828 research outputs found

    Simulating the long term impact of nitrate mitigation scenarios in apilot study basin

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    The agro-hydrological model TNT2 was used to explore for a period of 14 years (1987–2001) the likelyconsequences of mitigation scenarios on nitrate contamination of the stream water in a small agriculturalcatchment. The Best Management Practices (BMPs) historically designed and implemented in 1992 andtwo devised agricultural scenarios (catch crop (CC) implementation and a global reduction of N fertilizer)are evaluated in term of nitrate contamination in the environment. Two of the BMPs consist in imple-menting natural strips of Poplar and rye-grass strips (5 meters large) along stream and ditches and thethird is a delay in the burial of wheat straws (from August to October). Simulations indicated that naturalstrips implementation would lead to a slight decrease of Nitrate Fluxes (NF) in river by respectively 3.3%and 6.6% for rye-grass and poplar strips: a benefit associated to the non fertilization of strips area. Denitri-fication has not been particularly disrupted in such areas. The delay in the burial of wheat straw in autumndecreases annual mineralization rate and annual plant uptake (by respectively 9 and 13 kg N ha−1y−1)but increases denitrification fluxes by 6 kg N ha−1y−1. This would lead to a slight decrease by 6% of NFin stream (equivalent to 3.3 mg NO3−l−1) and an average decrease of the following sunflower yield by27%. The global reduction of fertilization by 10% would decreased NF in stream by 13.8% (equivalent to8 mg NO3−l−1), with a global decrease by 8 kg N ha−1y−1of plant uptake. The cumulative effect of BMPsand CC would have together lead to a decrease of nitrate concentration from 57.5 to 46.6 mg NO3−l−1reaching the UE environmental quality objectives (below 50 mg NO3−l−1). Spring crops yield followingCC would have been penalized and the decrease of NF is balanced by an increase of denitrification fluxesin the environment contributing to release of N2O, a greenhouse gas, into the atmosphere

    Dynamics of Nitrogen loads in surface water of an agricultural watershed by modelling approach, the Save, Southwest France.

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    Agriculture is known to have a great impact of nutrients enrichment on continental water resources. In south-West of France (Gascogne region), water resource are essentially surface water and shallow aquifer. Nitrogen dynamic in river is complex and highly variable throughout season and year, depending on hydrology, landuse, removal in stream. In this context, agricultural impacts on nitrogen concentration are a matter of concern for agricultural decision-maker. In order to introduce sustainable land use concepts in this hilly, clayey and agricultural shallow soil context, the hydrological simulation model SWAT2005 has been tested as a valuable tool to evaluate the consequences of such land use changes on water and nutrient balance components. This semi-distributed hydrological model coupled with agronomical model EPIC is able to simulate the impact of each agricultural landuse at the outlet of the Save catchment (1100 km2). Hydrological parameters model are calibrated based on 14-year historical record (1994–2008). Nitrogen losses have been measured during 2 years (2006-2008) at the outlet and are used to validate the model calibration. Agricultural data at communal scale coupled with Spot image analyses have been used to evaluate agricultural distribution and pressure in SWAT. The aim of this modelling exercise is to simulate nitrogen cycle in whole agricultural Hydrological Response Units (HRU), depending on plant growth and culture rotation, to simulate accurately nitrate load in river. The ability of SWAT to reproduce nitrogen transfert and transformation at this scale and in this agricultural context will be evaluated by a discussion of importance of each nitrogen cycle process in nitrogen losses. SWAT could be a useful tool to test agricultural scenario to improve the nitrogen management in river

    Long term nitrogen budget modelling in a small agricultural watershed: hydrological control assessment of nitrogen losses with semi-distributed (SWAT) and distributed (TNT2) models

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    Nitrogen exports in catchments are known to be greatly variable because nitrogen cycle in watershed is controlled by different factors such as landuse, farm management practices, climate, soil type and hydrological setting. Our aim is to study the relative importance of the processes controlling nitrogen losses at catchment scale in the long term using a modelling approach constrained by a long term record of observations. The study area is a catchment of 330 ha with 95 % of intensive agriculture in a hilly shallow soil context, in the south west of France. Historical field rotation and nitrogen river load data have been collected for a 20 year period. Two process-based and spatially distributed models have been chosen to simulate nitrogen transfer and transformation in the whole catchment. The first one is the fully distributed TNT2 model, developed and validated in a different context (farming systems in north-western France). The second one is the widely used, semi-distributed SWAT model, used and recognizedto be realistic in many studies on nitrogen transfer in river. This comparative modelling approach was used to evaluate the effect of different modelling approaches on the identification of controlling factors, and the ability of both models to simulate alternative scenarios. The discharge, especially during storm flow, is well simulated by the curve number approach and the semi-distributed hydrological parameter description used SWAT, while the Topmodel-derived approach used in TNT2 tends to underestimate some peak discharges. Nitrogen dynamic simulations are considered to be acceptable for both models for a long time period but the use of both models allows to exhibit their respective capacity and limits. TNT2 has higher potentiality to test the impact of complex agricultural scenarios because the description of management practices and the simulation of crops to management options is more detailed. It permits the assessment of spatial interactions and focussed spatial management, like the set up of grass or tree strips. SWAT can then be used to scale up change scenarios from TNT2 small catchment results to large catchments

    Continuous measurement of nitrate concentration in a highly event-responsive agricultural catchment in south-west of France: is the gain of information useful?

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    A nitrate sensor has been set up to measure every 10 min the nitrate signal in a stream draining a small agricultural catchment dominated by fertilized crops during a 2-year study period (2006–2008) in the south-west of France. An in situ sampling protocol using automatic sampler to monitor flood events have been used to assume a point-to-point calibration of the sensor values. The nitrate concentration exhibits nonsystematic concentration and dilution effects during flood events. We demonstrate that the calibrated nitrate sensor signal gathered from the outlet is considered to be a continuous signal using the Nyquist–Shannon sampling theorem. The objectives of this study are to quantify the errors generated by a typical infrequent sampling protocol and to design appropriate sampling strategy according to the sampling objectives. Nitrate concentration signal and flow data are numerically sampled to simulate common sampling frequencies. The total fluxes calculated from the simulated samples are compared with the reference value computed on the continuous signal. Uncertainties are increasing as sampling intervals increase; the method that is not using continuous discharge to compute nitrate fluxes bring larger uncertainty. The dispersion and bias computed for each sampling interval are used to evaluate the uncertainty during each hydrological period. High underestimation is made during flood periods when high-concentration period is overlooked. On the contrary, high sampling frequencies (from 3 h to 1 day) lead to a systematic overestimation (bias around 3%): highest concentrations are overweighted by the interpolation of the concentration in such case. The in situ sampling protocol generates less than 1% of load estimation error and sample highest concentration peaks. We consider useful such newly emerging field technologies to assess short-term variations of water quality parameters, to minimize the number of samples to be analysed and to assess the quality state of the stream at any time

    Understanding nitrogen transfer dynamics in a small agricultural catchment: Comparison of a distributed (TNT2) and a semi distributed (SWAT) modeling approaches

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    The coupling of an hydrological and a crop model is an efficient approach to study the impact of the interactions between agricultural practices and catchment physical characteristics on stream water quality. We analyzed the consequences of using different modeling approaches of the processes controlling the nitrogen (N) dynamics in a small agricultural catchment monitored for 15 years. Two agro-hydrological models were applied: the fully distributed model TNT2 and the semi-distributed SWAT model. Using the same input dataset, the calibration process aimed at reproducing the same annual water and N balance in both models, to compare the spatial and temporal variability of the main N processes. The models simulated different seasonal cycles for soil N. The main processes involved were N mineralization and denitrification. TNT2 simulated marked seasonal variations with a net increase of mineralization in autumn, after a transient immobilization phase due to the burying of the straw with low C:N ratio. SWAT predicted a steady humus mineralization with an increase when straws are buried and a decrease afterwards. Denitrification was mainly occuring in autumn in TNT2 because of the dynamics of N availability in soil and of the climatic and hydrological conditions. SWAT predicts denitrification in winter, when mineral N is available in soil layers. The spatial distribution of these two processes was different as well: less denitrification in bottom land and close to ditches in TNT2, as a result of N transfer dynamics. Both models simulate correctly global trend and inter-annual variability of N losses in small agricultural catchment when a sufficient amount data is available for calibration. However, N processes and their spatial interactions are simulated very differently, in particular soil mineralization and denitrification. The use of such tools for prediction must be considered with care, unless a proper calibration and validation of the different N processes is carried out

    Liderazgo transformacional y habilidades blandas de los docentes de un instituto superior público, Arequipa 2021

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    El objetivo de la presente investigación fue determinar la relación de liderazgo transformacional y las habilidades blandas de los docentes de un instituto superior público en Arequipa 2021. El tipo de investigación fue no experimental - transversal porque no se manipularon las variables y se aplicó la encuesta en un único periodo de tiempo y tiene un diseño correlacional que permitió identificar el grado de asociación entre variables. Para la recolección de datos se utilizó como técnica la encuesta y como instrumento el cuestionario. La población estuvo conformada por 105 docentes y la muestra fue de 84 docentes a quienes se aplicó la encuesta. Como resultado principal se acepta la hipótesis general, existe una relación moderada y significativa entre liderazgo transformacional y habilidades blandas, obteniendo un coeficiente de Spearman del 0,653 y una significancia de 0.000

    Propuesta de mejora mediante Six Sigma y la productividad en el área de fabricación-vacumpanes en la Empresa Agroindustrial Tuman - 2020

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    La investigación mostró el problema del aumento del tiempo en el proceso de cristalización del azúcar granulado, entonces nuestro objetivo principal fue proponer el Six Sigma e influir positivamente a la productividad de la Empresa Agroindustrial Tuman S.A.A. En el área de fabricación. La estructura de la investigación era de tipo básica, con un nivel explicativa, bajo un enfoque cuantitativo y con diseño no experimental, siendo nuestra población la producción anual de azúcar en toneladas en el área de fabricación (Vacumpanes) del año 2020 y la muestra para el análisis de la investigación se considera la producción de azúcar en toneladas de un periodo de 84 días del área de vacumpanes. En la investigación se realizó una simulación de los posibles resultados sin generar la implicancia en el Six Sigma con este ensayo resultó el incremento de la eficiencia con una diferencia a favor de 16,62% aumentando la cantidad de azúcar granulada y la mejora de la eficacia con una diferencia a favor de 17,01% para mejorar las horas en la ejecución de los procesos y otro resultado importante fue el incremento de la productividad con una diferencia mejorada de 29,24%. Finalmente se concluyó que al proponer el FMEA, Check List (lista de control) y capacitaciones detalladas en cada proceso redujo las perdidas observadas en el área de fabricación mediante la reducción de los defectos y que después de la propuesta y su aplicación nos resulte en un periodo de mediano plazo de pasar de 2.6 Seis Sigma a 4.0

    Aplicación de gestión de almacenes para mejorar la productividad en el almacén de la empresa Fersanta SAC, Chimbote 2021

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    El presente trabajo de investigación tuvo como objetivo principal determinar en qué medida la gestión de almacenes mejora la productividad en el almacén de la empresa Fersanta SAC. Para la metodología se utilizó la investigación aplicada, de enfoque cuantitativo, nivel explicativo y diseño pre experimental. La población estuvo constituida de 171 pedidos mensuales atendidos por el área de almacén; como instrumentos se utilizaron el reporte de inventario, reporte de despacho, check list y el cronómetro; como técnicas se utilizaron la observación directa y el análisis documental, para así poder analizar la eficiencia y eficacia en el proceso de los despachos realizados. Para la aplicación de mejora se utilizó algunas herramientas de la gestión de almacenes como: la clasificación ABC por rotación, codificación de ubicación, señalización de almacén, programación de limpieza e inventario, además de la señalización del picking. Finalmente se concluye que en los resultados se mejoró la productividad de 63.68% a 84.33%, la eficiencia en el tiempo de despacho de 74.19% a 87.95% y la eficacia respecto al nivel de cumplimiento de despacho de 85.83% a 95.83%

    Evaluación de la calidad de agua de mar afectado por los vertimientos domésticos en la bahía del distrito de Huacho – 2021

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    Objetivo: Evaluar la calidad de agua de mar que afecta por los vertimientos domésticos en la bahía del distrito de Huacho-2021. Metodología: el tipo de investigación es aplicada, con un nivel descriptivo, cuantitativa. La población fue toda el área de la bahía, la muestra las 7 estaciones de muestreo Resultados: Los indicadores que sobrepasan el ECA son Aceites y Grasas con un valor de 7.5 mg/L y 9.2 mg/L, Plomo con un valor de 0.0083 mg/L y 0.0086 mg/L, Coliformes Totales con un valor de 16000 NMP/100 ml; los indicadores que sobrepasan el LMP son Aceites y Grasas, DBO5, DQO, Coliformes Fecales y Coliformes Termotolerantes, quien este último indicador es el más significativo con valores críticos de 2400000 NMP/100 mL y 790000 NMP/100 mL; asimismo comparando los valores de Coliformes Termotolerantes de las estaciones de agua de mar con el D.S. 0382015/MINSA se determinó que 05 estaciones están por encima del estándar de calidad de agua, el cual no es apta para bañistas ni actividades de contacto directo. Conclusión: Se acepta nuestra hipótesis alterna donde nos indica que la calidad del agua de mar está siendo afectada de manera significativa por los vertimientos domésticos en la bahía del distrito de Huacho, siendo los parámetros microbiológicos los más críticos, no solo afectando el equilibrio del ecosistema marino, sino la integridad y salud de las personas que tienen uncontacto directo con este cuerpo receptor, sobre todo si es cerca a la descarga
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