Detailed Flood Research Articles

홍수범람지도 작성을 위한 GIS기반 1차원 동역학적 해석 기법

홍수는 한 국가의 발전에 영향을 미칠 수 있는 주요 자연재해 중 하나이다. 세계 각국에서는 댐, 저류지, 제방 등과 같은 수공 구조물의 설계빈도를 초과하는 이상 홍수가 발생할 경우에 대비하여 비구조적 대책의 일환으로 홍수범람지도를 작성하고 있다. 본 연구는 댐 붕괴에 대한 1차원 하천수리해석 모형(DAMBRK)과 GIS를 연계한 홍수범람지도 작성 방법에 관해 보여준다. 이를 위해 여러 가지의 댐 붕괴 시나리오에 따라 붕괴유출량을 산정하고, 이 중 가장 극한조건에 대한 하류부 홍수추적을 통해 하류부 주요지점별 첨두유량, 최고홍수위, 홍수파 도달시간, 최고홍수위 도달시간을 산정하고 최고홍수위와 좌 우 제방고도 비교한다. 그리고 이러한 하천수리해석 결과를 GIS를 연계하여 수심별 홍수범람지도를 작성하는 방법에 관해 상세하게 보여준다. 본 연구에서 제안한 홍수범람지도 작성방법은 홍수터 해석에 대해 1차원 하천수리해석 모형이 가지는 한계점을 보완할 수 있다. Flooding as one of the major natural disasters affects country's economy. Most country is establishing a flood inundation maps as a non-structural measures to prevent damages from an abnormal flooding over the design criteria of hydraulic structures such as dams, storages, and levees et al. This study suggests method to establish GIS based inundation map induced by dam-break flood simulated by 1D hydrodynamic model(DAMBRK). In this study, the dam-break hydrograph were simulated by various scenario events and especially for the extreme event, peak discharge, peak water surface elevation, arrival time of flood wave and peak water surface elevation are calculated by flood routing at the control points and peak water surface elevation was compared with levee height to detect inundation. In addition, the detailed flood inundation mapping processes at each water level linking with GIS are presented in this study. The proposed method to establish a flood inundation map is able to complement the limitation of 1D hydrodynamic model in analyses of flood plains.

A probabilistic model for real‐time flood warning based on deterministic flood inundation mapping

AbstractDeterministic flood inundation mapping is valuable for the investigation of detailed flood depth and extent. However, when these data are used for real‐time flood warning, uncertainty arises while encountering the difficulties of timely response, message interpretation and performance evaluation that makes statistical analysis necessary. By incorporating deterministic flood inundation map outputs statistically by means of logistic regression, this paper presents a probabilistic real‐time flood warning model determining region‐based flood probability directly from rainfall, being efficient in computation, clear in message, and valid in physical meaning. The calibration and validation of the probabilistic model show a satisfactory overall correctness rate, with the hit rate far surpassing the false alarm rate in issuing flood warning for historical events. Further analyses show that the probabilistic model is effective in evaluating the level of uncertainty lying within flood warning which can be reduced by several techniques proposed in order to improve warning performance. Copyright © 2011 John Wiley & Sons, Ltd.

Trends in flood seasonality of the River Ouse (Northern England) from archive and instrumental sources since AD 1600

The last decade has witnessed an increase in the application of historical records (historical and documentary) in developing a more complete understanding of high-magnitude flood frequency; but little consideration has been given to the additional information that documentary accounts contain, particularly relating to flood seasonality. This paper examines the methods and approaches available in long-term flood seasonality analysis and applies them to the River Ouse (Yorkshire) in Northern England since AD 1600. A detailed historical flood record is available for the City of York consisting of annual maxima flood levels since AD 1877, with documentary accounts prior to this. A detailed analysis of long-term flood seasonality requires confidence in the accuracy and completeness of flood records; as a result the augmented flood series are analysed using three strategies: firstly, considering all recorded floods since AD 1600; secondly, through detailed analysis of the more complete record since AD 1800; and finally, applying a threshold to focus on high-magnitude flood events since AD 1800. The results identify later winter flooding, particularly in the second half of the twentieth century, with a notable reduction in summer flood events at York during the twentieth century compared to previous centuries. Flood generating mechanisms vary little between the periods considered, with a general pattern of stability in the ratio of floods incorporating a snowmelt component.

Resilience, vulnerability and adaptive capacity of an inland rural town prone to flooding: a climate change adaptation case study of Charleville, Queensland, Australia

Australia is currently experiencing climate change effects in the form of higher temperatures and more frequent extreme events, such as floods. Floods are its costliest form of natural disaster accounting for losses estimated at over $300 million per annum. This article presents an historical case study of climate adaptation of an Australian town that is subject to frequent flooding. Charleville is a small, inland rural town in Queensland situated on an extensive flood plain, with no significant elevated areas available for relocation. The study aimed to gain an understanding of the vulnerability, resilience and adaptive capacity of this community by studying the 2008 flood event. Structured questionnaires were administered in personal interviews in February 2010 to householders and businesses affected by the 2008 flood, and to institutional personnel servicing the region (n = 91). Data were analysed using appropriate quantitative and qualitative techniques. Charleville was found to be staunchly resilient, with high levels of organisation and cooperation, and well-developed and functioning social and institutional networks. The community is committed to remaining in the town despite the prospect of continued future flooding. Its main vulnerabilities included low levels of insurance cover (32% residents, 43% businesses had cover) and limited monitoring data to warn of impending flooding. Detailed flood modelling and additional river height gauging stations are needed to enable more targeted evacuations. Further mitigation works (e.g., investigate desilting Bradley’s Gully and carry out an engineering assessment) and more affordable insurance products are needed. Regular information on how residents can prepare for floods and the roles different organisations play are suggested. A key finding was that residents believe they have a personal responsibility for preparation and personal mitigation activities, and these activities contribute substantially to Charleville’s ability to respond to and cope with flood events. More research into the psychological impacts of floods is recommended. Charleville is a valuable representation of climate change adaptation and how communities facing natural disasters should organise and operate.

Assessing the retention capacity of a floodplain using a 2D numerical model

Assessing the retention capacity of a floodplain using a 2D numerical modelThis paper presents a method for assessing the retention capacity of a floodplain in the course of flooding and for estimating the significance of its water storage for transforming a flood wave. The method is based on two-dimensional numerical modeling of the flood flow in a river channel and in the adjacent floodplains, and is suitable for cases when the morphology of the flooding area is variable and complex, e.g. broad inundation areas with meandering channels. The approach adopted here enables us to quantify the retention capacity for inundation areas of various characters and with various land uses, and provides a tool for estimating the efficiency of possible measures for increasing the water storage capacity of a floodplain. The retention capacity is estimated using an evaluation of a series of detailed flood flow modeling results; the flood wave transformation effect is predicted with the aim of creating a non-linear reservoir model. A parametric study of the floodplain retention capacity for the upper branch of the Lužnice River is presented here, and the results for the current state and for various hypothetical scenarios of changes in geometry and land use are evaluated and compared.

ParBreZo: A parallel, unstructured grid, Godunov-type, shallow-water code for high-resolution flood inundation modeling at the regional scale

Topographic data are increasingly available at high resolutions (<10 m) over large spatial extents to support detailed flood inundation modeling and loss estimation analyses required for flood risk management. This paper describes ParBreZo, the parallel implementation of a two-dimensional, Godunov-type, shallow-water code, to address the computational demand of high-resolution flood modeling at the regional scale (10 2–10 4 km 2). A systematic approach to unstructured grid partitioning (domain decomposition) is presented, and the Single Process Multiple Data (SPMD) paradigm of distributed-memory parallelism is implemented so the code can be executed on computer clusters with distributed memory, shared memory, or some combination of the two (now common with multi-core architectures). In a fully-wetted, load-balanced test problem, the code scales very well with a parallel efficiency of close to 100% on up to 512 processes (maximum tested). A weighted grid partitioning is used to partially address the load balancing challenge posed by partially wetted domains germane to flooding applications, where the flood extent varies over time, while the partitioning remains static. An urban dam-break flood test problem shows that weighted partitions achieve a parallel efficiency exceeding 70% using up to 48 processes. This corresponds to a 97% reduction in execution time so results are obtained in a matter of minutes, which is attractive for routine engineering analyses. A hurricane storm surge test problem shows that a 10 m resolution, 12 h inundation forecast for a 40 km length of coastline can be completed in under 2 h using 512 processors. Hence, if coupled to a hurricane forecast system capable of resolving storm surge, inundation forecasts could be made at 10 m resolution with at least a 10 h lead time.

Uncertainties in flood risk mapping: a case study on estimating building damages for a river flood in Finland

AbstractIn our review of recent flood risk mapping approaches in Europe, we noted that the sources of uncertainty were rarely questioned. We demonstrated potential sources of uncertainty in flood risk mapping of buildings using a case study of a spring flood in 2005, in Kittilä, Finland. One‐ and two‐dimensional hydraulic models of the flood corresponded well with the actual inundation. The initial modelling result of the inundated buildings differed considerably from reality, but this could be improved through modelling performed with more diverse building elevation data. The accuracy of the digital terrain model is a key determinant in the accuracy of flood hazard modelling. An exposure analysis of buildings is often utilized by an overlay analysis of map layers representing both the flood and the buildings. However, we indicated that the analysis may be partly hindered by the characteristics and inaccuracies of the building datasets used and the modelled flood. In flood damage modelling, the average damages calculated from the database were used, as empirical damage data were too general for a detailed flood damage assessment. Damage modelling with empirical and synthetic damage data could be made more reliable through better archiving of actual flood damages and by performing more diverse damage estimates of standard buildings.

Marchlyn Mawr additional stored energy project

Marchlyn Mawr is located in North Wales and serves as the upper storage reservoir for the Dinorwig Power Station, which operates a 1728 MW pumped storage scheme. Owing to increasing demands on the existing power generation capabilities within the UK, MWH was commissioned by First Hydro Company to provide a detailed engineering solution that would enable the reservoir level to be raised and provide an additional 1·1 GWh of stored energy within the hydro-electric system. The initial scope of work provided by the Client required raising the reservoir level by 2·5 m. However, detailed flood studies carried out during the feasibility stage demonstrated that by raising the crest by 2·5 m and enlarging the overflow could enable a 3·3 m increase in the operating top water level, thereby increasing the available head for power generation. An insight into the measures taken to satisfy the environmental conditions imposed by the planning application is given, as well as the results of full-scale preconstruction trials that were carried out on site, which resulted in modifications to the final design and construction sequence. The engineering solution involved the construction of a 620 m long retaining wall, raising of the dam crest level using rockfill derived from slate waste, enlargement of the existing overflow structure as well as modifications to appurtenant structures and the extension of the original grout curtain.

A refined chronology of catastrophic outflow events in Ares Vallis, Mars

We investigate the geomorphology and chronology of catastrophic flooding in a major martian outflow channel, Ares Vallis. We use recently acquired stereo and colour images and derived topographic data with grid-spacing of 50 m from the High Resolution Stereo Camera (HRSC) onboard Mars Express to constrain the detailed flood geomorphology of proximal Ares Vallis. We identify morphologic evidence for 6 distinct erosion surfaces that were likely formed by multiple episodes of catastrophic flooding. These surfaces occur at distinct topographic levels, exhibit multiple sets of flood grooves, and contain distinct post-flood crater populations. Crater count statistics on the flood-eroded surfaces from MRO Context Camera (CTX) and Thermal Emission Imaging System (THEMIS) visible images indicate that flooding was initiated during the Late Noachian/Early Hesperian at ∼ 3.6 Ga. The morphology data confirm that the oldest flooding events occurred on the topographically highest erosion surfaces while subsequent floods abandoned the upper surfaces and continued to modify craters in the topographically lowest, main channel of Ares Vallis into the Late Hesperian/Early Amazonian (∼ 2.5 Ga). Our results suggest that release of water to Ares Vallis likely occurred at repeated intervals over a long period of geological time, thus supporting recent numerical modelling studies that suggest a recharging water source.

Continuous simulation for flood estimation in ungauged mesoscale catchments of Switzerland – Part I: Modelling framework and calibration results

Summary With the aim of calibrating a large number of catchments for a semi-distributed, process-based conceptual hydrological model, we introduce a straightforward yet robust automatic calibration procedure. Since identification of a global parameter optimum is not feasible in practical terms, the procedure presents a trade-off between computational time and algorithm complexity to identify, with reasonable effort, a parameter set that is well representative of the catchment’s dynamics. In its standard mode, the calibration combines three efficiency scores which are evaluated both for the entire calibration period and in terms of their annual and monthly variations. These scores are furthermore assessed only in their relevant value range, producing a comprehensive overall acceptability score which is used to guide an iterative parameter search algorithm. An additional set of four flood-sensitive scores is added, thereby improving results in the peak-flow range. Calibration was done for 140 mesoscale (roughly 10–1000 km2) catchments in Switzerland, using the hydrological modelling system PREVAH (Precipitation–Runoff-EVApotranspiration-HRU related model) in hourly time steps. For 49 representative catchments with long gauge records, a median Nash–Sutcliffe efficiency (NSE) of 0.75 was achieved for the calibration period in standard mode. The limited loss in efficiency when moving to the validation period (median NSE: 0.72) proves the stability and representativity of the parameter sets identified, while a Monte-Carlo analysis underscores the effectiveness of our procedure. The Nash–Sutcliffe efficiencies for the additional flood calibration are slightly lower, but again almost equally high for the calibration (0.69) and the validation (0.67) period. Despite the concessions made to improve peak-flow results, the simulation’s hydrological plausibility was not compromised. The ultimate goal of our study is flood estimation in ungauged Swiss catchments through continuous simulation using PREVAH. With the extensive calibration task presented in this article, the foundation is laid for regionalisation of the tuneable model parameters, which will be addressed in the companion paper ( Viviroli et al., 2009a ), along with detailed flood estimation results.

Site modelling methods for detecting hydrologic alteration of flood frequency and flood duration in the floodplain below the carlyle dam, lower Kaskaskia River, Illinois, USA

AbstractReports concerning the influence of dams on river hydrology vary among researchers, interest groups and government agencies. These often contradicting statements may occur because changes in hydrology caused by dams are distinct for each dam and river watershed. The objective of this research was to use site specific techniques to determine if the 1967 installation of the Carlyle Dam, lower Kaskaskia River, Illinois, altered flood frequency and duration within the forested floodplain located below the dam. Results indicated a decrease in flood duration and frequency, and a decrease in annual flood frequency variation at a site 6.4 km below the dam. Pre‐dam versus post‐dam differences in flood frequency and duration at the site 32.2 km below the dam were related to climate rather than dam effects. Although dam impacts are a concern, this research shows that distance downstream from the dam and downstream tributary and watershed characteristics should be considered before assuming that the dam has changed hydrologic parameters for portions of rivers. This research also indicates that areas of the lower Kaskaskia River may still maintain hydrologic ecological integrity, and could be targeted for restoration and adaptive management purposes. Hydrologic modelling combined with river gage and on‐site well measurement techniques presented in this study could provide detailed flood frequency and duration information for land use, sociological and geomorphological questions in focus areas within river floodplains. Copyright © 2008 John Wiley &amp; Sons, Ltd.

Analysis of the Mechanism of Transport and Retention of Nonaqueous-Scale-Inhibitor Treatments in Cores Using Novel Tracer Techniques

Summary In recent years, a number of nonaqueous delivery systems for scale inhibitors (SI) have been developed that are designed to be applied as low-damage, low-water-cut or pre-emptive squeeze treatments (e.g., in critical or expensive subsea wells). The mechanisms through which nonaqueous SI systems operate is an important technical issue. Only when a good understanding of the transport and retention mechanisms is developed can this be built into a model for designing such squeeze treatments (such as the SQUEEZE VI model). The experimental work in this paper focused on a specific oil soluble version of a standard pentaphos-phonate inhibitor (DETPMP), which has been described previously in the literature. Several floods have been carried out comparing corresponding nonaqueous and aqueous applications of DETPMP to better determine the main features of the transport and retention mechanism of the system. Novel core flood experiments with tracers in both the aqueous and oleic phases have been performed and are reported in this paper. Unique information is generated by designing very detailed flooding cycles and carrying out tracer floods at each stage. Results point to the formation of an immobile "emulsion-like" third phase in this system. To confirm our proposed mechanism, nonaqueous inhibitor has also been applied at zero residual water saturation (100% oil) to investigate whether or not the tailing effect (or third layer deposition) could be generated without previous oil/water partitioning of the SI. For this case, tailing of the brine tracer only was observed. Mass balance showed that there was still considerable retention of SI that was ultimately produced during the aqueous post-flush. The corresponding aqueous-inhibitor coreflood showed similar returns to that of the previous nonaqueous experiment and no retardation of either the tracer species or the metal ions in the brine. No formation damage occurred for either phase after the inhibitor was injected. A further "control" flood (no SI treatment) proved that the brine tracer tailing arose as a direct result of the treatment. The use of the tracer species in each (water and oil) phase is a genuine innovation, which provides a powerful additional technique for demonstrating the effect of chemical treatments on the flow and the retention of all fluids in the core.

0180 PATTERNS OF DEPRESSION IN SUBJECTS PUTATIVELY AT RISK FOR PSYCHOSIS

This paper presents a 3-D, non-hydrostatic, Reynolds-Averaged Navier-Stokes (RANS) model using the volume of fluid (VOF) approach to simulate dam-break flows. Good agreement is observed between the 3-D model predictions and results of dam-break experiments performed in the laboratory. The 3-D model is then applied to predict flood-wave propagation induced by the sudden failure of two flood-protection dams in Iowa, USA. Results are also compared with predictions of 2-D, hydrostatic, depth-averaged models. The 2-D model simulations using the precalibrated values of the Manning's coefficients underpredict the speed of propagation of the flood wave and the area inundated by the flood compared to the 3-D model predictions. A methodology is presented to recalibrate the 2-D model which improves the agreement with the 3-D model predictions. Simulation results also show that strong 3-D effects are generated in regions of strong curvature of the river channel, near sudden constrictions and obstacles, and during the times the mean flow direction varies significantly over the flow depth. Such 3-D effects cannot be captured by the 2-D model even after recalibration, pointing toward the need to use 3-D models for detailed flood mapping.

Volcanic Eruption Induced Floods. A Rainfall-Runoff Model Applied to the Vesuvian Region (Italy)

Explosive events are commonly accompanied or followed byheavy rains. These eruption-induced storms together with thedeposition of large amounts of ash contribute to destabilise thehydrological cycle in the areas affected by volcanic eruptions.Flooding of the region surrounding the active volcano can easilyfollow, increasing the complexity of the volcanic crisis and itsmanagement. This is particularly true in the case of Vesuvius,that is not only characterized by a dramatic volcanic hazard, butit is also located within an area that is normally prone to flood hazard. A complete assessment of the impact associated with explosive volcaniceruptions should involve a flood hazard assessment for the region.This work represents a first attempt to address the problem: atopographically based rainfall-runoff model was here applied to theVesuvian area where two main sub-basins were analysed. The modelwas applied to evaluate the role of selected parameters on the totaldischarge at the basins' outlet. These parameters were chosen amongthose likely to be affected by an explosive event and were variedthrough a reasonable range. Results confirm that the deposition oflarge amounts of ash can affect the temporal evolution of the dischargeand its maximum value, for a given precipitation event. The simulationspresented outline the need for a detailed flood forecasting study for theVesuvian area, that should be included within the hazard mitigation strategies.

Water sensitive highway design Port of Brisbane Motorway

The Port of Brisbane Motorway (PBM) has significantly raised the benchmark for water quality treatment on major road infrastructure projects in Queensland. The integration of the design and construction teams and the inclusion of stakeholders throughout the design process produced innovative solutions to overcome challenging site conditions and reduce costs. Recognised best management practices for stormwater treatment were used on this project in new and creative ways. Some treatments, such as linear wetlands, have been used for the first time on a major Queensland road project. A key environmental feature of the project has been the recycling of road pavement runoff to help preserve and enhance valuable freshwater habitat on the Bulimba Creek floodplain next to the motorway. Detailed two-dimensional flood modelling has been undertaken to ensure that the motorway has a positive impact on these wetlands during floods. The stormwater management strategy has been recognised as ‘best practice’ by Brisbane City Council, and the project won the Stormwater Industry Association (Qld) Excellence Award for 2002 in the Design and Planning Category.

Southeastern Archaic Mounds: Examples of Elaboration in a Temporally Fluctuating Environment?

Mounds dating to the mid-Holocene in the southeastern United States have challenged traditional ideas about conditions under which elaboration tends to occur. A hypothesis of wasteful behavior based on Dunnell's (1989) waste scenario and bet hedging from evolutionary ecology (Seger and Brockmann 1987) may provide a viable account for the selection of elaboration, including early mounds. Some of the variables required to formulate a satisfactory test of this and alternative explanations are examined. Paleoenvironental data suggestive of a temporally variable environment in the Southeast during the mid-Holocene are examined. More detailed flooding histories will be an essential part of future research concerned with testing these types of hypotheses.

Waterflood Surveillance in the Kuparuk River Unit With Computerized Pattern Analysis

This paper describes the computer-aided waterflood surveillance method used in the Kuparuk River field. The flood is monitored pattern by pattern, with production and injection allocations verified by comparison of measured field pressures with pressures calculated by material balance. The resulting detailed knowledge about waterflood progress has led to operational changes and workovers to optimize waterflood performance.

Flood Management for Small Urban Streams

Experiences in Princeton, N.J. are drawn on to analyze flood problems of small urban streams, including building in flood plains, increased floods due to urbanization, and accentuated erosion tendencies. A detailed survey and flood analysis were very beneficial, followed by flood plain zoning, and a requirement for flood detention storage by developers. Culverts now too small to handle increased floods constitute a defense against erosion also caused by the floods. Reconsideration of criteria for culvert design in such situations would be valuable. Federal programs fall short of meeting the rather complex problems in small urbanizing watershed.

Linear Scaling in Slug-Type Processes Application to Micellar Flooding

Abstract A relaxed scaling technique, "linear scaling," has been employed in such single-fluid injection processes as waterflooding. This paper develops processes as waterflooding. This paper develops theory and applications of linear scaling for such multiple-fluid injection processes as micellar/ polymer flooding. polymer flooding. Linear scaling demands that saturation profiles and related properties be completely defined by specifying the number of pore volumes of each fluid injected at any time in the injection history. Mobility and saturation profiles can be constructed from over-all pressure measurements and production data, respectively, from linear cores. Detailed micellar flooding experiments, in which saturation profiles, differential pressures, and production histories were measured, demonstrate production histories were measured, demonstrate that these laboratory multiple-fluid injection displacements are linearly scalable to a good approximation. We employed two micellar slugs that were used in field tests of the Maraflood oil recovery process. Introduction Rigorous mathematical scaling of displacement processes and relaxed scaling techniques have processes and relaxed scaling techniques have been discussed extensively. "Linear scaling" specifies direct correspondence among experiments when equal pore volumes of fluids have been injected, and is a special relaxed-scaling situation. It requires geometric similarity and identical rock and fluid properties for both model and prototype, but assumes that most of the dimensionless groups normally employed for scaling are unimportant for describing a displacement process. Calculation of relative permeability as presented by Welge and Johnson et al. are examples of single-fluid linear scaling applications. In multifluid chemical injection schemes, linear scaling will have limited application and must be employed with caution. In particular, fluid dispersion may not be expected to follow a linear law; this would be important in field applications. Nonlinear gravity effects could also be influential in certain geometries. In organizing saturation and pressure data from several micellar flooding experiments, it became apparent that these systems might be linearly scalable. This observation prompted clarification and better definition of linear scaling relationships for multiple-fluid injection processes. This paper is an outgrowth of that work. Its purpose is to develop linear scaling theory for multiple-fluid injection processes and demonstrate that our laboratory micellar floods scale linearly to a good approximation. THEORY Basic Considerations For a given porous medium and fluid system, a displacement process is said to be linearly scalable if fluid concentration (saturation) at any point and time is a function of only the number of pore volumes of each fluid injected with respect to that point. This is a fundamental definition. The key to applying linear scaling is understanding the concept of relative pore volumes injected with respect to a point. In one-dimensional systems (linear, radial, or spherical), this is easy to define and the practical consequences of being able to do so will be expanded later. For experimental models having heterogeneity, anisotropy, and/or non-one-dimensional boundaries (such as five-spot patterns), it is impossible to assign a fixed pore volume to a given point, since streamlines change configuration during nonunit mobility ratio displacements. Even so, by assigning an appropriate pore volume history to each point, the basic definition will still hold. One consequence of the linear scaling definition is that, in geometrically similar rocks of different size but at the same point in their relative injection history (same number of pore volumes of each given fluid injected into each rock), the saturation or concentration profiles (or contours) in all the rocks will be similar different by only a linear magnification or reduction. SPEJ p. 11