HIDROGRAMA UNITÁRIO INSTANTÂNEO GEOMORFOLÓGICO APLICADO A BACIAS DESPROVIDAS DE DADOS HIDROLÓGICOS

Several watersheds don’t have precipitation data, it isn’t allowing to obtain flow through the conventional method of hidrograma unit. Thus, this study aimed to obtain hidrogram of the Basin of Ribeirão Salobra-MS, from geomorphological features. For this, a mathematical model was developed, based on probabilistic concepts of geomorphological Instant Hidrograma Unit, which used data from topographic maps. The simulations were developed for two runoff speeds, calculated from different equations of concentration time. It appears that the flow speed is directly proportional to the peak flow and inversely proportional to the time base. The model can be used as initial estimate of flow data for watersheds not monitored by hydrological parameters. However, it is important to validate it with hydrological data collected in the basin under study. Keywords: geomorphology, hydrographic basin, geomorphological instantaneous unitary hydrograph.Diversos locais permanecem desprovidos ou com dados escassos de precipitação impossibilitando a obtenção de dados de vazão por meio do método convencional do hidrograma unitário. Deste modo, este trabalho teve por objetivo a obtenção de hidrogramas da Bacia do Ribeirão Salobra-MS, a partir de suas características geomorfológicas. Para tanto, foi desenvolvido um modelo matemático, baseado em conceitos probabilísticos do Hidrograma Unitário Instantâneo Geomorfológico (HUIG), que utilizou dados provenientes de mapas topográficos. As simulações foram desenvolvidas para duas velocidades de escoamento, calculadas a partir equações distintas de tempo de concentração. Verifica-se que a velocidade de escoamento é diretamente proporcional a vazão de pico e inversamente proporcional ao tempo de base. O modelo pode ser utilizado como estimativa inicial de dados de vazão para bacias hidrográficas não monitoradas por parâmetros hidrológicos. No entanto, é importante sua validação com dados hidrológicos coletados na bacia hidrográfica em estudo. Palavras-chave: geomorfologia, bacia hidrográfica, hidrograma unitário instantâneo geomorfológico

EVALUATION OF GEOMORPHOLOGIC INSTANTANEOUS UNIT HYDROGRAPH METHOD IN FLOOD HYDROGRAPH SIMULATION

Comparing with other models, the geomorphologic and geomorphoclimatic hydrographs are the most efficient methods to estimate flood discharge

Comparison of hybrid regression and multivariate regression in the regional flood frequency analysis: A case study in Khorasan Razavi province

Background: Magnitude, rate and frequency of the stochastic and unexpected events are of great significance and importance in hydrology. Nowadays, for economic planning of the projects, the use of analytical methods of unexpected events in hydrology is unavoidable. The aim of this study was to compare hybrid regression and multivariate regression to estimate flood peak discharge in the province of Khorasan Razavi and in the selected water measured stations. Methods: For this purpose, 19 hydrometric stations were selected and analyzed. In the first step, the rate of peak discharge was estimated with different return periods and by selecting the best regional distribution (lognormal distribution type ΠΙ). In the next step, independent and important variables including area, mean annual rainfall, the average height of the watershed and its slope were determined using functional analysis and using SPSS software version 22. Then, two hydrologically homogeneous regions were determined by homogeneity test using cluster analysis, and accordingly, two models were presented for the whole area and also for homogeneous areas. To compare and evaluate the accuracy and efficiency of the estimated models, the rates of discharges were estimated and compared with observational rates using three control watersheds. To compare models, it was used from the average absolute values of the relative error index. Results: It was revealed that the hybrid method was more accurate than the multivariate regression method in the return period of 50 years and provides better results of flood discharges for the area. Homogenous areas had a higher coefficient of determination (R2) and lower relative standard error (RSE) compared to the whole area. It was also revealed that with increase of return period, the rates of R2 decreased but the rates of relative standard error increased. Conclusion: The accuracy of multivariate regression and hybrid methods was the same in the 25-year return period. In the present study, the importance and necessity of homogenous areas compared with the model of the whole area are completely evident. Keywords: Floods, Regression analysis, Khorasan Razavi province, Statistical distributions, Hybrid regressio

Flood hazard zoning using geographic information system (GIS) and HEC-RAS model (Case study: Rasht City)

Rivers are important water resources for human life, but sometimes cause irreparable damages. The flood plains are fertile terrains which are endangered by flood. Flood hazard mapping is one of the basic methods in flood fighting. In order to decline flood damages, the simulation of the hydraulic behavior of the rivers during flood occurrence is very important. In this study, areas that are flooded were zoned along Siahrood and Goharrood rivers (Rasht City, northern Iran). The rivers bed and banks terrains of Goharrood and Siahrood were simulated using HEC-GeoRAS extension and digital map (scale: 1000). Pick discharges with different return periods were estimated using stochastic analysis. HEC-RAS software and geographical information system were applied for simulating the hydraulic behavior of the rivers and providing flood zoning map. The GIS was an efficient tool for data-processing and mapping stages. Finally, the flood zones associated with 2, 10, 25, 50, 100 and 200 years return periods were mapped and necessary analysis were conducted during the present research. The results showed that some parts of Rasht City (river bank terrains) are endangered flood hazard

Regionalization with hydraulic geometry and fractal : case study with geomorphologic instantaneous unit hydrograph

O Hidrograma Unitário Instantâneo Geomorfológico (GIUH) é gerado a partir de dois componentes, um em relação à geomorfologia da bacia hidrográfica e outro em relação às condições hidráulicas de movimento da gota d’água ao longo do canal. A partir desta constatação o objetivo deste trabalho é determinar a relação entre velocidade média no fluxo dos canais (v) e comprimento de canais para cada bacia, utilizando valores de velocidade medidos em campo e precipitação efetiva de sete eventos, distintos, gerando GIUH calibrados. Com os valores de velocidade calibrados para cada bacia, relacionou-se de forma linear e potencial, através de regressão multivariada, os parâmetros de Precipitação média anual (Pma), Geometria Hidráulica (GH) e Geometria Fractal (GF) e determinando uma equação regionalizada de v. Os GIUHs determinados a partir de Pma, GH e GF apresentaram bom desempenho quando comparados com os hidrogramas observados, comprovando que esta metodologia se adequa para representar e estimar vazões em locais com poucos dados e até mesmo sem dados.The Geomorphological Instantaneous Unit Hydrograph (GIUH) is generated from two components, one in relation to the geomorphology of the watershed and the other in to relation the hydraulic conditions of drop water moment along the channel. From this observation, the objective of the present study is to de-termine relationship between water flow velocity and length of channels for each basin, using velocity values measured in the field, and effective rainfall of seven distinct events, it was generated calibrated GIUH. With the v values for each basin were related linearly and potential, multivariate regression, the annual rainfall (Pma) parameters, Hydraulic Geometry (HG) and Fractal Geometry (FG) determining a regionalized equation v. The GIUHs determined from Pma, GH and GF performed well when compared to the observed hydrograph, which proves that this methodology is suitable to represent and estimate flows

Upscaling of lateral groundwater flow processes in watershed models

Hydrologic models are essential tools for hydrologists and water resources engineers. However, there is a critical gap between our knowledge of the appropriate model representation of physical processes at the point scale and at the watershed scale. Due to the ubiquitous presence of heterogeneity, this scale disconnect can have significant implications for practical watershed modelling. Closing this gap requires the identification and implementation of appropriate upscaling approaches. Upscaling refers to the derivation of relationships which translate small scale process descriptions into constitutive relationships that are applicable at larger scales. While several approaches in the literature have been successful in generating such relations for vertical flow (i.e., laterally independent) processes, such as infiltration or evapotranspiration, attempts to address lateral flow processes have been limited. This work establishes upscaling relationships and identifies critical watershed-scale landform controls for lateral subsurface stormflow, being the lateral transfer of water through the saturated subsurface of a hillslope into a surface water network during a recharge event. This work also establishes a novel and comprehensive literature review synthesizing decades of applied upscaling work in the hydrology literature. This review is intended to provide a practical starting point for future research into upscaling approaches in computational hydrology. Subsurface stormflow is here characterized by the hillslope-storage Boussinesq (hsB) equation at the hillslope scale, and manifests as an aggregate recession curve at the basin sale. A surrogate model developed herein, the hsB Proxy, rapidly provides high-quality approximate solutions to this non-linear governing equation, and thus enables the application of the equation across 50 basins composed of hundreds of hillslopes. Upscaling relationships are generated from the aggregate recession behaviour in these basins in response to a recharge time series. This work describes the development of the hsB proxy, and the associated development of novel upscaling relationships that capably reproduce the aggregate recession behaviour of a basin in response to a recharge time series, using only the distribution of hillslope-scale properties as input. The insights thus generated provide a new, explicit connection between the topographic characteristics of a basin, the history and magnitude of recharge, and the large-scale recession response. These relationships allow hydrologic models to include the insights of detailed hillslope drainage physics without the associated computational cost

DISEÑO DE HERRAMIENTA HIDROLÓGICA COMO APOYO A LOS SISTEMAS DE ALERTA TEMPRANA ANTE INUNDACIONES

Las inundaciones son uno de los fenómenos naturales que se presenta con mayor frecuencia alrededor del mundo afectando a gran número de personas y causando cuantiosos daños. México no es la excepción pues, dada su ubicación geográfica, cada año se ve afectado por fenómenos meteorológicos que afectan gran parte de su territorio. Como consecuencia, las inundaciones son uno de los desastres naturales que más afectan a su población. Por tal razón, la preparación ante estos desastres naturales es esencial para una respuesta oportuna que permita salvaguardar vidas humanas y bienes materiales, además de la rápida recuperación por parte de la población afectada y las autoridades. Es en este sentido que la presente investigación tiene como objetivo la implementación de una herramienta hidrológica que sirva de apoyo para la construcción de sistemas de alerta temprana ante inundaciones, mediante el acoplamiento y automatización de paquetes informáticos de aplicación hidrológica, hidráulica y sistemas de información geográfica. La implementación de herramientas hidrológicas incluyó dos modelos lluvia-escurrimiento, HEC-HMS Y CEQUEAU. Modelos ampliamente conocidos y utilizados, cuyas capacidades ya han sido demostradas en numerosas investigaciones, además de la implementación de un modelo de hidrograma unitario espacialmente distribuido. La parte hidráulica incluyó la implementación del modelo HEC-RAS para la modelación del tránsito de avenidas producto de las modelaciones hidrológicas. Las pruebas se desarrollaron en la cuenca del río La Sierra (Chiapas-Tabasco). La aplicación de los desarrollos productos de esta investigación demuestra la factibilidad de acoplar herramientas hidrológicas e hidráulicas con un sistema de información geográfica para la evaluación de riesgos por inundación, monitoreo de indicadores como precipitación y la predicción del comportamiento hidrológico e hidráulico de una cuenca con base en la modelación matemática

Instructed fear stimuli bias visual attention

We investigated whether stimuli merely instructed to be fear-relevant can bias visual attention, even when the fear relation was never experienced before. Participants performed a dot-probe task with pictures of naturally fear-relevant (snake or spider) or -irrelevant (bird or butterfly) stimuli. Instructions indicated that two pictures (one naturally fear-relevant and one fear-irrelevant) could be followed by an electrical stimulation (i.e., instructed fear). In reality, no stimulation was administered. During the task, two pictures were presented on each side of the screen, after which participants had to determine as fast as possible on which side a black dot appeared. After a first phase, fear was reinstated by instructing participants that the device was not connected but now was (reinstatement phase). Participants were faster when the dot appeared on a location where an instructed fear picture was presented. This effect seemed independent of whether picture content was naturally fear-relevant, but was only found in the first half of each phase, suggesting rapid extinction due to the absence of stimulation, and rapid re-evaluation after reinstatement. A second experiment similarly showed that instructed fear biases attention, even when participants were explicitly instructed that no stimulation would be given during the dot-probe task. Together, these findings demonstrate that attention can be biased towards instructed fear stimuli, even when these fear relations were never experienced. Future studies should test whether this is specific to fear, or can be observed for all instructions that change the relevance of a given stimulus

Hydrogeological and hydrogeochemical investigation of a Precambrian basement aquifer in Bugesera region (Burundi)

This study clearly shows that Bugesera region has genuine groundwater potential which could be circumscribed and tapped in order to provide enough drinking water to the inhabitants of the area. Thus, this study recommends further investigations and measures, including, geophysical investigations coupled to reconnaissance drillings, the installation of a network of piezometers to monitor the groundwater level variation, measurement of the discharge rate and water level fluctuation in the complex of marshlands and lakes, monitoring of groundwater quality and further pumping tests in order to refine the distribution of hydraulic parameters in the study area