooccidente árido argentino, la investigación se centró en cuatro fases vinculadas a la aplicación de la propuesta. Inicialmente, se aplicó la metodología planteada para calcular valores faltantes mensuales sobre la estación San Juan Aero, con N= 46 años. Adicionalmente, se comparó la propuesta con otras metodologías que utilizan estaciones adyacentes y su aplicación sobre otra estación fuera del área de estudio. Todo lo anterior fue verificado mediante nueve índices de precisión. Los resultados indican que la metodología propuesta presenta óptimos resultados en estaciones con N ≥ 30 años, 10 % de datos faltantes y con precisión superior a otras metodologías de naturaleza similar. Se utilizó el método propuesto en series de tiempo pertenecientes a estaciones fuera del área de estudio y los resultados mostraron una alta fiabilidad en el cálculo de datos faltantes. Por lo tanto, se recomienda su uso para completar series temporales de temperaturas mensuales en estaciones sin pares adyacentes.

Resumen El estudio de los índices de confort es importante pues brindan información necesaria para orientar las políticas públicas destinadas al ordenamiento del espacio urbano, al igual que al ordenamiento y planificación de las actividades al aire libre. En este contexto, se estudió de forma estacional (verano e invierno), mensual y diaria el confort climático en Bahía Blanca (Argentina). Se localizaron diez estaciones de monitoreo de temperatura del aire y humedad relativa en distintos barrios de la ciudad, los cuales registraron datos de alta frecuencia. Con esa información, se calcularon los índices Humidex, Termo-anemométrico y Termo-higrométrico para caracterizar el confort estival, y el de Temperatura equivalente para el invierno. Los resultados permitieron delimitar las áreas más confortables de la ciudad de acuerdo con la cantidad de días con confort térmico, así como aquellas de desconfort con temperaturas inferiores a o°C. Se establecieron tres áreas urbanas diferenciadas que se agruparon según las condiciones similares de confort.

Abstract The study of comfort is relevant because provides information to generate urban planning policies. In this context, climate comfort was studied in Bahia Blanca city, Argentina applying different time-scales: seasonal (summer and winter), monthly and daily. Ten meteorological stations that registered temperature and relative humidity information in high frequency were located in diverse neighborhoods. Humidex, thermo-anemometric and thermo-hygrometric indexes were calculated to characterize the summer comfort as well as equivalent temperature for the winter. The results permitted to identify different areas according to the discomfort and comfort conditions during the summer and winter considering the number of days with temperatures below o°C. Three urban areas were delimited considering similar comfort conditions. The study could be relevant to the design of public policies in order to prevent negative effects of extreme thermal event on the inhabitants.

Resumo O estudo dos índices de conforto é importante porque eles fornecem as informações necessárias para os planos do espaço urbano de gestão. Neste contexto, estudamos sazonal (verão e inverno), mensal e diariamente el conforto em Bahia Blanca (Argentina). Em diferentes bairros foram localizados estações da monitorização da temperatura e umidade relativa registrados dados de alta freqüência. Humidex, Thermo-anemómetro termo-higrométrica foram calculados para caracterizar o verão equivalente conforto e temperatura durante o inverno. Os resultados ajudou a determinar as áreas mais confortável da cidade de acordo com o número de dias com conforto térmico, bem como as áreas de desconforto, com temperaturas abaixo de o°C. Tres diferentes áreas urbanas foram agrupados por condições de conforto semelhantes foram estabelecidos. Este estudo poderia ajudar a orientar as políticas públicas para organizar actividades ao ar livre.

The aim of this work was to characterize the climate variability of the northern coast of Bahia Blanca estuary (Argentina) in order to develop land use policies to improve the quality of life of the inhabitants. Climatic data in different time-scales for the 1960-2014 period was analyzed. Likewise, the Fast Fourier Transform, the Standardized Precipitation Index and standard statistical techniques were applied. As a result, the air temperature increased 0.9 °C, the relative humidity and rainfall presented wet and dry periods related to El Niño and La Niña events respectively. Maximum wind direction decreased 7.5 km h-1 in the 1986-2010 period. Finally, the effects of the climate variability in the region allowed outlining the guidelines for a sustainable land management plan.

El objetivo de este trabajo fue caracterizar la variabilidad climática temporal de la costa norte del estuario de Bahía Blanca (Argentina) para orientar las políticas de ordenamiento territorial destinadas a mejorar la calidad de vida de la población. Para ello, se analizaron datos climáticos en distintas escalas temporales para el período 1960-2014. Se aplicó una Transformada Rápida de Fourier, el Índice Estandarizado de Precipitación y técnicas estadísticas estándar. Como resultado se obtuvo que la temperatura media del aire se incrementó 0,9 °C, la humedad relativa y las precipitaciones presentaron ciclos húmedos y secos relacionados con la ocurrencia de eventos El Niño y La Niña, respectivamente y la velocidad media máxima del viento se redujo 7,5 km h-1 durante el período 1986-2010. Las consecuencias de la variabilidad climática sobre la región permitieron establecer las bases para la formulación de un plan de manejo sustentable del territorio.

Excessive anthropic occupation reduces the coastal extension and causes significant impacts on the ecosystem. Urban evolution in coastal areas has reached a point of no return. For this reason, the knowledge about whether a particular type of infrastructure or vegetation on a frontal dune could cause greater or lesser impact on the beach is extremely useful for urban planning. The study area was Pehuen Co (Fig. 1), a town located in the southwest of the Buenos Aires Province (Argentina). The aim of this work is to analyze the evolution of beach profiles backed with different foredune cover in order to understand the erosion/accretion processes that may be related to the various dynamic conditions. This will provide useful information to decision makers for urban planning and sustainable management projects orientated for short, medium and long terms. Pehuen Co is a dissipative beach with east-west coastal orientation within a region with alternating wet and dry periods. Normally, rains are concentrated in spring-summer, decreasing in autumn and becoming minimal in winter. The prevailing winds are from N and NW, with greater intensity in the spring and summer, mainly December and January. The study area coincides with the smaller beach of the downtown sector (Fig. 2). To the west, the foredune has been heavily eroded and has a steep front, whereas to the east there are vegetated, large dunes. The dominant vegetation is Tamarix gallica and Carpobrotus edulis, which are not observed in the walkways to the beach or where there are infrastructures over the foredunes. Beach profiles in different geomorphological situations were analyzed in order to describe their behavior. Three different sectors separated 50 m from each other were selected: ZC1 next to a restaurant on top of the frontal dune, ZC2 on the vegetated dune, and ZC3 on a walkway to the beach (Fig. 2). Monthly beach profiles were carried out from July 2007 to June 2010. The profiles were made using a modified version of the method proposed by Emery (1961), already developed in Bustos et al. (2013). The analysis of the beach profiles was performed seasonally (summer, autumn, winter and spring). Additionally, others were surveyed after strong storms. The profiles were digitalized and the volumes for the sediment budget and the Annual Variation Rate (AVR) were calculated. The volume was calculated considering a constant beach width equal to 1 m and a length defined by the shorter profile. Principal Component Analysis (PCA) was applied to complete the analysis of the seasonal beach profiles. The study for all sectors demonstrated that during winter periods they all present concave profiles (Fig. 3), while during the summer periods were characterized by significant berms (Table 1). The profiles at ZC1 and ZC2 behaved rather similarly, whereas those at ZC3 were still more concave than the others. ZC3 during the winter of 2009 presented a 1.5 m microcliff on the dune front. Also, during the summer profiles showed areas of accumulation, mainly with the formation of berms and bars (Fig. 3). The sedimentary balance reflected the behavior of the profiles, with volume increment in the summer periods and reduction in winter (Fig. 4). ZC1 presented a negative balance with an erosional trend. ZC3 profiles had the highest losses, with up to 60 m³ of erosion in the winter of 2008. The TVA for both profiles were negative, for ZC1 it was -12.9 m³/ yr, and for ZC3 of -20.3 m³/yr. In contrast, ZC2 had a positive TVA (9.9 m³/yr). Its largest gain occurred in Autumn 2009 (65.6 m³) (Fig. 4). ZC3 showed more concave profiles than the rest and represents the place with higher sediment loss, especially during rainfall. The entrances to the beach are constructed perpendicularly to the coast and without vegetation protection. For this reason, they are easily eroded, mainly by rainwater runoff. Monthly characteristics and trends in the behavior of the beach profiles were obtained by applying a PCA. The average profile of ZC1 presented a stable line with a slight concave tendency. Sediment loss was mainly observed in summer, winter and autumn; accretion occurred in spring (Fig. 5). The ZC2 profile showed a slightly concave shape, similar to ZC1, while small erosion cycles were observed every three months. The average profile showed losses in winter, spring and autumn, whereas it only gained sediment in summer (Fig. 6). The average profile in ZC3 is more concave than ZC1 and ZC2. The temporal components showed an erosion trend, with cycles of approximately six months of accretion-erosion. During autumn, winter and spring the sediment of the average profile decreased while increased in the summer (Fig. 7). In order to evaluate the damages and response of the beach profiles to erosive events, the impact of a wind storm that occurred between 22 and 23 July is presented as an example. This event on the beaches of Pehuen Co was originated due to an extensive frontal storm. The winds associated with the front prevailed from the south with a maximum intensity of 63.7 km h-1. The total length of the event was approximately 33 h. The waves on the beach, favored by the strong wind, reached 5 m in height (based on SMN map data). Beach profiles were made before and after the event to estimate volumetric differences. The effects on the beach and buildings were analyzed by field recognition after the event. Based on the profile data, we observed an erosive behavior with the profile becoming concave. ZC1 had a total volume loss of 3.17 m³, specifically on the backshore. The rest of the beach remained basically constant. The erosion caused damage to the infrastructures over the dune. In September (2009) the profile had recovered 2.38 m³ with respect to the pre-storm profile. The ZC2 had a behavior similar to ZC1 in terms of sediment loss and gain. A volume of -9.16 m³ was lost. In September, a sediment recovery from the pre-storm profile of 9.04 m³ was observed (Fig. 8). ZC3 had significant erosion in the dune area, with an escarpment of 1.6 m high. In this zone of the backshore, a volume loss of 6.51 m³ was recorded between the pre- and post-storm profiles. In September, this profile did not recover as in the other two sites (ZC1 and ZC2). The escarpment began to diminish in height on December, four months after the storm occurred (Fig. 8). The ability to differentiate the behavior of the beach according to the coverage of its frontal dune is fundamental for land-use planning. Therefore, to find solutions applicable in the short and medium term is important to the natural balance, economic and social growth of these cities. It is concluded that in an erosive zone such as the central area of Pehuen Co, the frontal dune cover is decisive for coastal dynamics. The impact and recovery of the beach after storm events were better developed in places with vegetation cover over the dunes. In turn, the beach profiles in areas with perpendicular entrances to the beach had strong erosion processes and slow recovery. We recommend to modify the entrances to the beach and reduce their number as much as possible. Therefore, risk maps are needed in order to generate better planning for coastal urban development.

Los asentamientos urbanos ocasionan una degradación de las playas haciéndolas más vulnerables a los efectos de eventos naturales (olas, mareas, vientos). Por este motivo, conocer el impacto del tipo de infraestructura o vegetación en médanos frontales puede ocasionar en la playa resulta de suma utilidad para la planificación urbana. En la localidad de Pehuen Co, al sudoeste de la provincia de Buenos Aires (Argentina), se analizó la evolución de un sector específico de la playa con diferentes coberturas del médano frontal para comprender su comportamiento general (erosión y/o acreción). Para ello, se realizaron perfiles de playa mensuales y luego de tormentas fuertes, desde julio de 2007 a junio de 2010. Se eligieron tres sectores diferentes, separados 50 m entre sí, para realizar los perfiles: 1) al lado de una edificación construida sobre el médano frontal, 2) sobre el pie del médano vegetado, y 3) sobre una bajada peatonal hacia la playa. Sobre los resultados se aplicó un Análisis de Componentes Principales (ACP) y se calcularon los volúmenes sedimentarios. Con el fin de completar el análisis se creó una matriz de doble entrada que permitió observar los desplazamientos y comportamientos de las geoformas en cada perfil. Finalmente, para evaluar los daños y respuesta en los perfiles de playa ante eventos erosivos se evaluó el impacto de uno de los temporales de viento más fuertes del período. Se concluyó que la cobertura del médano frontal es decisiva para la dinámica litoral. El impacto y la recuperación de la playa luego de eventos de tormenta fueron mejores donde había coberturas con vegetación. A su vez, los perfiles de playa en zonas con bajadas a la playa perpendiculares a la misma tuvieron fuertes procesos erosivos y lenta recuperación de sedimentos. Las diferentes respuestas de la playa según las condiciones que posee el médano frontal serán de ayuda a quienes deben tomar decisiones al momento de planificar la urbanización y emprendimientos a corto, medio y largo plazo sobre la franja costera.

The aim of this study was to analyze the influence of vegetation on the spatial distribution of winter air temperature in order to determine the appropriate percentage of vegetation necessary to create a more comfortable environment during the coldest months in Pehuén Co (Argentina). The town was sub-divided into three regions according to the amount of vegetation: greater than 80%, between 40 and 80% and less than 40%. The Normalized Difference Vegetation Index (NDVI) and the Land Surface Temperature (LST) were applied. Air temperature data were analyzed using Kruskal-Wallis test in order to determine the relationship between air temperature and the vegetation coverage. The heavily vegetated region (>80%) presented an air temperature increase during the morning. The LST presented lower values in regions with more vegetation. It was concluded that the appropriate percentage of vegetation necessary to generate touristic activities in the winter months and/or prevent possible uncomfortably cold situations for people outdoors must be greater than 40%. These results provide a guide to urban planning in sustainable coastal towns.

El objetivo de este trabajo fue determinar el porcentaje ideal de cobertura vegetal para generar temperatura del aire más confortable durante los meses más fríos en la localidad costera de Pehuen Co (Argentina). Se subdividió su plano según la cantidad de vegetación: > al 80 %, entre 80 y 40 % y < al 40 %. Se analizó la variación del Índice Normalizado de Vegetación y la Temperatura de Superficie Terrestre (TST) en la villa. Se midió la temperatura del aire (Ta) en recorridos por la localidad y se aplicó el test Kruskal-Wallis para determinar las diferencias en la temperatura de las diferentes áreas. En la cobertura vegetal densa (> 80 %) se registró una mayor Ta en las horas de la mañana respecto de las otras dos clases. Se observó que donde las áreas arboladas fueron > 80 % la TST fue menor y viceversa. Se concluyó que para generar los mayores beneficios en la implementación de actividades turísticas en los meses de invierno y/o prevenir posibles situaciones desconfortables por frío la cobertura vegetal necesaria debe ser superior al 40 %. Estos resultados proporcionan una guía para la planificación urbana de localidades costeras turísticamente más sustentables.

The seasonal morphodynamic classification of Necochea and Quequén beaches (Buenos Aires Province, Argentina) was determined. Based on 102 seasonal beach profiles and sediment sampling between February 2006 and December 2009, variations in morphology and sediment budgets of five beaches were studied. According to the dimensionless fall parameter and the relative tide range, the beaches were classified depending on their modal morphodynamic state. In Quequén, beaches presented intermediate and reflective states, whereas in Necochea they presented dissipative states. The Iribarren number showed that plunging and spilling breakers predominated in Quequén and Necochea, respectively. In winter, the beaches became more dissipative, while in summer-autumn they were more reflective. This general behavior agrees with the erosion/accretion cycles. Beach profile variability was higher in Quequén. These results have been used to elaborate the coastal management program of the area.

Se realizó la clasificación morfodinámica estacional de playas de Necochea y Quequén (provincia de Buenos Aires, Argentina). Se analizaron la morfología y las variaciones sedimentarias de cinco playas a partir de 102 perfiles topográficos estacionales y muestreos de sedimentos realizados entre febrero de 2006 y diciembre de 2009. Mediante el parámetro adimensional de asentamiento y la amplitud relativa de mareas, las playas fueron clasificadas de acuerdo con su estado morfodinámico predominante. En las playas de Quequén prevalecieron los estados morfodinámicos intermedios y reflectivos, mientras que en las de Necochea prevaleció el estado disipativo. De acuerdo con el número de Iribarren, el tipo de rompiente predominante fue en voluta en Quequén y en derrame en Necochea. Durante el invierno, todas las playas presentaron un estado más disipativo, mientras que en verano y otoño un estado más reflectivo, en concordancia con los ciclos de erosión/acreción. Las playas con mayor variabilidad morfodinámica fueron las de Quequén. Estos resultados han sido empleados en la elaboración del plan de manejo costero del área estudiada.

Urbanization is a territorial and socioeconomic process that induces a radical transformation of land/use cover. It produces great changes in the environment and therefore, is the principal cause of environmental problems and risks. Based on aerial photographs and satellital images, urban growth dynamics and land/use cover change were evaluated at the coastal urban area of Necochea municipality (Argentina). Between 1967 and 2004, urban land/cover use increased from 21,95 to 28,44 % while non urban land/cover use descended. Population growth exce-deed urban expansion rate, estimating that the densification of urban occupation is notably higher than the urban sprawl growth.

La urbanización es un proceso territorial y socioeconómico que induce una transformación radical del uso/cobertura del suelo y constituye el proceso que mayores cambios produce en el medio ambiente y, por lo tanto, está íntimamente ligado al incremento de los problemas y riesgos ambientales. Mediante fotografías aéreas e imágenes satelitales se evaluó la dinámica del crecimiento urbano y los cambios del uso/cobertura del suelo del área urbana costera del Partido de Necochea (Argentina). Desde el año 1967 al 2004, el espacio ocupado por el uso del suelo urbano se incrementó de 21,95 a 28,44% del área total estudiada, en detrimento del uso no urbano. El crecimiento de la población acompañó y superó significativamente el ritmo de expansión urbana, evidenciando que el proceso de densificación de la ocupación es notablemente superior al del crecimiento de la mancha urbana.