This paper describes the design, calibration and testing processes of a new device named Automated Laboratory Infiltrometer (ALI). It allows to determinate in laboratory, under controlled conditions the saturated hydraulic conductivity (Ks) of altered or unaltered soil samples which is a key parameter to understand the movement of water through a porous medium. The ALI combines the advantages of three different approaches: measures vertical infiltration rates in a soil column, measures the actual volumes of vertically drained water through the soil column, and finally, uses heat as a natural tracer to determinate water flux rates through the porous medium; all those parameters are used to determinate Ks. The ALI was developed using the popular Arduino microcontroller board and commercially available sensors that give the whole system a low cost. Data from the ALI are recorded in a microSD memory so they can be easily read from any spreadsheet software helping to reduce time consuming and avoiding reading errors. The performance of this device was evaluated by comparing the water flow rates determined by the three approaches for which is designed; an excellent correlation among them was observed (worst correlation: R2 = 0.9826 and r-RSME = 0.94%).
This work studies the statistical characteristics of potential evapotranspiration calculations and their relevance within the water balance used to determine water availability in hydrological basins. The purpose of this study was as follows: first, to apply a missing data reconstruction scheme in weather stations of the Rio Queretaro basin; second, to reduce the generated uncertainty of temperature data: mean, minimum, and maximum values in the evapotranspiration calculation which has a paramount importance in the manner of obtaining the water balance at any hydrological basin. The reconstruction of missing data was carried out in three steps: (1) application of a 4-parameter sinusoidal type regression to temperature data, (2) linear regression to residuals to obtain a regional behavior, and (3) estimation of missing temperature values for a certain year and during a certain season within the basin under study; estimated and observed temperature values were compared. Finally, using the obtained temperature values, the methods of Hamon, Papadakis, Blaney and Criddle, Thornthwaite, and Hargreaves were employed to calculate potential evapotranspiration that was compared to the real observed values in weather stations. With the results obtained from the application of this procedure, the surface water balance was corrected for the case study.
<p>The hydraulic head is an important variable to determine the functioning of water in the subsoil; however, its spatial characterization is complicated due to the variability it presents in an aquifer. Measuring hydraulic head in piezometers or observation wells involves costs, so in some cases there is little data available. To obtain reliable configurations of the hydraulic head spatial distribution in an aquifer, interpolation methods that require few measurements have been used. Ordinary kriging is one of the most widely used spatial interpolation algorithms in geostatistics, which employs a theoretical variogram (circular, exponential, Gaussian, etc.). The variogram is a function whose parameters (nugget, sill and range) must be optimized because the accuracy of the estimation depends on them. As far as it has been reviewed in the literature, the adjustment of theoretical variograms has been carried out by means of genetic algorithms considering bi-objective functions where only the error in the adjustment of the variogram and the difference between the measured values and the estimated values by means of ordinary kriging are taken into account. In this paper we propose the adjustment using a new multiobjective function, where simultaneously the variogram adjustment, the accuracy of the interpolation result and the estimation error variances are considered. This nonlinear optimization problem contains three secondary objectives. The first is to obtain the best fit between the experimental variogram and the theoretical variogram function. Secondly, the aim is to minimize the difference between the measured values and the ordinary kriging estimates (measured with the mean square error) and thirdly that the error variances in the estimation are well represented by the selected model (using the standard mean square error). The tests of the proposed procedure were carried out with data measured in El Palmar aquifer located in the northern part of the state of Zacatecas, Mexico. The performance of this procedure was evaluated for different weights assigned to each of the secondary objectives. In the models where only the variogram adjustment is considered, the mean squared error and the standardized mean squared error turned out to be very large, it was also observed that when the estimation error variance is not taken into account in the objective function, the standardized mean squared error ranges from 20.94 to 56.41. It was observed that when the estimation error variance is incorporated in the objective function (even when its weight is small) the estimation errors are very close to the minimum obtained and that the variances are very reliable (with the standardized mean square error between 0.65 and 1.35).</p>
Resumen: Los prototipos de lisímetros de pesada (LP1, LP2, LP3 y LP4) permiten determinar la evapotranspiración de los cultivos a partir del balance hídrico obtenido de la variación del peso del recipiente de cultivo y del peso del depósito de drenaje. En el modelo LP1 la solución elegida para el depósito consistió en medir el peso del agua percolada procedente del recipiente de cultivo mediante un depósito cilíndrico de 5,36 litros de capacidad (diámetro 210 mm x 155 mm de altura) con una célula de carga de 10 kg. En los modelos LP2 y LP3, se aumentó la capacidad del depósito de drenaje a 7,77 litros (diámetro 300 mm x 110 mm de altura), con una célula de carga de 10 kg. La altura total de los modelos LP1, LP2 y LP3 se fue reduciendo de 155 mm a 110 mm. En el modelo LP4, el diseño del depósito de drenaje varió sustancialmente, optándose por un diseño rectangular que, con una capacidad de 7,2 litros (360 x 160 x 125 mm), permitió mejorar la compacidad del conjunto manteniendo la resolución deseada para una célula de carga de 10 kg. La evolución del diseño del depósito de drenaje en los diversos modelos permitió ir reduciendo la altura total de los prototipos de lisímetros de pesada facilitando su instalación y montaje. Por tanto, se puede destacar la importancia que tiene el diseño del depósito de drenaje en la precisión del lisímetro de pesada, en las que el volumen de agua de cada depósito y las células de carga condicionan la resolución obtenida.Palabras clave: volumen infiltrado, evolución de diseño. percolación IntroducciónLa estimación del consumo de agua de un cultivo es importante para determinar la cantidad de agua que se requiere para obtener la mayor productividad, existen algunas metodologías para monitorear esta, los lisímetros de pesada son modelos precisos y fiables para determinarla [1]. Estos dispositivos contienen un volumen de suelo aislado hidrológicamente circundante, por lo cual es posible controlar y medir los diferentes términos que intervienen en el balance hídrico [2].Estos dispositivos permiten entender el ciclo del movimiento del agua en el suelo, desde el punto de vista continuo, repetitivo y secuencial. Una vez que entra el agua al suelo, en forma de
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