Volumen 2 No. 1 (2011)

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Browsing Volumen 2 No. 1 (2011) by Author "DIUC"

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    Characterizatión of main external climate influences in rainfall and air temperature in the Paute River Basin - Southern Andes of Ecuador
    (Universidad de Cuenca, 2011-07) Mora, D. E.; Willems, Patrick; DIUC; Universidad de Cuenca; Dirección de Investigación de la Universidad de Cuenca
    Characterization of climate variability in the Andes mountain range needs special assessment as rainfall and temperature are extremely variable in space and time. This paper examines the anomalies of observed month rainfall and temperature data of respectively 25 and 16 stations, from the early 1960‟s to the 1990‟s and compare them against anomalies from different external climate influences in annual and 3-month seasonal block periods. The stations are located in the Río Paute Basin in the Ecuador‟s southern Andes. All stations are within the elevation band 1800 and 4200 m a.s.l. and affected by the Tropical Pacific, Amazon and Tropical Atlantic climate. The results show similar temperature variations for the entire region, which are highly influenced by the ENSO, especially during the DJF season. During JJA, the correlation is weaker showing the influence of other climate factors. Higher temperature anomalies are found at the high elevation sites while in deep valleys the anomalies are less significant. Rainfall variations depend, in addition to elevation, on additional factors such as the aspect orientation, slope and hydrological regime. Highest and most significant rainfall anomalies are found in the eastern sites.
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    Desempeño de modelos hidráulicos 1D y 2D para la simulación de inundaciones Lus Timbe
    (Universidad de Cuenca, 2011-07) Timbe Castro, Luis Manuel; Willems, Patrick; DIUC; Universidad de Cuenca; Dirección de Investigación de la Universidad de Cuenca
    Nowadays, the availability of high resolution Digital Elevation Models (DEMs) to represent the earth surface allows coupling of hydraulic models with Geographic Information Systems (GIS) to obtain the flood extent and water levels in floodplains. Many studies on flood mapping have been conducted using one or two dimensional (1D/2D) hydrodynamic models. Some authors affirm that 2D hydraulic models are the state of the art for river flood modeling. They have, however, the disadvantage that their application is constrained by the high requirements for data, hardware and software. 1D models are capable of modeling precisely the flow in main rivers, but are less accurate for modeling over bank flow. The aim of the investigation is to test the accuracy for river floodplain modeling comparing a quasi-2D approach using a 1D model with a full 2D approach. The models were tested for the river Dender in Belgium for three historical flood events.
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    Hydraulic assessment of waste stabilization ponds: comparison of computational fluid dynamics simulations against tracer data
    (Universidad de Cuenca, 2011-07) Alvarado, Andrés; Vedantam, Sreepriya; Durazno, Galo; Nopens, Ingmar; DIUC; Universidad de Cuenca; Dirección de Investigación de la Universidad de Cuenca
    The overall performance of a wastewater treatment plant is in addition to the effectiveness of the biokinetic processes controlled by the flow dynamics. A wide used technique to characterize the water flow dynamics is the use of tracers. At full-scale tracer experiments in wastewater treatment plants provide insufficient information to completely grasp the flow dynamics. Additionally results are often biased by uncontrolled external factors. As alternative, computational fluid dynamic (CFD) models for performance analysis of existing and the design of new wastewater treatment plants have been increasingly used over the last decade. The paper presents the results of a tracer experiment against the output of a CFD model with application to a 7 ha large maturation pond. The tracer study was conducted with the fluorescence dye Rhodamine WT using the stimulus response technique. The three dimensional CFD model was built considering a variable density distribution of spatial grids based on the specific characteristics of the system. For the unsteady flow simulations the turbulence model k- was adopted. Residence time distribution (RTD) generated by both approaches were compared and showed fairly good agreement. The velocity and turbulence profiles of the CFD model were compared with experimental data confirming, although the high computational demand, the robustness of the used CFD model.
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    Metales pesados en humedades de arroz en la Cuenca baja del Río Guayas
    (Universidad de Cuenca, 2011-07) Pozo, Wilson; Santafeliu, Teófile; Carrera, Gloria; DIUC; Universidad de Cuenca; Dirección de Investigación de la Universidad de Cuenca
    In the lower basin of Guayas, more in particular in the wetland area, the rice is cultivated on 350.000 ha. An area of 100 km2, covering both sides of the tributary river Babahoyo, situated in the cantons Samborondón and Yaguachi, was selected to study the presence of heavy metals in the top soil and plants. Soil samples were collected in 26 sites, whereas plants were sampled in 5 sampling stations. The concentration of heavy metals in the top soil was related to soil edaphological properties and the concentration in the rice plants, using multivariate analysis. At each site 12 variables were measured resulting over the 26 sites in the following average values: MO 4%, clay 32,7%, loam 49,8%, sand 17,5%, pH 6,6, CE 7,9 mS m-1, metal concentration in mg kg-1 Cu 48,8, Fe 8.734, Mn 343, Zn 34, Hg not detected, Cd 0,15 y Pb 4,4. Statistical analysis revealed that 40,7% of the spatial variability in heavy metals in the top soil is explained by the first two principal components, loam and clay (CP1) and clay and cadmium (CP2). In addition, the 26 sites could be grouped in 6 distinct classes at an euclidian distance of 3,22. Based on the concentration the heavy metals in the top soil rank from high to low as follows: Fe > Mn > Cu > Zn > Pb > Cd and Hg not detected. The concentration of lead in the sites where also the lead concentration was measured in the rice plants, 5 locations in total, ranged
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    On the assesment of water resources model predictions
    (Universidad de Cuenca, 2011-07) Vázquez Zambrano, Raúl Fernando; DIUC; Universidad de Cuenca; Dirección de Investigación de la Universidad de Cuenca
    The analysis of the most commonly used measures of hydrological/hydraulic model performance was herein carried out by means of their statistical examination and illustrative modelling applications. In doing so, the model performance indexes were classified in two groups, according to the type of error (or residual) that those indexes are measuring: (i) statistics measuring the average systematic error (model bias); and (ii) statistics measuring the average combined systematic and random discrepancies among simulations and observations. The reader can in this way easily select a set of unrelated statistics to report on model performance. The manuscript addresses as well the main pitfalls of some of the most popular statistics used in scientific literature and suggests some approaches to overcome such potential pitfalls when addressing model performance.