Simulation Of Flood Events Research Articles

MAP D-PHASE: Real-Time Demonstration of Weather Forecast Quality in the Alpine Region

Demonstration of probabilistic hydrological and atmospheric simulation of flood events in the Alpine region (D-PHASE) is made by the Forecast Demonstration Project in connection with the Mesoscale Alpine Programme (MAP). Its focus lies in the end-to-end flood forecasting in a mountainous region such as the Alps and surrounding lower ranges. Its scope ranges from radar observations and atmospheric and hydrological modeling to the decision making by the civil protection agents. More than 30 atmospheric high-resolution deterministic and probabilistic models coupled to some seven hydrological models in various combinations provided real-time online information. This information was available for many different catchments across the Alps over a demonstration period of 6 months in summer/fall 2007. The Web-based exchange platform additionally contained nowcasting information from various operational services and feedback channels for the forecasters and end users. D-PHASE applications include objective model verification and intercomparison, the assessment of (subjective) end user feedback, and evaluation of the overall gain from the coupling of the various components in the end-to-end forecasting system.

Hydrometeorological ensemble simulations of flood events over a small basin of Majorca Island, Spain

AbstractA hydrometeorological modelling study is designed in order to assess the feasibility of high‐resolution mesoscale‐model‐driven runoff simulations for a small basin of Majorca in the Balearic Islands. Four intense precipitation events, which caused flood events of different magnitudes over the Albufera basin (with a drainage area of 610 km2), are analysed. The Hydrologic Engineering Center's Hydrologic Modeling System (HEC‐HMS) runoff model is used to generate the hydrological simulations. The lack of flow measurements in the basin poses great difficulties in the evaluation of the rain‐gauge‐driven runoff simulations. Therefore the runoff model is run under the assumption that a best estimation of the hydrological model parameters, mainly related to the infiltration properties of the watershed, can be obtained from the high‐resolution observational campaign developed by the Coordination of Information on the Environment (CORINE) Land Cover project. The non‐hydrostatic fifth‐generation Pennsylvania State University / NCAR Mesoscale Numerical Model (MM5) is used to provide quantitative precipitation forecasts for the events. The MM5‐driven runoff simulations are compared against stream‐flow simulations driven by the rainfall observations, thus employing the hydrological model as a validation tool. In addition to the control MM5 simulations, a multi‐physics ensemble is carried out: various combinations of the physical parametrizations of the MM5 model (cloud microphysics, moist convection and boundary‐layer schemes) are adopted, in order to better encompass the atmospheric processes leading to the high precipitation amounts. Results show that high‐resolution numerical weather experiments in this area of complex orography accurately reproduce most of the extreme precipitation events under study, enabling potentially valuable discharge simulations, despite the small size of the basin. The value of the multi‐physical model ensemble in conveying the uncertainty of precipitation, and therefore the discharge experiments, is also discussed. Copyright © 2008 Royal Meteorological Society

MAP D‐PHASE: real‐time demonstration of hydrological ensemble prediction systems

AbstractMesoscale Alpine Programme Demonstration of Probabilistic Hydrological and Atmospheric Simulation of Flood Events (MAP D‐PHASE) is a forecast demonstration project aiming at demonstrating recent improvements in the operational use of end‐to‐end forecasting system consisting of atmospheric models, hydrological prediction systems, nowcasting tools and warnings for end‐users. Both deterministic and ensemble prediction systems (EPSs) have been implemented for the European Alps (atmospheric models) and a selection of mesoscale river basins (hydrological models) in Central Europe. A first insight into MAP D‐PHASE with focus on operational ensemble hydrological simulations is presented here. Copyright © 2008 Royal Meteorological Society

Desorption of Dieldrin from field aged sediments: Simulating flood events

Background, Aim and Scope With the predicted climate change, it is expected that the chances of flooding may increase. During flood events, sediments will resuspend and when the sediments are polluted, contaminants can be transferred to the surrounding water. Mass transfer of organic compounds like Persistent Organic Pollutants (POPs) from soils and sediments to the surrounding aqueous phase are essential regarding fate and transport of these chemicals in the aqueous environment. The distribution of POPs between sorbed and aqueous phases and the time needed to obtain equilibrium are required to calculate the exposure to potential receptors. A reactor was designed in which the water flow is controlled and low POP concentrations could be measured by tenax extraction outside the reactor vessel. This reactor design named SPEED (Solid Phase Extraction with External Desorption) was used to study desorption from aged contaminated sediment in relation to sediment particle size.

실시간 저수지 탁수 감시 및 관리를 위한 의사결정지원시스템 개발 및 검증: 대청댐 사례

Reservoir turbidity flows degrade the efficiency and sustainability of water supply system in many countries located in monsoon climate region. A decision support system called RTMMS aimed to assist reservoir operations was developed for the real time monitoring, modeling, and management of turbidity flows induced by flood runoffs in Daecheong reservoir. RTMMS consists of a real time data acquisition module that collects and stores field monitoring data, a data assimilation module that assists pre-processing of model input data, a two dimensional numerical model for the simulation of reservoir hydrodynamics and turbidity, and a post-processor that aids the analysis of simulation results and alternative management scenarios. RTMMS was calibrated using field data obtained during the flood season of 2004, and applied to real-time simulations of flood events occurred on July of 2006 for assessing its predictive capability. The system showed fairly satisfactory performance in reproducing the density flow regimes and fate of turbidity plumes in the reservoir with efficient computation time that is a vital requirement for a real time application. The configurations of RTMMS suggested in this study can be adopted in many reservoirs that have similar turbidity issues for better management of water supply utilities and downstream aquatic ecosystem.

Coupled surface and ground water models for investigating hydrological processes

AbstractThis study examines a physical based distributed‐parameter model combining surface runoff and ground water flow. Surface runoff is composed of both overland flow and river flow components, and the ground water module considers the unsaturated zone and saturated zone in an unconfined aquifer system. Previous works of surface flow module development was presented, the ground water module development and complete hydrologic processes simulations are conducted in this paper. Proposed watershed model is designed to deal with physics‐based multiple processes occurring in watershed, including evaporation, infiltration, percolation, surface runoff and ground water flow. This study used a proposed watershed model for the simulations of extreme flood events and long‐term periods that occurred in the Shihmen reservoir watershed from 1986 to 2001. This hydrological model is a flash reacting watershed model, showing good potential for storm based simulations, recession period description and long‐term modelling. Therefore, the proposed model is confirmed to be suitable for Shihmen reservoir watershed simulations. Copyright © 2007 John Wiley & Sons, Ltd.

Distributed Flood Simulations with Coupling Gauge Observations and Radar-rainfall Estimates

This study used a two-dimensional diffusion hydrodynamic model for the simulation of extreme flood events that occurred in the Shihmen reservoir watershed from 1989 to 2001. The alternating direction explicit scheme (ADE) with various horizontal spacings from 120 to 240 m at an incremental interval of 40 m was conducted for flood simulations. Spatial precipitation was provided by the gauge interpolations and weather radar rainfall estimate schemes. A case study, Typhoon Nari on September 16–18, 2001, was then performed using radar-derived rainfall with coupling two-dimensional diffusion hydrodynamic model in flood routing investigations. Numerical results revealed acceptable agreement between the observed and simulated reservoir stage hydrographs. Results of 120 and 160 m spacing had similar values on error indicators while the 160 m grids can greatly reduce computational time by 40% than that of 120 m grids. Precipitation is identified to be the main factor forcing model result.

Comparison of different approaches to quantify the reliability of hydrological simulations

Abstract. The focus of this study was to compare different uncertainty estimation approaches to evaluate their ability to predict the total amount of uncertainty in hydrological model predictions. Three different approaches have been compared. Two of them were based on Monte-Carlo sampling and the third approach was based on fitting a probability model to the error series of an optimized simulation. These approaches have been applied to a lumped and a semi-distributed model variant, to investigate the effects of changes in the model structure on the uncertainty assessment. The probability model was not able to predict the total amount of uncertainty when compared with the Monte-Carlo based approaches. The uncertainty related to the simulation of flood events was systematically underestimated.

Simulating flood events in mesoscale watershed:a case study from River Xitiaoxi Watershed in the upper region of Taihu Basin

以太湖上游西苕溪流域为研究对象，通过分布式水文模型HEC-HMS模拟次降雨洪水过程:采用可视化数据存储系统HEC-DSS建立水义气象数据库，利用Geodatabase地理数据库技术集成流域自然属性数据库，通过距离平方倒数法对雨量数据进行空间插值，SCS曲线数法计算水文损失，运动波法计算直接径流与河道洪水演进，选用基流指数退水法模拟流域基流，并对模型中水库模拟部分进行适当修正．经模型校验，模拟结果表明，计算流量与观测流量拟合较好，效率系数大于0．8．洪峰流量误差低于4%，峰现时间误差低于2 h，该模型在土地利用变化对洪水水文要素的影响研究方面有较好的应用前景．;Flood events in River Xitiaoxi Watershed in the upper region of Taihu Basin were simulated by distributed hydrologic modeling system HEC-HMS. The database of hydrology and meteorology in studied region was set up by visual storage system HEC-DSS. The database of the natural attributes of basin was integrated by the technique of GIS Geo-database. The total storm mean area precipitation was calculated by inverse-distance-squared method. SCS Curve Number Loss Model was selected to compute runoff volumes. Kinematic-wave Model was used to model direct runoff and channel flow. Base flow was modeled by Exponential Recession Model and the reservoir model was improved. After calibration and validation, the simulated flow and observed flow fit so good that the efficiency coefficient was more than 0. 8, with error of peak flow within 4% , and error of peak flow time within 2 hours, which illustrated that HEC-HMS may be applicable area in simulating the impacts of land use change on hydrological regimes such as floods.

A validated fast algorithm for simulation of flooding events in plains

AbstractHydrological modelling in large plains is not a straightforward task owing to the crucial influence of several elements, namely, accumulation of water on local depressions, absence of an integrated drainage network, generalized meagre surface slopes, strong sensitivity of the soil water content before rainfall events, and variation of the soil infiltration capacity with numerous transient and local factors. It would then appear that distributed hydrological models (DHM) are prone to produce better results than lumped‐parameter models. The trade‐off in setting up a DHM, however, is how realistic its results are as compared to its simplicity.This paper presents a physically based DHM, named AQUA, which can handle large domains discretized in squared cells of typically 80 m a side. In order to address properly the flow resistance, it relies on a relaxation parameter (α) with different values for the watercourses and the terrain. Likewise, an infiltration function (I) regulates the downward movement of water. Moreover, the model is supported by an adequate description of the gentle topographical features, which was achieved by a digital elevation model (DEM) from radar interferometry.The testing phase took into account the Santa Catalina Creek Basin (158 km2, centre Buenos Aires Province in Argentina). The results were quite encouraging, as the model was able to reproduce the effect of various rainfall scenarios. Sensitivity analyses of the model parameters were consistent with the actual simulation results. AQUA was tested against the well‐known HEC‐1 model, with a fairly good match of their results. Copyright © 2006 John Wiley & Sons, Ltd.

FLUMEN 모형을 이용한 홍수범람모의

본 연구에서는 천수방정식을 지배방정식으로 하고, 유한체적법에 기반을 둔 FLUMEN 수치모형을 이용하여 홍수범람모의를 수행하였다. 실제 지형에서의 홍수범람모의 적용에 앞서 단순화된 문제들에 모형을 적용시켜 적용 타당성을 검증하였다. 수치계산 결과는 다른 기법을 통한 결과 및 수리모형실험 관측결과와 양호하게 일치하였다. 적용타당성의 검증 후, 실제 지형에서의 홍수범람을 모의하였다. 본 모형을 사용한 실제 지형에서의 홍수범람모의 결과는 향후 홍수범람지도 제작에 기초적인 자료를 제공할 것으로 사료된다. In this study, flood inundations have been simulated by using the numerical model FLUMEN solving the shallow-water equations with a finite volume method. Before applying to a real problem, the numerical model is first applied to simplified problems. Obtained numerical results are verified by comparing with available analytical solutions and laboratory measurements. Reasonable agreements are observed. The model is then applied to a simulation of flood events with real geometries. The results of this study will provide basic information to make a flood inundation map.

DEVELOPMENT OF A FLOOD SIMULATOR FOR A FLOOD RISK COMMUNICATION TOOL

In this paper, we present a new type flood simulator for flood risk communication. The characteristics of presented simulator are:(1) Calculation speed of flood flow is very fast;(2) It offers a fully interactive user interface;(3) It provides the property damage assessment based on the simulated results;(4) It visualizes the simulated results with three-dimensional cityscapes. The shallow water equations are solved by using a combination of leapfrog scheme and staggered grid to accelerate the flood flow calculation. Meanwhile we develop an execution sequences controlling function that enable parallel processing the visualization of current state of simulated flow as well as the simulation, and it underlies the interactive user interface. Moreover in order to implement these characteristics, we apply four-dimensional Geographic Information System (4D-GIS), which is suitable to manage and to simulate flood events with 3D geographic data and the simulated time sequence. Through an experiment, presented simulator shows a very promising performance, which would significantly improve the flood damage understanding of society.

Comparison of infiltration models to simulate flood events at the field scale

Most runoff simulation and infiltration models have been developed at the global-catchment scale or the local-soil column scale. Few models have been specifically developed at the scale of agricultural fields and there are no guidelines to help modellers choose an adequate model to simulate overland flow and hence analyse the impact of different soil management practices on flood generation. A comparison is undertaken to select and calibrate models that simulate Hortonian overland flow at the field or small plot scale. The proposed methodology couples a runoff production model to a unit hydrograph transfer function. Four different models were tested: Philip, Morel-Seytoux, Horton and SCS. These models differ by their mathematical structure and the parameters to be calibrated while input hydrologic data are the same site data: rainfall/runoff and initial water content. The models are calibrated on 14 events and validated on 14 others. The results of both the calibration and validation phases are compared on the basis of their performance with regards to six objective criteria, three global criteria and three relative criteria representing volume, peakflow, and the root mean square error. The first type of criteria gives more weight to strong events whereas the second considers all events to be of equal weight. The results show that the calibrated parameter values are dependent on the type of objective criteria used. Furthermore, when analysing the performance of the six objective criteria used, it can be seen that the global volume, global RMSE and relative peakflow criteria give the best compromise between bias and precision. Within the selected modelling framework, Morel-Seytoux's model performed better than the other three and the SCS gave the worst results. Horton's model showed to be more consistent in overall performance than Philip's model. Results also highlight problems related to the simulation of low flow events and intermittent rainfall events.

Flood hydrograph attenuation induced by a reservoir system: analysis with a distributed rainfall‐runoff model

AbstractSpatially distributed hydrologic models can be effectively utilized for flood event simulation over basins where a complex system of reservoirs affecting the natural flow regime is present. Flood peak attenuation through mountain reservoirs can, in fact, mitigate the impact of major floods in flood‐prone areas of the lower river valley. Assessment of this effect for a complex reservoir system is performed with a spatially distributed hydrologic model where the surface runoff formation and the hydraulic routing through each reservoir and the river system are performed at a fine spatial and time resolution.The Toce River basin is presented as a case study, because of the presence of 14 active hydroelectric dams that affect the natural flow regime. A recent extreme flood event is simulated using a multi‐realization kriging method for modelling the spatial distribution of rainfall. A sensitivity analysis of the key elements of the distributed hydrologic model is also performed. The flood hydrograph attenuation is assessed. Several possible reservoir storage conditions are used to characterize the initial condition of each reservoir. The results demonstrate how a distributed hydrologic model can contribute to defining strategies for reservoir management in flood mitigation. Copyright © 2004 John Wiley & Sons, Ltd.

Sequential Assimilation ofERS-1SAR Data into a Coupled Land Surface–Hydrological Model Using an Extended Kalman Filter

Abstract A first attempt to sequentially assimilate European Space Agency (ESA) Remote Sensing Satellite (ERS) synthetic aperture radar (SAR) estimations of surface soil moisture in the production scheme of a lumped rainfall–runoff model has been conducted. The methodology developed is based on the use of an extended Kalman filter to assimilate the SAR retrievals in a land surface scheme (a two-layer hydrological model). This study was performed in the Orgeval agricultural river basin (104 km2), a subcatchment of the Marne River, 70 km east of Paris, France. Assimilation was tested over a 2-yr period (1996 and 1997), corresponding to 25 SAR measurements. The improvements observed in simulating flood events demonstrate the potential of sequential assimilation techniques for monitoring surface functioning models with remote sensing data. It was demonstrated that the method could correct for some errors or uncertainties in the input data (precipitation and evapotranspiration), provided that these errors are ...

The exponential store: a correct formulation for rainfall—runoff modelling

Stores are widely used tools in conceptual, soil-moisture accounting rainfall—runoff models. Various mathematical laws are used to describe the outflow of such stores. The exponential store has received less attention than the linear store, but it has proved to be a highly efficient tool in streamflow modelling. The aim of this study is to show that the common way of dealing with this store'without integration in time'is mathematically and physically flawed. This misuse can result in poorer reliability and efficiency of rainfall—runoff models that include such a store. Surprisingly, this inconsistency had a significant impact on only a limited number of catchments among the 138 used to carry out the tests. However, it can have dramatic consequences for the simulation of large flood events. Therefore, an exact discrete formulation should be preferred in rainfall—runoff models.

Coupled rainfall model and discharge model for flood frequency estimation

A method was designed to study frequency distributions of hydrologic variables (rainfall and discharge) which combined a stochastic model for hourly rainfall with a general conceptual model for transforming rainfall into discharge. The model generates many different flood events over a given simulation period to evaluate hydrologic risks. The Simulated Hydrographs for flood Probability Estimation (SHYPRE) method was based on the use of observations to describe phenomena and statistically reproduce them. Frequency distributions of hydrological variables are built empirically from simulated rainfall and flood events. Extrapolation of these frequency distributions toward rare frequencies is performed by generating very different events over a long simulation period rather than by directly fitting a theoretical probability distribution on observed values. This method yields an original estimation of flood quantiles from common to rare frequencies and provides complete temporal data about these floods. In addition, the approach supplies more stable estimates of flood quantiles than statistical distributions fitted on observed values, even for frequent events. This is due to a better integration of rainfall data and the parametric design stability of the two models (rainfall model and rainfall‐discharge model).

Design Flood Estimation Using GIS Supported GIUHApproach

Quantitative understanding and prediction of theprocesses of runoff generation and its transmission to theoutlet represent one of the most basic and challenging areasof hydrology. Traditional techniques for design floodestimation use historical rainfall-runoff data for unithydrograph derivation. Such techniques have been widelyapplied for the estimation of design flood hydrograph at thesites of gauged catchment. For ungauged catchments, unithydrograph may be derived using either regional unithydrograph approach or alternatively GeomorhologicalInstantaneous Unit Hydrograph (GIUH) approach. The unithydrograph thus derived may be used for the simulation offlood events for the ungauged catchments. In this study Gambhiri dam catchment located inRajasthan, India is selected for applying this approach. Gambhiri river is a small tributary of the Berach/Banasriver of the Chambal basin in Rajasthan, India. Theobjective of the present study is to apply GeographicalInformation System (GIS) supported GIUH approach for theestimation of design flood. A mathematical model has beendeveloped at the National Institute of Hydrology, whichenables the evaluation of the Clark Model parameters usinggeomorphological characteristics of the basin. This modelhas been applied for the present study.From this study it is observed that the peakcharacteristics of the design flood are more sensitive tothe various storm pattern as well as method of criticalsequencing followed for the computation of design stormpatterns. Earlier estimates for the peak and time to peakhydrograph was 9143.74 cumec and 18 hrs. respectively.However, the estimates for the peak characteristics ofdesign flood hydrograph obtained from the GIUH basedapproach are 11870.6 cumec and 19 hrs. respectivelyconsidering the same design storm pattern.

Testing AGNPS for soil erosion and water quality mode11ing in agricultural catchments in Hesse (Germany)

Until recently, no suitable computer model was available to quantify P and N yields of nonpoint sources into surface water in Central German watersheds. The event-based erosion; and nutrient transport model AGNPS (Version 3.65), developed in the USA, was adapted to Central German landscape conditions and linked to a GIS. Drawing on a two-year program of water quality measurements and on hydrologic data collected over 33 years, this modified model was tested in two medium-sized agricultural watersheds in the state of Hesse (Germany). With deviations of 1.796 and 3.896, runoff volumes for all observed and simulated flood events showed a high level of agreement in both watersheds. Only for one of the two watersheds were sediment and total phosphorus yield computed satisfactorily, with average errors of 596 (sediment) and 696 (total P). However, the model correctly registered the overall dynamics of the system as well as the differences of sediment and total P yield between the two watersheds. The modified AGNPS model can thus be employed by environmental agencies as a useful planning tool.

Modification of AGNPS for Agricultural Land and Climate Conditions in Central Germany

AbstractUntil recently, no suitable computer model was available to quantify P and N yields of nonpoint sources into surface water in central German watersheds. The event‐based erosion and nutrient transport model AGNPS (Version 3.65), developed in the USA, was adapted to central German landscape conditions and linked to a GIS. Drawing on a 2‐yr program of water quality measurements and on hydrologic data collected during 33 yr, this modified model was tested in two medium‐sized agricultural watersheds in the state of Hesse, Germany. With deviations of 1.7 and 3.8%, runoff volumes for all observed and simulated flood events showed a high level of agreement in both watersheds. Peak flows showed larger errors averaging 14.8 and 24%. Only for one of the two watersheds were sediment and total P yield computed satisfactorily, with average errors of 5% (sediment) and 6% (total P). Deviations for the second watershed were considerably greater. The same is true for the dissolved P and N yields. In the case of small events, AGNPS consistently overestimated the particulate P yield in both watersheds. However, the model correctly registered the overall dynamics of the system as well as the differences of sediment and total P yield between the two watersheds. The modified AGNPS model can thus be employed by environmental agencies as a useful planning tool.