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An experimental study based on the effects of fire on soil hydrology was developed at the Experimental Station of ‘La Concordia’ (Valencia, Spain). It is located on a calcareous hillside facing SSE and composed of nine erosion plots (4 × 20 m). In summer 2003, after eight years of soil and vegetation recovery from previous fires in 1995 (with three fire treatments: T1 high‐intensity fire, T2 moderate intensity, and T3 not burnt), experimental fires of low intensity were again conducted on the plots already burnt, to study the effects of repeated fires on the soil water infiltration, soil water content and runoff. Infiltration rates and capacities were measured by the mini‐disk infiltrometer method (MDI), assessing the effects of vegetation cover by comparing the under‐canopy microenvironment (UC) and its absence on bare soil (BS), immediately before and after the fire experiments. Soil properties like water retention capacity (SWRC) and water content (SWC) were also determined for the different fire treatments (T1, T2 and T3) and microsites (UC and BS). Hydrological parameters, such as runoff and infiltration rate, were monitored at plot scale from July 2002 to July 2004. In the post‐fire period, data displayed a 20% runoff increase and a decrease in infiltration (18%). Differences in the steady‐state infiltration rate (SSI) and infiltration capacity (IC) were tested with the MDI on the different treatments (T1, T2 and T3), and between the UC and BS microsites of each treatment. After fire, the SSI of the UC soil declined from 16 mm h−1 to 12 mm h−1 on T1, and from 24 mm h−1 to 19 mm h−1 on T2. The IC was reduced by 2/3 in the T1 UC soil, and by half on T2 UC soil. On the BS of T1 and T2, the fire effect was minimal, and higher infiltration rates and capacities were reached. Therefore, the presence/absence of vegetation when burnt influenced the post‐burnt infiltration patterns at soil microscale. On the T3, different rates and capacities were obtained depending on the microsites (UC and BS), with higher SSI (25 mm h−1) and IC (226 mm h−1) on BS than on UC (SSI of 18 mm h−1 and IC of 136 mm h−1). The SWRC and SWC were recovered from 1995 to 2003 (prior to the fires). The 2003 fire promoted high variability on the SWC at pF 0·1, 2 and 2·5, and the SWRC on burnt soils were reduced. To summarize, the IC and SSI post‐fire decreases were related to the lower infiltration rate at plot scale, the significant differences in the SWRC between burnt and control treatments, and the increase in the runoff yield (20%). According to the results, the MDI was a useful tool to characterize the soil infiltration on the vegetation patches of the Mediterranean maquia, and contrary to other studies, on the UC soil, the infiltration rate and IC, when soil was dry, were lower than that obtained on BS. Once the soil gets wet, similar values were found on both microenvironments. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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In this paper, we present a conceptual‐numerical model that can be deduced from a calibrated finite difference groundwater‐flow model, which provides a parsimonious approach to simulate and analyze hydraulic heads and surface water body–aquifer interaction for linear aquifers (linear response of head to stresses). The solution of linear groundwater‐flow problems using eigenvalue techniques can be formulated with a simple explicit state equation whose structure shows that the surface water body–aquifer interaction phenomenon can be approached as the drainage of a number of independent linear reservoirs. The hydraulic head field could be also approached by the summation of the head fields, estimated for those reservoirs, defined over the same domain set by the aquifer limits, where the hydraulic head field in each reservoir is proportional to a specific surface (an eigenfunction of an eigenproblem, or an eigenvector in discrete cases). All the parameters and initial conditions of each linear reservoir can be mathematically defined in a univocal way from the calibrated finite difference model, preserving its characteristics (geometry, boundary conditions, hydrodynamic parameters (heterogeneity), and spatial distribution of the stresses). We also demonstrated that, in practical cases, an accurate solution can be obtained with a reduced number of linear reservoirs. The reduced computational cost of these solutions can help to integrate the groundwater component within conjunctive use management models. Conceptual approximation also facilitates understanding of the physical phenomenon and analysis of the factors that influence it. A simple synthetic aquifer has been employed to show how the conceptual model can be built for different spatial discretizations, the parameters required, and their influence on the simulation of hydraulic head fields and stream–aquifer flow exchange variables. A real‐world case was also solved to test the accuracy of the proposed approaches, by comparing its solution with that obtained using finite‐difference MODFLOW code. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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Servando Chinchón-Payá Bravo I. De Blas Roldán M. J. Nueda Andreu F. Garcia 《Environmental Earth Sciences》2010,61(5):1005-1012
A model has been developed to predict the origin of uncontrolled water flows. For this purpose, we analysed a total of 52
elements using ICP techniques on 72 water samples in all: 40 of them from leaks in the drinking water supply network and the
remaining 32 from groundwater outcrops. The study focused on the cases registered within the Alicante town limits (Spain).
The use of multivariate statistical classification tools such as discriminant analysis made it possible not only to reduce
the number of analytes, but also to design a predictive model capable of assigning the group to which a new sample belongs.
The elements that comprise the model are B, Mn, Te, Ce, Re, Sr, Li and Tl. Given the concentration of each element in the
sample, the model can assign its precedence with a total success rate higher than 94%. 相似文献
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Hydrogeochemical effects of groundwater mining of the Sierra de Crevillente Aquifer (Alicante,Spain) 总被引：1，自引：0，他引：1
The groundwater mining of the Crevillente aquifer (southeastern Spain) has resulted in the progressive deterioration of water quality, with particularly significant increases in chloride, sulfate, and sodium. The possibility of a vertical hydrochemical zoning is deduced that would require examining the importance of the geometry and lithology (evaporitic materials) in the salinization process. The time of water-rock contact (residence time) and dilution by infiltration of rainwater also influences the hydrogeochemistry of the aquifer. The hydrochemical data are useful in defining the conceptual model of the aquifer, completely karstified with relative homogeneity.Project AMB92-0211 (CICYT) 相似文献
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In the Mediterranean area, forest fires have become a first-order environmental problem. Increased fire frequency progressively reduces ecosystem recovery periods. The fire season, usually followed by torrential rains in autumn, intensifies erosion processes and increases desertification risk. In this work, the effect of repeated experimental fires on soil response to water erosion is studied in the Permanent Field Station of La Concordia, Valencia, Spain. In nine 80 m2 plots (20 m long × 4 m wide), all runoff and sediment produced were measured after each rainfall event. In 1995, two fire treatments with the addition of different biomass amounts were applied. Three plots were burned with high fire intensity, three with moderate intensity, and three were unburned to be used as control. In 2003, the plots with the fire treatments were burned again with low fire intensities. During the 8-year interval between fires, plots remained undisturbed, allowing regeneration of the vegetation–soil system. Results obtained during the first 5 months after both fire experiments show the high vulnerability of the soil to erosion after a repeated fire. For the burned plots, runoff rates increased three times more than those of 1995, and soil losses increased almost twice. The highest sediment yield (514 g m− 2) was measured in 2003, in the plots of the moderate fire intensity treatment, which yielded only 231 g m− 2 of sediment during the corresponding period in 1995. Runoff yield from the control plots did not show significant temporal changes, while soil losses decreased from 5 g m− 2 in the first post-fire period to 0.7 g m− 2 in the second one. 相似文献
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Recharge to mountainous carbonated aquifers in SE Spain: Different approaches and new challenges 总被引：1，自引：0，他引：1
J.M. Andreu F.J. Alcalá Á. Vallejos A. Pulido-Bosch 《Journal of Arid Environments》2011,75(12):1262-1270
As in most semiarid regions, the main source of freshwater in SE Spain is its aquifers, and their exploitation has enabled the development of highly profitable irrigated agriculture and tourism industries. The application of sustainable water management plans requires aquifer recharge to be quantified and its spatial pattern evaluated. This paper gives a comprehensive review of various recharge studies in mountainous carbonated aquifers, the most important groundwater reservoirs in SE Spain. Quantification of potential recharge rates and their spatial variability are illustrated using satellite-based modeling and tracer techniques. Actual recharge figures from the application of a lumped model based on water table fluctuations are also presented. Potential recharge relative to actual recharge is around 1 in small aquifers and flat areas and may increase up to 1.3 in heterogeneous mountainous aquifers with deep water levels due to losses of recharge in transit in the vadose zone. The complex interaction between climate, geology, aquifer geometry, topography, soil properties and the degree of karstification prevents the systematization of any particular technique to quantify potential recharge. The use of water table fluctuation methods for actual recharge evaluation requires daily time steps to compute unnoticed small recharge events. Therefore, the monitoring of environmental variables and the use of complementary techniques for comparison are recommended. Despite their importance for the correct assessment of recharge in the region, uncertainty analyses are still scarce, and the natural variability of recharge is unknown in most cases. Effort is required to improve the spatial and temporal characterization of recharge through the integration of interdisciplinary sciences. 相似文献
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Abstract An alternative procedure for assessment of reservoir Operation Rules (ORs) under drought situations is proposed. The definition of ORs for multi-reservoir water resources systems (WRSs) is a topic that has been widely studied by means of optimization and simulation techniques. A traditional approach is to link optimization methods with simulation models. Thus the objective here is to obtain drought ORs for a real and complex WRS: the Júcar River basin in Spain, in which one of the main issues is the resource allocation among agricultural demands in periods of drought. To deal with this problem, a method based on the combined use of genetic algorithms (GA) and network flow optimization (NFO) is presented. The GA used was PIKAIA, which has previously been used in other water resources related fields. This algorithm was linked to the SIMGES simulation model, a part of the AQUATOOL decision support system (DSS). Several tests were developed for defining the parameters of the GA. The optimization of various ORs was analysed with the objective of minimizing short-term and long-term water deficits. The results show that simple ORs produce similar results to more sophisticated ones. The usefulness of this approach in the assessment of ORs for complex multi-reservoir systems is demonstrated. Citation Lerma, N., Paredes-Arquiola, J., Andreu, J., and Solera, A., 2013. Development of operating rules for a complex multi-reservoir system by coupling genetic algorithms and network optimization. Hydrological Sciences Journal, 58 (4), 797–812. 相似文献
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The Valle de Toluca aquifer, located in the Highlands of Mexico, is subject to intensive exploitation to meet the water demand in the valley, as well as for part of Mexico City. This intensive exploitation has produced a decline in groundwater level, land subsidence problems and a decrease in river and spring flows. This study is aimed at determining the extent to which the intensive groundwater abstraction is able to affect and modify the chemical characteristics of the water, using statistical techniques and historical data on the main physico-chemical parameters. Some changes in the chemical characteristics have been verified; initial water abstractions were mainly derived from a local flow zone (rainwater recharge and lateral flows from other aquifers), but currently the chemical characteristics are those of a regional flow zone, revealed by waters of sodium bicarbonate type. An increase in nitrate content has also occurred, although only occasionally is the limit for potable water (50 mg NO3- L-1) exceeded.
Resumen El acuífero del Valle de Toluca, localizado en el Altiplano Mexicano, se encuentra sometido a una intensa explotación para cubrir las necesidades de agua en el propio valle, así como parte de las de Ciudad de México. Los altos niveles de explotación han provocado el descenso del nivel piezométrico, problemas de subsidencia, disminución de caudales en ríos y desecación de manantiales. Este estudio pretender determinar en qué grado esta intensiva extracción del agua subterránea es capaz de afectar y modificar el quimismo del agua. Para ello se han empleado técnicas estadísticas y datos históricos de los principales parámetros físico-químicos. Se ha podido comprobar que existen algunos cambios en el quimismo, ya que, inicialmente, el agua extraída del acuífero estaba ligada en gran medida a un flujo local (recarga por agua de lluvia y por alimentación lateral desde otros acuíferos) mientras que ahora el quimismo es característico de un flujo regional, puesto de manifiesto por aguas de tipo bicarbonatado sódico. Adicionalmente, también se ha producido un aumento del contenido de nitratos, aunque sólo de forma ocasional se sobrepasa el límite para agua potable (50 mg NO3– L–1).
Résumé Laquifère Valle de Toluca, localisé dans les Hautes Terres du Mexique, est sujet à lexploitation intensive pour combler la demande importante en eau dans la vallée et dans une partie de Mexico. Cette exploitation intensive a causé une baisse importante des niveaux piézométriques, des problèmes daffaissement et de baisse de débits des sources et des rivières. Cette étude a pour objectif de déterminé la limite jusquà laquelle lexploitation intensive pourra affecté et modifié les caractéristiques chimiques de leau, en utilisant des techniques statistiques et des données historiques des principaux paramètres physico-chimiques. Certains changements des caractéristiques chimiques ont été vérifiés ; les premières eaux captées ont été compensées par dautres zones dalimentation (recharge par les eaux de pluie et écoulements latéraux venant dautres aquifères), mais couramment les caractéristiques chimiques sont bien ceux de la zone découlement régional, à faciès sodi bicarbonaté. Une augmentation des concentrations en nitrate est également mis en valeur, néanmoins la limite de potabilité (50 mg/l) est rarement dépassée.相似文献