This study is focused on the evaluation of selected rainfall-runoff episodes in terms of temporal and spatial distribution of rainfall and runoff in the upper basin of the Blanice River. HEC - HMS model with two variants of spatial discretization was used to achieve the results of the holistic approach. The main input data was quantitative precipitation estimation, which better assessed the spatial variability of rainfall fields than interpolated ground measurements. The model simulated five episodes. Contrary to expectations, southern headstream area of the basin showed lower coefficient of runoff in comparison with its northern part. Precipitation cores of epizods occurred over the northern part of the basin at the outlet. Outputs from the model were evaluated in relation to measurements carried out in the experimental basin Zbytiny. Key words: Blanice River, HEC-HMS, hydrologic modeling, quantitative precipitation estimation

Alterations along the Mississippi River, such as dams and levees, have greatly reduced the amount of freshwater and sediment that reaches the Louisiana coastal area. Several freshwater and sediment diversions have been proposed to combat the associated land loss problem. To aid in this restoration effort a 1-D numerical model was calibrated, validated, and used to predict the response of the river to certain stimuli, such as proposed diversions, channel closures, channel modifications, and relative sea level rise. This study utilized HEC-RAS 4.0, a 1-D mobile-bed numerical model, which was calibrated using a discharge hydrograph at Tarbert Landing and a stage hydrograph at the Gulf of Mexico, to calculate the hydrodynamics of the river. The model showed that RSLR will decrease the capacity of the Lower Mississippi River to carry bed material. The stage at Carrollton Gage is not significantly impacted by large scale diversions

Since the damming and channelization of the lower Long Tom River in the 1940s and 1950s, the quality and quantity of habitat for coastal cutthroat trout and spring Chinook salmon in the watershed has dramatically diminished. In order to better understand the potential for stream restoration, this study uses 2D hydraulic modeling to determine the impact of reconnecting historical meander bends to the main stem of the lower Long Tom River on localized flooding, sediment erosion and deposition, and salmonid physical habitat. These models compare the current conditions to two restoration scenarios that allow for fish passage given 1, 2, and 5-year flood events at two study sites. This study reveals important variations in the impact of restoration between the study sites and the reconnection methods. It also suggests that there is the potential for a large increase in the area of accessible habitat with stream restoration.

El presente trabajo consiste en el modelamiento hidrológico e hidráulico de la quebrada Cashahuacra ubicada en el distrito de Santa Eulalia con el fin de proponer la estructura de un sistema de alerta temprana que integre estos modelos para evitar la pérdida, primordialmente, de vidas humanas. Se presenta una síntesis de los principales eventos de flujo de detritos ocurridos en dicho lugar así como un marco teórico que aborda conceptos básicos relacionados al estudio de la hidrología e hidráulica. Para el modelo hidrológico, se llevó a cabo la caracterización de la quebrada Cashahuacra y se obtuvo sus parámetros principales, así también, fue necesario la adquisición de los datos históricos de precipitación. De esta manera, el modelo hidrológico fue realizado con el software HEC-HMS versión 4.2 en colaboración con ArcGIS versión 10.2.1. y su extensión HEC-GeoHMS. Así, se pudo determinar los caudales máximos bajo los periodos de retorno de 5, 10, 20, 50, 100, 200 y 500 años. El modelo hidráulico fue desarrollado con el software FLO-2D versión PRO. Tuvo como parámetros de entrada al hidrograma calculado por el modelo hidrológico, a la topografía digital del terreno, y a parámetros reológicos como la viscosidad y el esfuerzo de cedencia. Luego, fueron obtenidas las velocidades y profundidades máximas de los periodos de retorno mencionados líneas arriba. Finalmente, se ha integrado estas dos modelaciones en la estructura de un sistema de alerta temprana frente a huaycos y se ha sugerido la implementación de un radar meteorológico para la quebrada en estudio. / The present work consists of hydrological and hydraulic modeling of the Cashahuacra stream located in the Santa Eulalia district in order to propose the structure of an early warning system that integrates these models to avoid the loss, primarily of human lives. A synthesis of the main debris flow events occurring in that place is presented as well as a theoretical framework that addresses basic concepts related to the study of hydrology and hydraulics. For the hydrological model, the characterization of the Cashahuacra stream was carried out and its main parameters were obtained, as well as the acquisition of the historical precipitation data. In this way, the hydrological model was made with the HEC-HMS software version 4.2 in collaboration with ArcGIS version 10.2.1. and its HEC-GeoHMS extension. Thus, it was possible to determine the maximum flow rates under the return periods of 5, 10, 20, 50, 100, 200 and 500 years. The hydraulic model was developed with the FLO-2D PRO version software. It had as input parameters to the hydrograph calculated by the hydrological model, to the digital topography of the land, and to rheological parameters such as viscosity and yield strength. Then, the maximum speeds and depths of the return periods mentioned above were obtained. Finally, these two models have been integrated into the structure of an early warning system against hurricanes and the implementation of a meteorological radar for the stream under study has been suggested. / Tesis

<p>A big responsibility lies in the hand of local authorities to exercise measures in preventing fatalities and damages during flood occurrences. However, the problem is how flooding can be prevented if nobody knows when and where it will be occurring, and how much water is expected. Therefore, the utilisation of flood models in such studies can be helpful in simulating what is anticipated to occur.</p><p> </p><p>In this study, the HEC-RAS steady flow model was used in calibrating different flood events in Testeboån river, which is situated in the municipality of Gävle in Sweden. The purpose is to provide inundation maps that show the water surface profiles for the various flood events that can help authorities in planning within the area. Moreover, the study would try to address certain issues, which concern one-dimensional models like HEC-RAS in terms of the effects of topographic data and the parameters used for friction coefficient.</p><p> </p><p>Various flood maps were produced to visualise the extents of the floods. In Oppala and Norra Åbyggeby, the big water extents for both the 100-year and the highest probable floods were visible in the forested areas and grasslands, although a few houses were within the predicted flooded areas. In Södra Åbyggeby, Varva, Forsby, and in the northern parts of Strömsbro and Stigslund, the majority of the residential places were not inundated during the 100-year flood calibration, but became flooded during the maximum probable flood. The southern portions of Strömsbro and Stigslund had lesser flood extents and houses were situated within the boundaries of the highest flood. In Näringen, there were also some areas close to the estuary that were flooded for both events.</p><p> </p><p>With the other calibrations performed, two factors that greatly affect the flood extents in the floodplain, particularly in flatter areas were topographic data and the parameters used as friction coefficient.  The use of high resolution topographic data was important in improving the performance of the software. Nevertheless, it must be emphasised that in areas characterised by gentler slopes that bounded the channel and the floodplain, data completeness became significant whereby both ground data and bathymetric points must be present to avoid overestimation of the inundation extent. The water extents also varied with the use of the various Manning’s <em>n</em> for the overbanks, with the bigger value showing greater water extents. Else, in areas with steeper slopes and where the water was confined to the banks, the effect was minimal.</p><p> </p><p>Despite these shortcomings of one-dimensional models, HEC-RAS provided good inundation extents that were comparable to the actual extent of the 1977 flooding.</p><p> </p><p>Modelling real floods has its own difficulties due to the unpredictability of real-life flood behaviours, and more especially, there are time dependent factors that are involved.  Although calibrating a flood event will not exactly determine what is to arise as they might either under- or overestimate such flooding occurrences, still, they give a standpoint of what is more or less to anticipate, and from this,  planning measures can be undertaken.</p>

Floods can result in enormous causalities and huge economic losses in urban and rural regions. In recent years, while assessing the damage, risk analysis and assessment has become an important tool in addressing uncertainty in flood hazards. The lack of knowledge about the water extend, water depth, water velocity and potential damage in case of flood increase the vulnerability of the people to disasters in the flood region. Especially this information is valuable for city planners and decision makers. In case of new settlement area selection, correct decision can be taken by the help of this information. This type of information can be taken from hydraulic models as 1D or 2D. On the other hand, two dimensional (2D) hydraulic modeling becomes a need with increasing trends of very high speed computers and models instead of one dimensional (1D) ones. The ability of solving complex structures within few minutes enhances the use of 2D modeling with the integration of wave motion. In addressing the uncertainty, GIS becomes an important tool in risk assessment by integrating the flood depth, extend and vulnerability issues for definition of the quantitative risk. In this study, 1D and 2D hydraulic modeling is applied and combined with the quantitative vulnerability factors in Dalaman Plain-Turkey. Results show that the area is vulnerable to flood and high monetary damages can be seen in case a flood in the region.

In assuring the energy supply of Turkey, hydroelectric energy plays one of the most important roles in plans formulated to realize equilibrium between energy production and consumption. Hydroelectric power plants on Murat River, a tributary of Euphrates, is a part of the development plan for energy production. Operation of four dams in cascade on Murat River are simulated by using program package HECResSim. For this purpose, ten scenarios are formulated to utilize the hydraulic potential of Murat River between the elevations of 870 m 1225 m. This study provides detailed financial analyses of scenarios and shows how HEC-ResSim program can be used in formulation of alternative scenarios. Electric energy storage requirement due to the rising demand for peaking power is creating a completely new market value, which is also increasing the attractiveness of pumped storage power plants. The results of the simulation performed in Scenario 10 in which two pumped storage power plants are considered have 15% higher internal rate of return value than the other scenarios with conventional turbines. Results demonstrate the increasing attractiveness of the cascade system with reversible pump turbines.

Performance-based measures are used to validate and quantify how likely the system’s results resemble that of the actual data. Its application in inundation studies is performed by comparing the extents of the predicted flood to the real event by measuring their overlap size and getting the percentage of this size to the union of both data. In this study, performances of 1- and 2-dimensional flow models were assessed when used with different topographic data sources, rasterisation cell sizes, mesh resolution and Manning’s values with the help of Geographic Information Systems (GIS). The Generalised Likelihood Uncertainty Estimation (GLUE) was also implemented to evaluate the behaviour and the uncertainties of the Hydrologic Engineering Center-River Analysis System (HEC-RAS) steady-flow model in delineating the inundation extents when various sets of friction coefficients for floodplain and channel were utilised as inputs. Although it was not possible to perform the GLUE procedure with Telemac-2D due to the simulation time, Manning’s n performances’ effects were evaluated using ten randomly selected sets of friction for the channel and floodplain. The LiDAR data, which had the highest resolution, performed well in all simulations, followed by Lantmäteriet data at 50 m resolution. The lowest resolution Digital Terrain Elevation Data (DTED) showed poor resemblance to the actual event and big misrepresentations of flooded areas. Rasterisation cell sizes in HEC-RAS showed minimal effect to the inundation limits when used between 1 m and 5 m, but performance started to deteriorate at 10 m (Lantmäteriet) and 20 m (LiDAR). The 10 m mesh resolution used for LiDAR behaved poorer than the 20 m mesh, which performed well in the different 2D simulations. For HEC-RAS, =0.033 to 0.05 performed well when paired with =0.02 to 0.10. It was apparent, therefore, that the channel’s Manning’s n affected the performances of the floodplain’s . Furthermore, the study also showed that using heterogeneous roughness values corresponding to the different land use classes is not as effective as using single channel and floodplain’s Manning. The dependence of the floodplain’s roughness to the channel’s friction values had also been manifested by Telemac, even though it required lower values than the 1D simulator. = 0.007 to 0.019   and =0.01 to 0.04 gave good performance to the 2D system. In terms of the overall model performance, HEC-RAS 1D exhibited good results for Testeboån. Even when the average distances to the actual data were estimated, the breadths were shorter compared to the most optimal output of the two-dimensional simulator, which showed more overestimated areas, despite the fact that the overlap size with the 1977 actual event was better than HEC-RAS. It could be because the measures-of-fit took into consideration the areal sizes that were over- and under-predicted aside from the overlap sizes between the observed and modelled results. This could be the same reason with the mean distances produced, wherein higher values were computed for Telemac-2D due to its bigger gap from the actual flood as brought by the enlargement in the flood extents. But it was also made known in the study that such ambiguities in the model performance were further contributed by the characteristics of the floodplain’s topography of being flat. Testeboån’s inclination to the banks was averaged at 0.027 m/m, with the central portion at 0.002 m/m. The middle portion of the floodplain was illustrated to contain more uncertain regions, where water extents changed easily as the parameters were altered. Distances greater than 200 m were also mostly located within these inclination values or within 0.005 to 0.006 m/m. The response of distance to the floodplain’s gradient improved when the slope value became higher, and this had been particularly noticed between 0 to 50 m.

A big responsibility lies in the hand of local authorities to exercise measures in preventing fatalities and damages during flood occurrences. However, the problem is how flooding can be prevented if nobody knows when and where it will be occurring, and how much water is expected. Therefore, the utilisation of flood models in such studies can be helpful in simulating what is anticipated to occur.   In this study, the HEC-RAS steady flow model was used in calibrating different flood events in Testeboån river, which is situated in the municipality of Gävle in Sweden. The purpose is to provide inundation maps that show the water surface profiles for the various flood events that can help authorities in planning within the area. Moreover, the study would try to address certain issues, which concern one-dimensional models like HEC-RAS in terms of the effects of topographic data and the parameters used for friction coefficient.   Various flood maps were produced to visualise the extents of the floods. In Oppala and Norra Åbyggeby, the big water extents for both the 100-year and the highest probable floods were visible in the forested areas and grasslands, although a few houses were within the predicted flooded areas. In Södra Åbyggeby, Varva, Forsby, and in the northern parts of Strömsbro and Stigslund, the majority of the residential places were not inundated during the 100-year flood calibration, but became flooded during the maximum probable flood. The southern portions of Strömsbro and Stigslund had lesser flood extents and houses were situated within the boundaries of the highest flood. In Näringen, there were also some areas close to the estuary that were flooded for both events.   With the other calibrations performed, two factors that greatly affect the flood extents in the floodplain, particularly in flatter areas were topographic data and the parameters used as friction coefficient.  The use of high resolution topographic data was important in improving the performance of the software. Nevertheless, it must be emphasised that in areas characterised by gentler slopes that bounded the channel and the floodplain, data completeness became significant whereby both ground data and bathymetric points must be present to avoid overestimation of the inundation extent. The water extents also varied with the use of the various Manning’s n for the overbanks, with the bigger value showing greater water extents. Else, in areas with steeper slopes and where the water was confined to the banks, the effect was minimal.   Despite these shortcomings of one-dimensional models, HEC-RAS provided good inundation extents that were comparable to the actual extent of the 1977 flooding.   Modelling real floods has its own difficulties due to the unpredictability of real-life flood behaviours, and more especially, there are time dependent factors that are involved.  Although calibrating a flood event will not exactly determine what is to arise as they might either under- or overestimate such flooding occurrences, still, they give a standpoint of what is more or less to anticipate, and from this,  planning measures can be undertaken.

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