Water table behavior and classification of phreatic risk : Lavalle, Mendoza, Argentina

A partir de la información obtenida de la red georreferenciada de freatímetros se determinó el comportamiento de la profundidad freática en el Departamento Lavalle y en particular en el Distrito Costa de Araujo. Se agruparon las profundidades freáticas en intervalos 0,5 m desde la superficie hasta los 2,5 m. Se calcularon y analizaron las profundidades medias y mínimas de cada freatímetro para la serie 1983-2002 (19 años) y las medias correspondientes a marzo, junio, septiembre y diciembre. Utilizando el software Arc View se representaron gráfica y numéricamente las superficies de terreno para los diferentes intervalos. Con esta información se confeccionaron tablas de intervalos de profundidad freática y en base a ello se calificó el Riesgo Freático en Bajo, Medio y Alto, asumiendo un valor de profundidad mínima admisible de 1,5 m para prácticas de cultivos perennes. Se presenta la discusión referente a la salinidad de las aguas freáticas y su vinculación con la clorosis en vid. Resultados: el 32 y 41% de las superficies del Distrito Costa y Dpto. Lavalle, respectivamente, tienen el nivel freático medio entre 1,5 y 2,0 m de profundidad, resultando el Riesgo Freático Bajo para el Distrito Costa y Medio para el Dpto. Lavalle; septiembre es el mes más crítico con el 43 y 40% de las superficies del Distrito Costa y Dpto. Lavalle, respectivamente, con niveles freáticos medios entre 1,0 y 1,5 m de profundidad, resultando el Riesgo Freático para dicho mes Bajo para el Distrito Costa y Alto para el Dpto. Lavalle; la Subárea Costa posee las mejores condiciones de profundidad freática y edáfica para la agricultura del Departamento Lavalle; la red principal de colectores es insuficiente para producir el abatimiento general de los niveles freáticos del Departamento Lavalle.According to the information obtained from a georeferenced network of piezometers, it was determined the water table depth behavior in the Department of Lavalle and specially in the District of Costa de Araujo. The water table depths were grouped at intervals of 0.5 m, from surface to 2.5 m deep. The minimum and medium depths of each piezometer were calculated from 1983 to 2002 and also the medium depths corresponding to the months of March, June, September and December. The surface for different intervals were represented graphic and numerically by the use of Arc View software. With this information there were made tables of water table depths intervals and based on them, the phreatic risk was classified into low, medium and high assuming 1.5 m as the minimum admissible depth value for perennial crops practices. A discussion on water table salinity and its connection with vine chlorosis is presented. Results: 32 and 41% of the areas of the District Coast and Dpto. Lavalle, respectively, have the water table between 1.5 and 2.0 m deep, resulting Phreatic Low Risk for the District Coast and for the Middle Dpto. Lavalle; September is more critical with 43 and 40% of the areas of the District Coast and Dpto. Lavalle, respectively, with average groundwater levels between 1.0 and 1.5 m deep, resulting Risk Low water table for that month for the Dstrict Coast and High for the Dpto. Lavalle; the subarea Costa possesses the better conditions of phreatic and edaphic depth for the agriculture of the Department Lavalle; the main network of collectors is insufficient to produce the general depression of the phreatic levels of the Department of Lavalle.Fil: Ortíz Maldonado, Gonzalo. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ingeniería AgrícolaFil: Carmona, Víctor

Phreatic water salinity in the Mendoza river command area

La provincia de Mendoza tiene la mayor superficie regada de Argentina y cuenta con una vasta infraestructura de riego y drenaje en los cinco ríos aprovechados. Los suelos son de origen aluvial, con perfiles que alternan capas de distintas texturas, observándose la presencia de estratos muy finos -casi impermeables- que impiden el libre drenaje del agua de riego. Esta situación dinámica es más evidente a medida que el río disminuye su pendiente coincidiendo con los sectores bajos de la cuenca. La acumulación de agua produce el ascenso de los niveles freáticos hasta aproximarse a la superficie del suelo, incrementando la salinización del mismo. El área de riego del río Mendoza, con valores de salinidad media del agua en su derivación hacia la red de riego menor de 1 dS.m-1, es una de las más intensamente explotadas del país y presenta dos sectores con problemas de freática cercana a superficie. Los mismos corresponden a una zona central llamada Área de Surgencia AS y a otra llamada Área Lavalle AL. En AS hay una red de 98 pozos de observación (freatímetros) para conocer las profundidades, direcciones de flujos y calidad del agua freática. El AL tiene una red de 100 freatímetros distribuidos en tres subáreas correspondientes a tres colectores de drenajes: Tres de Mayo-Jocolí TMJ, Villa Lavalle VL y Costa de Araujo-Gustavo André CG. El presente trabajo muestra los resultados de la evaluación de la salinidad del agua freática expresada como salinidad total a 25 °C (CE) para las dos áreas de estudio. Las muestras han sido extraídas en 2002 y 2004. Los resultados indican que en los dos momentos de muestreo la mediana es menor que la media correspondiente, lo que evidencia asimetría positiva en las distribuciones. Las medianas obtenidas fueron: 6180 μS cm-1 (2002) y 6195 μS cm-1 (2004). Además se observan cambios en las distribuciones entre los momentos de muestreo y entre las áreas: en 2004 aparecen valores extremos superiores mucho mayores que en 2002, y el área VL acusa frecuencias relativas más uniformes y los mayores incrementos de CE. Se distingue también que en los dos momentos de muestreo el área AS posee los valores de posición de CE más bajos, aunque también es la zona con mayor cantidad de outliers; las áreas TMJ, CG y AS no han sufrido cambios importantes en los valores de CE en dos años, pero sí se advierte un sensible aumento de la CE en VL. Con la base de datos depurados se realizaron isolíneas para diferentes intervalos de la variable analizada (CE) que muestran espacialmente los sectores afectados con los distintos intervalos de salinidad freática.The Province of Mendoza has the largest irrigated area in Argentina with a vast irrigation and drainage infrastructure in the oases of its main five rivers. Soils are alluvial and their profiles reveal alternate layers of different textures, and very thin -almost impervious- strata prevent free drainage of irrigation water. This dynamic situation is more evident as the river slope diminishes in the lower sectors of the basin. Water accumulation raises water table level practically up to soil surface, which increases soil salinization. The command area of the Mendoza River, with mean water salinity values of less than 1 dS.m-1 at its point of diversion to the irrigation system, is one of the most intensely exploited areas in the country and has two sectors with very high water tables (our study areas): a central area known as spring water area AS, and another area identified as the Lavalle Area AL. At AS there are 98 observation wells to determine depths, flow direction, and phreatic water quality. The AL has 100 observation wells distributed in three subareas corresponding to three drainage collectors: Tres de Mayo-Jocolí TMJ, Villa Lavalle VL, and Costa de Araujo-Gustavo André CG. This paper presents the results of a phreatic water salinity assessment, which are expressed as total salinity at 25 °C (EC) for both study areas. Samples were drawn in 2002 and 2004. Results obtained show that, at the two sampling moments, the median is smaller than the corresponding mean, which is indicative of positive asymmetry in the distributions; median values were 6180 µS cm-1 (2002) and 6195 µS cm-1 (2004). There were also changes in distribution between the sampling moments and between the areas. In 2004 extreme upper values were much higher than in 2002; and in the VL area relative frequencies were more uniform while EC increments were greater. It was also observed that the AS area had the lowest EC values at both sampling moments, although it was also the area with more outliers; that there have been no significant (α = 0.05) changes in EC in the TMJ, CG and AS areas in two years but that there has been a substantial rise in EC in VL. Refined data were used to draw isolines for various intervals of the variable under analysis (EC), and they show the sectors affected by different phreatic salinity intervals.Fil: Ortíz Maldonado, Gonzalo. Universidad Nacional de Cuyo. Facultad de Ciencias AgrariasFil: Morábito, José. Universidad Nacional de Cuyo. Facultad de Ciencias AgrariasFil: Rearte, Emilio. Universidad Nacional de Cuyo. Facultad de Ciencias AgrariasFil: Mastrantonio, Leandro. Universidad Nacional de Cuyo. Facultad de Ciencias Agraria

Evaluation of a quality improvement intervention to reduce anastomotic leak following right colectomy (EAGLE): pragmatic, batched stepped-wedge, cluster-randomized trial in 64 countries

Background Anastomotic leak affects 8 per cent of patients after right colectomy with a 10-fold increased risk of postoperative death. The EAGLE study aimed to develop and test whether an international, standardized quality improvement intervention could reduce anastomotic leaks. Methods The internationally intended protocol, iteratively co-developed by a multistage Delphi process, comprised an online educational module introducing risk stratification, an intraoperative checklist, and harmonized surgical techniques. Clusters (hospital teams) were randomized to one of three arms with varied sequences of intervention/data collection by a derived stepped-wedge batch design (at least 18 hospital teams per batch). Patients were blinded to the study allocation. Low- and middle-income country enrolment was encouraged. The primary outcome (assessed by intention to treat) was anastomotic leak rate, and subgroup analyses by module completion (at least 80 per cent of surgeons, high engagement; less than 50 per cent, low engagement) were preplanned. Results A total 355 hospital teams registered, with 332 from 64 countries (39.2 per cent low and middle income) included in the final analysis. The online modules were completed by half of the surgeons (2143 of 4411). The primary analysis included 3039 of the 3268 patients recruited (206 patients had no anastomosis and 23 were lost to follow-up), with anastomotic leaks arising before and after the intervention in 10.1 and 9.6 per cent respectively (adjusted OR 0.87, 95 per cent c.i. 0.59 to 1.30; P = 0.498). The proportion of surgeons completing the educational modules was an influence: the leak rate decreased from 12.2 per cent (61 of 500) before intervention to 5.1 per cent (24 of 473) after intervention in high-engagement centres (adjusted OR 0.36, 0.20 to 0.64; P < 0.001), but this was not observed in low-engagement hospitals (8.3 per cent (59 of 714) and 13.8 per cent (61 of 443) respectively; adjusted OR 2.09, 1.31 to 3.31). Conclusion Completion of globally available digital training by engaged teams can alter anastomotic leak rates. Registration number: NCT04270721 (http://www.clinicaltrials.gov)