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

Droughts are hydrometeorological hazards that are characterized by an abnormal and persistent humidity deficit. In the last years, this hazard  has been present more frequently and with more severity levels, producing negative impacts on the ecosystem, agriculture, livestock, and  society. Therefore, its monitoring and forecast, must be part of integral planning, preparation, and mitigation of its adverse effects at local, regional, and national levels. In Mexico, most of the drought studies are focused on characterization and analysis. Thus, in this research, we evaluated the application of artificial neural networks (ANN) to forecast the meteorological droughts in the medium and high parts of the Sonora River watershed. SPI and SPEI index were used, on scales of 3, 6, 12, and, 24 months, for the 1974 to 2013 period of years. Forecast results showed that ANN has a satisfactory level of prediction, with an average determination coefficient (R2) in the validation phase, of 0.76. It was observed that the statistical efficiency of SPEI was better than that of SPI, and that this efficiency increased with the longer temporal scale; maybe because in a short term, climate variability is greater.

The lipid extract of fruits of the royal palm Cubana (Roystonea regia), developed at the National Center for Scientific Research (CNIC), will be used in the treatment of benign prostatic hyperplasia (BPH). The product is a liquid oil to be encapsulated in soft gelatin capsules. In Cuba, there was no industrial plant for soft capsule production; a plant was built for this purpose, which was necessary for the previous study of the wastewater model. A treatment scheme to laboratory scale of three stages: Trap of fat, primary sedimentation, and ozonation was evaluated. In the first two stages, hydraulic retention times of 15, 30, and 45 minutes were studied, obtaining the best condition for 30 minutes. The ozonation process was carried out with an experimental design 23, with two ozone concentrations in the gas (40 and 60 mg O3/l), two gas flows (10 and 20 l/h), and two pH values (3 and 7); the ozonation time was 30 min. Ozone doses of 330, 500, and 660 mg O3/l were applied. Statistical analysis showed that the best results were obtained with ozone concentration: 60 mg O3/l; gas flow: 10 l/h, and pH: 3. The combination of the treatment stages allowed achieve a total efficiency of reduction of COD (51.6 %), BOD5 (64.7 %), ST (21 %), SSed (100 %), fats and oils (79.3 %), detergents (91.6 %), nitrogen (30.1 %), phosphorus (93.1 %), turbidity (85.8 %) and color (90.1 %), guaranteeing compliance with the Cuban NC standard 27: 2012.

The floods in our country every year cause damage and endanger the reservoirs. Therefore, its hydrological dimensioning is based on the hydrograph of the design flood, and its most straightforward estimation is based on the joint frequency analysis of the annual peak flow and volume. In this study, the bivariate general extreme values distribution (GVEb) was adjusted to the record of the 55 annual floods at the La Cuña hydrometric station on the Río Verde of Hydrological Region No. 12-3, Mexico. This study encompasses the following nine stages: (1) selection and testing of annual records; (2) verification of the randomness of the records; (3) estimation of the joint empirical probabilities; (4) adjustment of the GVEb function through the maximum likelihood method; (5) validation of the GVEb function; (6) ratification of GVE marginal functions; (7) verification of probability constraints; (8) estimation of hybrid univariate design events, and (9) estimation of joint design events and selection of the critical subgroup. In stage 1, a simple test is applied based on the shape parameter of the marginal GVE. Stage 2 is carried out based on the Wald–Wolfowitz Test. In stage 4, the Complex algorithm is used. Stages 5 and 6 use the Kolmogorov-Smirnov Test. In stage 9, the graphs of the joint return period of type AND are used. Finally, conclusions are formulated, which highlight the maximization approach adopted and the advantages of the bivariate joint frequency analysis through the GVEb.  

The unbridled forces in play that are undermining our social fabric (climate change, pandemics, poverty) erode societies’ capabilities for resilience. Hence there is an urgent need to evaluate the strengths of institutional and community systems in vital areas such as water management. This research analyzed part of the social structure responsible for generating scientific knowledge pertaining to water resources in Mexico, taking into account the organizational patterns pre-established by experts, in order to determine the strengths and weaknesses of the existing structures. We used the social networks approach, which revealed a system permeated by patterns of social centralization that limit knowledge sharing and social cohesion and produce very little innovation within the water resources investigation networks in Mexico. We conclude that it is necessary to expand the training and managing of intellectual capital in various areas of knowledge related to water resources, especially those that are relevant for recuperating environmental sustainability.

The design peak flow determination of a hydraulic work is conditioned by the hydrometric and pluviographic information available and the physiographic characteristics of the basin under study. The use of empirical hydrological models implies significant uncertainty if it is considered that the design storm's return period differs from the design flood's return period. When downstream hydrometric data is available, transferring the maximum runoff to the project site is necessary. For this procedure, areas, rainfall volumes, or runoff coefficients are commonly used; however, these procedures are invalid when important tributaries are incorporated between the study sites. Therefore, a semi-distributed conceptual methodology is proposed to simulate maximum average daily hydrographs in the present work. The model, complemented with a parameterization of peak flows from average daily flows, allows the transfer of maximum annual floods from a hydrometric station to the site of a hydraulic project. The determination of a potential flow associated with each Thiessen polygon was conceptualized. For the hydrological modeling and translation of the maximum daily mean hydrographs. The potential flow was defined from the rainfall volume and the weighted average delay time of the sub-basins that coincide in each polygon. The preceding made it possible to relate the geospatial influence that precipitation records have on the production of runoff volumes with estimating the hydraulic conduction time of the different coincident channels.

Rainwater harvesting is an alternative that can contribute to solving water scarcity problems. However, since the design of a Rainwater Harvesting (RWH) system is influenced by several variables, the correct selection of the appropriate storage tank capacity could be a difficult task for people who do not have basic hydrological knowledge, like the proprietors of a house, or members of civil organizations. The objective of this study is to develop regional models to estimate the optimal volume of rainwater collection tanks in communities of the Upper Mixteco River Basin (UMRB) in Oaxaca, Mexico. Based on the analysis of daily rainfall data from 12 weather stations, and the application of the water balance method, simulations of the tank operations of different capacities were carried out for a number of users, as well as catchment areas and demand fractions. As a result, the spatial variation of the optimal tank capacities was obtained, which, together with the annual mean rainfall data, were used to obtain exponential regression equations. It was determined that the capacities of the tanks will be greater in localities in the north of the basin, where it rains less, while, towards the southwest, smaller capacity tanks are required. On the other hand, the regional equations will allow to quantify in a practical way, the capacity of the tank for the functional design of the RWH system in the UMRB.

Las costas del Mediterráneo occidental han sido afectadas por tsunamis en el pasado y pueden oponerse a este riesgo en cualquier momento. El margen del norte de África es una zona principal propensa a terremotos destructivos que a veces desencadenan tsunamis y plantean un peligro potencial para la vida humana y los bienes de las ciudades costeras. El presente estudio consiste en un modelado numérico de una ola de tsunami que actúa sobre las costas argelinas para un terremoto de magnitud Mw 7.55 con longitud y anchura de la falla (73.3 x 29.9 km) y un deslizamiento vertical de 3.5 metros. Este modelado numérico basado en un código de cálculos desarrollado sobre la base de las fuentes de modelos hidrodinámicos bidimensionales Telemac-2D permite mapear las alturas de las ondas y las velocidades máximas generadas por el Tsunami. La simulación indica que los valores máximos para las alturas de superficie son de aproximadamente 1.2 metros y de 30 a 50 m/s para las velocidades de flujo. Los resultados obtenidos muestran que el área de estudio está más expuesta al riesgo de inundación por un tsunami que causa daños significativos a la infraestructura básica. Los resultados obtenidos se exportan a una plataforma de información SIG que permite el desarrollo de una cartografía ilustrativa de las características hidráulicas de la ola generada por el tsunami, y de la hora de llegada y desplazamiento de la inundación con la ubicación de zonas vulnerables a la inundación. Esto constituye una herramienta de toma de decisiones para los tomadores de decisiones de planificación del uso de la tierra y también un medio de mitigación del riesgo en el caso de los posibles terremotos que causan tsunamis en la región.

The tracers as a method of measuring and characterizing the evolution of natural flows, in addition to providing information on the dynamics (advection) and dispersion as "local" phenomena themselves, can give additional, dense information on the global conditions (far from the point of measurement) under the thermodynamic connection that is established between all the points of the system, when there is a steady-state in the channel. As has been widely studied since the second half of the last century, this condition of dynamic equilibrium (steady-state) in natural flows, for phenomena that do not present pronounced irreversibility (linear region of irreversible thermodynamics), implies a series of remarkable features that simplify the interpretation of the complex phenomena of turbulent currents, and thus of the superimposed dispersive processes. Within this approach, a state function, Φ(U, E, t), dependent on the mean flow velocity, the longitudinal dispersion coefficient, and time, is defined that describes the evolution of the tracer cloud, such that in its approximate quality of thermodynamic potential, it allows one to discover and pinpoint certain particularities of the phenomenon. In this paper, the characteristics and practical applications of these principles are explored. It also includes a heuristic analysis of the so-called direct functions rq(F) and inverse rq(F)-, auxiliary to the state function F(U,E, t), which are used for the interpretation of the centroid time, as well as the longitudinal and transverse diffusion-dispersion coefficients employing these functions were applied experimentally in the old stream of the city of Bogotá, “La Vieja”, presenting good agreement with the theoretical references. This topic is intended to provide a theoretical and practical tool to fully understand these processes, which are of great interest for the modeling and control of water pollution.

A thorough understanding of the interaction between the different components, that integrate all the phases of the hydrological cycle, is crucial and of vital importance in the use, conservation and protection of water. In urban environments, quantification of water balance components becomes particularly challenging. This study presents the spatial analysis of the sustainability of the San Salvador aquifer, a typical urban aquifer, which provides part of the water supply of the San Salvador Metropolitan Area (AMSS) in conjunction with three water import systems. Thus, the hydrogeological system and its flow systems have been characterized, likewise the components of the water balance have been identified, refined and quantified, defining the inputs, outputs and returns to the system. At the same time, the water balance equation has been proposed for the aquifer based on these components. Results show that the San Salvador aquifer is in an "apparent state of sustainability" that is supported by urban recharge, which represents multi-million-dollar annual pumping costs. That money could be reoriented to minimize water system leakage as well as to reduce withdrawals in the aquifer. Thus, the volume of water saved could be used to improve the water supply to the AMSS, store a reserve to face dry years or the recovery of dependent ecosystems. Additionally, the urban development of the northern slope of the San Salvador volcano, which reflects the areas with the highest water availability, must be carried out with caution since it entails a reduction in groundwater recharge. This would imply a decrease in base flow of the San Antonio and El Ángel rivers, which represent important sources of water supply for the AMSS users.

In this thoughtful theoretical essay, we developed a discussion regarding the assessment of learning in the process of training for care in Nursing in Collective Health throughout the supervised internship. We had conversations with the authors of Collective Health and of the assessment of learning by competencies, mainly those involved in medicine, who were pioneers in this debate, using the hierarchical-conceptual model of assessment by competencies proposed by George Miller. We sought to make a contribution by presenting the possibilities of methods, tools and procedures for the assessment of learning in summative or formative contexts, and the perspectives and tendencies of the assessment of the teaching-learning process in the field of Nursing. We verified that the assessment by competencies needs to be more discussed in order to be in line with the ongoing syllabus changes and the demands for the training of professional profiles that is in accordance with the needs and principles of the Unified Health System (Sistema Único de Saúde, SUS, in the Portuguese acronym).