Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

La dinámica y disponibilidad del recurso hídrico es un aspecto fundamental en el estudio de las cuencas hidrográficas. Desde la perspectiva temporal, el recurso hídrico está relacionado con la precipitación, que varía con los eventos hidrometeorológicos, mientras que espacialmente, está relacionado en gran medida con el uso de la tierra o la cubierta vegetal. Se investigaron los cambios en la escorrentía superficial del río Duero basin, México, utilizando el modelo SWAT. The input data for the model include climatic variables, soil properties, topography, and four periods of land use map. Las estimaciones de escorrentía del SWAT se compararon con los datos de caudal del Banco Nacional de Datos de Aguas Superficiales. En 1983 se observó un registro elevado de escorrentía de hasta 30 Dam3 (decámetro cúbico) en los municipios de Tangamandapio y Tangancícuaro, que probablemente se asoció con la tala de bosques desde la década de 1970; también se observó una disminución de escorrentía a 10 Dam3 en 2000, lo que probablemente refleja la práctica de conservación del manejo forestal. Las simulaciones para 2011 y 2014 indican alta escorrentía en el municipio de Chilchota debido a la modificación de sus áreas forestales y agricultura tradicional para acomodar el cultivo del aguacate y bayas.

The sustainability of ecosystems and economic activities depend significantly on the availability of water, which can be affected by its temporal variability. Colombia is one of the countries that suffers high temporal variability of the water resource because of global, regional, and local phenomena. One of the macro-climatic events that alter the water regime is ENSO. Its impact on lotic water bodies is well known, while the effects on lentic systems are unknown. In this study, a methodology, which integrates climatic analyses with remote sensing studies, was designed to evaluate the relationship between the expansion and contraction of lotic bodies under the ENSO event, verified in four welt lands (ciénagas) in the department of Córdoba. The results showed that the dynamics depend up to 60 % on this macro-climatic event. The methodology developed can be considered as a tool for environmental planning of the territory around the lagoon systems, since it allows estimating buffer zones.

Hydraulic works such as reservoirs, dikes, bridges, and urban drainage, are planned, designed, built, and reviewed (the existing) under a hydrological safety, based on the Design Floods. Such estimates of the maximum annual flow associated with low probabilities of exceedance, are called Predictions and are obtained through the so-called frequency analysis of floods. This technique consists of selecting a probability distribution function (PDF), which represents the sample of available flows, and based on such a model prediction is sought. When the record of floods is reduced, unreliable, or does not exist at the site of interest, regional analysis is used; an approach that extends the length of available records to reduce errors in estimates and allows estimating predictions in locations without data. In this study a contrast was made between local and regional predictions; the latter was obtained according to two different methods in the Hydrological Region No. 10 (Sinaloa), Mexico. In the first method, the records of maximum annual flows and their respective dates of occurrence were processed, to define the regions of influence each. For the second method, which is detailed, the same hydrometric information is used and the flood index method, using the TCEV (two-component extreme value) distribution as a regional PDF, is suggested for flow records that were generated by two physically different mechanisms and cannot be separated. The exposed regional method is much simpler and leads to fairly approximate predictions by deficit and more accurate by excess, according to the relative errors evaluated. Therefore, its systematic application is recommended in other hydrological regions of the country.

El recurso agua es limitado en la zona norte de Chile por tratarse de una zona árida, de ahí la importancia de estudiar si en ellas se están verificando cambios hidrológicos que pudiesen alertar sobre un incremento de tal situación. Para ello, se estudiaron las tendencias de los caudales punta (caudal máximo instantáneo) de la Región de Coquimbo, a través de la prueba estadística de Mann-Kendall (5 % error) en el periodo 1984-2014 (periodo reciente) y en un segundo periodo extendido (1976-2014). Los resultados indican que para los caudales punta anuales en ambos periodos todas las series presentan tendencia a disminuir, pero un 80 % lo hace significativamente en el periodo 1984-2014, y un 29 % en el periodo extendido. En tanto, para los caudales punta mensuales, en el periodo 1984-2014, un 99.2 % de las series manifiesta una tendencia a disminuir, donde 45.8 % lo hace de forma significativa. Sin embargo, en el periodo extendido, un 73.8 % de series presenta tendencia a disminuir, pero sólo 11.9 % lo hace de manera significativa. Este fenómeno de la baja en las tendencias negativas y significativas al incorporar años anteriores a 1984 demostraría que dichas situaciones se han producido anteriormente. Por último, esta variación en el nivel de significancia al considerar diferentes longitudes temporales estaría evidenciando un proceso cíclico que influencia el comportamiento de los caudales punta.

In this research, the kinetics of the reduction of the initial turbidity (1455 NTU) of wastewater from a tannery industry was evaluated by applying direct bioflocculants prepared from the algae Chondracanthus chamissoi (alginate) and the molts of the crustacean Emerita analoga (chitosan). The biological precursor material was collected on Lima, Peru's beaches; from this material, fibrous alginic acid was produced, and later sodium alginate. The processes of demineralization, deproteinization, and subsequent deacetylation were used to obtain chitosan from crustacean molts. The effect of pH, the doses of bioflocculants, and the equilibrium time of the process were evaluated. In addition, the kinetic order of the flocculation rate was determined using the jar test. The results indicated a turbidity removal of more than 99 % within the first 30 minutes for doses of 0.2 to 2 g/l of flocculants and acid pH (equal to 4); no significant differences were recorded at different pH values (4-12) and doses (0.2 to 2 g/l). The linear adjustment between flocculation time and turbidity generated significant first-order kinetic equations for both flocculants with rate constants k1 of the order of 10-4 (1/NUT.min) and reduction times of half of particulate matter (average life: τ1/2) less than 10 minutes. This can be considered as a criterion to measure the efficiency of the direct flocculation process in the treatment of tannery industrial waters.

Drought risk reduction and its direct and indirect impacts have gained worldwide relevance during the last decades. This paper presents a review of the basic conceptual and methodological tools to analyze the drought risk in a given system. The fundamental components of risk are described, conceived primarily as a function of hazard (or specific danger, which in this case is the drought phenomenon); exposure (people, property, livelihoods, and systems that are subject to potential damage and loss due to hazard), and vulnerability (represented by the socio-economic and environmental conditions of the system that make it susceptible to suffering damage). The concepts and definitions associated with these components are explained and the most usual mathematical methods and models for calculating them are presented. It is concluded that, given the great diversity of approaches, concepts, and methods to determine drought risk, it is at the discretion of the researcher or evaluator the selection of the most appropriate depending on the approach adopted, the information available, and the objective or investigation context.

Los cambios observados en el clima durante las últimas décadas han generado una creciente inquietud popular, especialmente en el mundo científico, lo que ha propiciado una serie de investigaciones sobre las causas y posibles consecuencias del cambio climático. Éste es un tema de gran interés a nivel mundial, incluyendo México. La región denominada altiplano potosino se localiza en la parte noroccidental del estado de San Luis Potosí, México, con un área de 29 119.80 km²; tiene una precipitación anual inferior a los 400 mm y temperatura media anual de 17.5 °C. El agua subterránea es la principal fuente de abastecimiento, ya que las escorrentías superficiales son limitadas. El objetivo de este trabajo fue realizar un análisis de series de tiempo de los registros históricos de la precipitación y la temperatura en las estaciones meteorológicas ubicadas en la región de estudio en el periodo 1975-2015, para identificar tendencias y patrones espaciales y temporales. Para ello, se utilizó la prueba estadística no-paramétrica de Mann-Kendall. Los resultados indican tanto incrementos como decrementos en las tendencias anuales y mensuales para las variables analizadas. Dichas tendencias sugieren comportamientos locales. Con respecto a la precipitación, se presentan incrementos en primavera y verano mientras que tienden a disminuir en otoño. Con respecto a la temperatura, se detectó una mayor variabilidad en las tendencias (anuales y mensuales); hay un mayor reflejo en la variabilidad anual, sustentada por los cambios mensuales; o en su caso, existen variaciones mensuales que aún no se ven reflejadas en una tendencia anual.

In the recent hydroelectric power plants built in Mexico (P.H. El Cajón, P.H. La Yesca, and Grijalva River tunnels), the diversion tunnels have been designed with a combination of materials: hydraulic concrete in its template and concrete cast in its walls and vault, which allows to reduce hydraulic losses and get a greater discharge capacity to guarantee the hydrological safety of the dam during the build time, in addition to achieving considerable cost savings. To monitor this capacity, several instrumentation projects have been carried out, recording the hydraulic variables in different sections, in addition to estimating the representative parameter of the composite roughness. This article relates how estimates the composite roughness parameter in diversion tunnels, in a case study: “Communication tunnels of the Grijalva River”, upstream of the Penitas Hydroelectric Power Plant, using hydraulic instrumentation to measure, among other variables, the speed in the area near to the wall. And applying the boundary layer theories of Nikuradse and Prandtl-Von Kármán to determine the equivalent roughness in the walls, as well as the review of 17 empirical equations to finally obtain the representative composite roughness of the tunnels.

Los residuos de la industria de la caña de azúcar representan uno de los principales agro-residuos. A menudo se consideran como basura y se pueden utilizar como materia prima barata para obtener carbón activado (CA). Por otra parte, el agua residual doméstica contiene residuos de grasas y aceites causantes del taponamiento de las tuberías; se puede lograr la adsorción de estas sustancias con carbón activado. En este trabajo se obtuvo CA a partir de residuos de bagazo de caña de azúcar mediante un método simplificado de dos pasos: activación química con H3PO4 y pirólisis a 973 K. La caracterización textural y estructural fue por fisisorción N2, microscopía electrónica de barrido (SEM) y difracción de rayos X (RDX). El carbono obtenido (SBET de 914 m2g-1) mostró una estructura análoga al grafito y una superficie microporosa característica de los carbonos activados. El carbono sintetizado se evaluó en la adsorción de grasas y aceites de aguas residuales domésticas. Los resultados mostraron el valor agregado que se obtiene del bagazo de caña para eliminar eficientemente grasas y aceites de aguas residuales, ya que después de ocho horas se encontró que su CA adsorbió el 94 % de las grasas y aceites contenidas en las aguas residuales, lo cual es similar a la adsorción de un CA comercial (96 %). También se evaluó la cinética de adsorción con las ecuaciones de pseudo primer orden, pseudo segundo orden e intrapartícula; los datos experimentales mostraron un mejor ajuste con el modelo de pseudo segundo orden.

One of the objectives of hydrological studies is the estimation of the annual runoff volume (VEA, for its name in Spanish) of watersheds without gauging. Such data is basic in the design of reservoirs. In this study, the estimation is provided through regional frequency analysis, based on the Runoff Index method. This approach was applied in the Hydrological Region No. 10 (Sinaloa), Mexico, for which 22 VEA records were processed, with amplitudes that varied from 24 to 57 years. Through the Discordance Test, three records were eliminated. Regional hydrological homogeneity was verified with the remaining 19 records and three statistical techniques: seasonality indices, linearity of ordinary moments, and linear regression between probability-weighted moments. The tests of loss of homogeneity of each record led to the elimination of four, due to their ascending linear trend. The 15 remaining records were processed in a dimensionless way, by dividing their data over their annual mean runoff volume (VEMA) and they were concatenated with the stations-years method, forming a series of 539 data. Three probabilistic models were applied to obtain the regional growth curve: Pearson type III, Log-Normal, and Potential Transformation; choosing the one with the smallest standard error of fit. The scaling of the regional Log-Normal distribution was achieved with a logarithmic relationship between the VEMA and the basin area of the processed records. In the Conclusions section, the established procedure is detailed and the importance of the results to generate synthetic sequences of VEA is highlighted (which are equally probable to occur). Therefore, the systematic application of the Runoff Index procedure as a method of estimating the VEA in other regions of the country is recommended.