Comportamiento térmico en ríos mediterráneos andinos de la zona centro-sur de Chile

Despite of the importance of temperature in the fluvial ecosystems, the knowledge of its spatial and temporal variability in Andean rivers is limited, thus it is necessary to clarify the relative importance of site-specific factors in controlling the temperature of rivers. The aim of this research was to characterize the thermal regime of five Andean streams through an altitudinal gradient. The results show that there is a spatial and temporal variability in water temperature with a relatively rapid rise in temperature in mid-December, being stable in January and February, and a rapid decrease at the beginning of March and April. The thermal heterogeneity recorded in the high Andean zone of the Biobio River Basin makes it clear that geomorphology characteristics of each site are important in regulating water temperature, associated mainly with the altitude and shade; this latter mainly generated by high mountains and in some cases by the timberline. It is known that thermal variability, mainly the maximum and minimum mean temperatures; causing severe stress on stenotherm organisms. Therefore, a deeper knowledge of the river temperature is essential for the management and future protection of the Andean freshwater ecosystems to mitigate the impacts associated to the global warming.A pesar de la importancia que tiene la temperatura en los sistemas fluviales, el conocimiento de su variabilidad espacio-temporal en ríos de Chile es limitado. Tales estudios son necesarios para aclarar la importancia relativa de los factores locales a la hora de controlar la temperatura de los ríos. La presente investigación tuvo por objetivo caracterizar el régimen térmico de cinco ríos andinos de la región del Biobío a través de un gradiente altitudinal. Los resultados muestran que existe una variabilidad espacio-temporal en la temperatura del agua con un incremento relativamente rápido de la temperatura a mediados de diciembre, manteniéndose en enero y febrero, para disminuir rápidamente a principio de marzo y abril. La heterogeneidad térmica encontrada en la zona andina de la cuenca del río Biobío deja de manifiesto que las características geomorfológicas de cada sitio son relevantes en la regulación de la temperatura del agua, asociada principalmente a la altitud y sombra, esta última generada principalmente por las altas montañas y en algunos casos por la vegetación arbórea. Se prevé que cambios principalmente en las temperaturas medias máximas y mínimas podrían ocasionar un severo estrés en organismos estenotermos. Por lo tanto, un conocimiento detallado de la temperatura en ríos andinos podría proveer de información necesaria para direccionar la mitigación de los impactos asociados al calentamiento global

Importancia de la vegetación ribereña de Nothofagus dombeyi (Mirb.) Oerst. en el régimen térmico de sistemas fluviales andinos del sur de Chile

Globally, the river temperatures is a research subject, but the spatio-temporal va riability of various river systems is still limited and unknown in some cases. This study aimed to compare the natural thermal regime of Andean river ecosystems with different riparian vegetation (steppe and Nothofagus dombeyi forest). The temperature of the sites was registered with a 15 min time resolution from January to July 2011. The average, maximum and daily temperature range of water showed significant differences, with lower values in the presence of N. dombeyi. Regarding the daily cycle, a slight delay was observed in the minimum temperature and an advance in the maximum temperature for the native forest site. Therefore, performing continuous monitoring using temperature sensors made it possible to determine contrasts in the thermal regime suggesting that the shade generated by the canopy reduces the solar radiation and the maximum temperature (± 4 °C) in Andean rivers. Furthermore, the conservation of forest cover of N. dombeyi in the Andean region might be important to moderate and mitigate the occurrence of higher temperatures due to global warming scenarios projected for the area.A nivel global la temperatura de los ríos sigue siendo tema de investigación en ecología fluvial, pero el conocimiento de su variabilidad espacio-temporal en diversos sistemas fluviales aún es limitada y en algunos casos desconocida. Este estudio tuvo por objetivo comparar el régimen térmico natural de dos ecosistemas fluviales andinos con diferente vegetación ribereña (estepa y bosque de Nothofagus dombeyi). La temperatura en ambos sitios fue registrada con una resolución de 15 min desde enero a julio de 2011. La temperatura media, máxima y rango diario del agua mostraron diferencias significativas, con valores más bajos en el río con presencia de N. dombeyi. En relación al ciclo diario, se observó un leve retraso en la temperatura mínima y adelanto en la máxima para el río con bosque nativo. La realización de monitoreos continuos mediante sensores de temperatura permitió determinar contrastes en el régimen térmico y sugiere que la sombra generada por el dosel reduce la radiación solar que recibe el río y la temperatura máxima (± 4 °C) en ríos andinos. Asimismo, la conservación de la cobertura boscosa de N. dombeyi en la zona andina podría ser importante para moderar y mitigar la ocurrencia de temperaturas más altas a consecuencia de los escenarios de calentamiento global proyectados para la zona

Forest hydrology in Chile: Past, present, and future

This paper reviews the current knowledge of hydrological processes in Chilean temperate forests which extend along western South America from latitude 29° S to 56 ° S. This geographic region includes a diverse range of natural and planted forests and a broad sweep of vegetation, edaphic, topographic, geologic, and climatic settings which create a unique natural laboratory. Many local communities, endangered freshwater ecosystems, and downstream economic activities in Chile rely on water flows from forested catchments. This review aims to (i) provide a comprehensive overview of Chilean forest hydrology, to (ii) review prior research in forest hydrology in Chile, and to (iii) identify knowledge gaps and provide a vision for future research on forest hydrology in Chile. We reviewed the relation between native forests, commercial plantations, and other land uses on water yield and water quality from the plot to the catchment scale. Much of the global understanding of forests and their relationship with the water cycle is in line with the findings of the studies reviewed here. Streamflow from forested catchments increases after timber harvesting, native forests appear to use less water than plantations, and streams draining native forest yield less sediment than streams draining plantations or grassland/shrublands. We identified 20 key knowledge gaps such as forest groundwater systems, soil–plant-atmosphere interactions, native forest hydrology, and the effect of forest management and restoration on hydrology. Also, we found a paucity of research in the northern geographic areas and forest types (35-36 ° S); most forest hydrology studies in Chile (56 %) have been conducted in the southern area (Los Rios Region around 39-40 ° S). There is limited knowledge of the geology and soils in many forested areas and how surface and groundwater are affected by changes in land cover. There is an opportunity to advance our understanding using process-based investigations linking field studies and modeling. Through the establishment of a forest hydrology science “society” to coordinate efforts, regional and national-scale land use planning might be supported. Our review ends with a vision to advance a cross-scale collaborative effort to use new nation-wide catchment-scale networks Long-term Ecosystem Research (LTER) sites, to promote common and complementary techniques in these studies, and to conduct transdisciplinary research to advance sound and integrated planning of forest lands in Chile

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Régimen térmico de ríos: desarrollo, verificación y aplicación de un modelo numérico

Se aplica el método de los volúmenes finitos y se generaliza la estrategia ultimate para la solución de la ecuación advección-difusión-reacción con parámetros variables, a fin de obtener resultados con difusión numérica despreciable. El modelo se verifica mediante el cálculo de problemas con solución analítica conocida, mostrando su aptitud para simular el transporte difusivo y advectivo de propiedades escalares en el agua. Se aplica para calcular la temperatura en un tramo de 32 km del río Itata bajo, ubicado en Chile Central, donde se midió la temperatura del río y las variables que controlan el régimen térmico en varios puntos. Se presentan resultados para cuatro períodos de doce días de duración, correspondientes a escenarios de invierno, primavera, verano y otoño. La temperatura media medida en los escenarios de invierno y verano es constante, igual a 9.6 y 24.0°C, respectivamente, y no cambia a lo largo del tramo. En los escenarios medidos de otoño y primavera se observa un leve aumento a lo largo del tramo igual a 0.45 y 0.74°C, respectivamente. La amplitud de la oscilación térmica diaria medida en el escenario de invierno es despreciable, igual a 0.7°C y muy significativa en el de verano, igual a 8.4°C. Se observa que sólo en el escenario medido de verano dicha amplitud aumenta a lo largo del tramo de estudio, a razón de 0.175°C/km. El modelo desarrollado predice de manera adecuada el complejo comportamiento que exhibe la temperatura medida durante los cuatro escenarios analizados, constituyendo una herramienta de simulación con capacidad predictiva

Respuesta hidrológica de una cuenca de meso escala frente a futuros escenarios de expansión forestal

A global level more than half of the water generated through the process of runoff is used by man. In south-central Chile the watersheds have been subjected to intensive processes of land use changes, including expansion of forest plantations with exotic species. This study evaluates the hydrological effects of future scenarios for forest expansion in a basin of mesoscale (4.340 km2) using the SWAT model. The scenarios were constructed through logistic regression model forest development planning to the years 2018, 2028 and 2038. The results of the validation process show that the model has good capacity to represent the hydrology of the watershed under analysis. Simulations indicate a decreasing trend in flows especially in the dry season. For some scenarios, decreasing summer flows exceed 50% respect to the base period. This decreasing trend is consistent with those reported by other authors in basins of small and meso-scale.A nivel global más de la mitad del agua generada a través del proceso de escorrentía es usada por el hombre. En el centro-sur de Chile las cuencas hidrográficas han sido sometidas a intensas transformaciones territoriales, incluyendo la forestación masiva con especies exóticas. Este estudio evalúa el efecto hidrológico de futuros escenarios de expansión forestal en una cuenca de meso escala (4.340 km²) utilizando el modelo SWAT. Los escenarios fueron construidos a través del modelo de regresión logística proyectando el desarrollo forestal hacia los años 2018, 2028 y 2038. Los resultados muestran una tendencia a la disminución de los caudales, especialmente en la época de estiaje. Para algunos escenarios la disminución de los caudales de verano supera el 50% respecto al periodo base. Esta tendencia decreciente de los caudales, producto del aumento de la cobertura forestal, es consistente con la reportada por otros autores en cuencas de pequeña y meso-escala

Climate Change, Water Scarcity in Agriculture and the Economy-Wide Impacts in a CGE Framework

This paper analyzes the economic impacts of changes in water availability due to climate change. We develop a new modeling approach as an alternative to include water as a production factor within a global CGE model. We tailor the structure of the ICES model to characterize the key features of the world economy with a detailed representation of the agricultural sector. In order to reach this objective, a new database has been built to explicitly consider water endowments, precipitation changes, and unitary irrigation costs. Results suggest different economic consequences of climate change depending on the specific region. Impacts are related to change in crop production, endowment demands, and international trade

Modeling Biological Oxygen Demand Load Capacity in a Data-Scarce Basin with Important Anthropogenic Interventions

Most water bodies are currently used as receptors for pollutants coming mainly from the industrial and domestic sectors. The Biobio river is subjected to multiple anthropogenic pressures such as industrial water supply, drinking water, hydroelectric power generation, agriculture, and the final receptor body of a large amount of industrial and urban waste, pressures that will intensify due to the decrease in water flow as a result of climate change. In this context, organic contamination has been found mainly from sewage discharges and oxidizable waste discharges generated by industrial processes. In this sense, the objective of this research is to determine the Biological Oxygen Demand Loading Capacity (LC) in a basin with a low density of water quality data subjected to strong anthropogenic pressures. To estimate the carrying capacity in a section of the Biobio River, the water quality model River and Stream Water Quality Model- Qual2K version 2.11b8, developed by Chapra, was used. This model solves the Streeter-Phelps equation, proposing an analytical expression to relate the dissolved oxygen (DO) and biochemical oxygen demand (BOD5) variables. These variables were modeled for different critical scenarios of minimum flows in return periods of 5, 50, and 100 years, determining that the studied section of the Biobio river would have a high carrying capacity to not be affected by its organic matter pollution