Browsing by Author "Ortiz, Cristian"

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    Evaporation from shallow groundwater in closed basins in the Chilean Altiplano
    (TAYLOR & FRANCIS LTD, 2010) Johnson, Eduardo; Yanez, Jose; Ortiz, Cristian; Munoz, Jose
    The hydrological cycle in arid and semi-arid climates is highly controlled by evaporation. The correct quantification of this process is essential for improving the accuracy of water balance estimates, especially in closed basins. The objective of this paper is to characterize evaporation rates from shallow groundwater using the chamber approach in six closed basins in the Altiplano of northern Chile. Measurements were made at 49 locations with water-table depths ranging from 0.09 m to 3.3 m. Estimated daily evaporation rates appeared to be strongly related to groundwater depth and soil texture. In particular, the highest rates were recorded in areas with high groundwater tables and coarse-grained soils. Evaporation curves were derived by fitting exponential and power relationships as functions of the groundwater depths that we proposed to use in the study area. An application of these curves for the Salar de Pedernales basin produced an estimated evaporation flow of 530 L s(-1), using the average curve.
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    Modeling changes to the hydrodynamic characteristics of agglomerated copper tailings
    (ELSEVIER, 2011) Fernanda Hernandez Lopez, Maria; Ortiz, Cristian; Bonilla, Carlos A.; Gironas, Jorge; Francisco Munoz, Jose
    This paper describes the effect of acid leaching on the hydrodynamic properties of agglomerated copper tailings. Both the suction and the hydraulic conductivity curves were obtained before and after acid application in laboratory columns under unsaturated flow conditions. Using a classical approach originally developed for water and soil, we determined whether the post-acid application characteristic curves could be obtained from the pre-acid application ones. Results showed that acid modified the hydrodynamic properties of agglomerated tailings. Both the macropore volume and the saturated hydraulic conductivity decreased. For the same water content, the unsaturated hydraulic conductivity decreased and the suction head increased. The pre-acid application characteristic curves can be used to estimate the corresponding post-acid application curves. (C) 2011 Elsevier B.V. All rights reserved.
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    Simazine transport in undisturbed soils from a vineyard at the Casablanca valley, Chile
    (2013) Suarez Poch, Francisco; Guzman, Edwin; Munoz, Jose E.; Bachmann, Jaime; Ortiz, Cristian; Alister, Claudio; Kogan, Marcelo
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    Transport of simazine in unsaturated sandy soil and predictions of its leaching under hypothetical field conditions
    (ELSEVIER, 2007) Suarez, Francisco; Bachmann, Jaime; Munoz, Jose F.; Ortiz, Cristian; Tyler, Scott W.; Alister, Claudio; Kogan, Marcelo
    The potential contamination of groundwater by herbicides is often controlled by processes in the vadose zone, through which herbicides travel before entering groundwater. In the vadose zone, both physical and chemical processes affect the fate and transport of herbicides, therefore it is important to represent these processes by mathematical models to predict contaminant movement. To simulate the movement of simazine, a herbicide commonly used in Chilean vineyards, batch and miscible displacement column experiments were performed on a disturbed sandy soil to quantify the primary parameters and processes of simazine transport. Chloride (Cl-) was used as a non-reactive tracer, and simazine as the reactive tracer. The Hydrus-1D model was used to estimate the parameters by inversion from the breakthrough curves of the columns and to evaluate the potential groundwater contamination in a sandy soil from the Casablanca Valley, Chile. The two-site, chemical non-equilibrium model was observed to best represent the experimental results of the miscible displacement experiments in laboratory soil columns. Predictions of transport under hypothetical field conditions using the same soil from the column experiments were made for 40 years by applying herbicide during the first 20 years, and then halting the application and considering different rates of groundwater recharge. For recharge rates smaller than 84 mm year(-1), the predicted concentration of simazine at a depth of I m is below the U.S. EPA's maximum contaminant levels (4 mu g L-1). After eight years of application at a groundwater recharge rate of 180 mm year I (approximately 50% of the annual rainfall), simazine was found to reach the groundwater (located at 1 m depth) at a higher concentration (more than 40 mu g L-1) than the existing guidelines in the USA and Europe. (c) 2007 Elsevier B.V.. All rights reserved.