scholarly journals Assessing the impact of different sources of topographic data on 1-D hydraulic modelling of floods

2015 ◽  
Vol 19 (1) ◽  
pp. 631-643 ◽  
Author(s):  
A. Md Ali ◽  
D. P. Solomatine ◽  
G. Di Baldassarre
Keyword(s):  
Low Cost ◽  
Water Levels ◽  
Test Model ◽  
Flood Inundation ◽  
Model Accuracy ◽  
Flood Water ◽  
Hydraulic Models ◽  
Topographic Data ◽  
Ground Survey ◽  
Different Sources

Abstract. Topographic data, such as digital elevation models (DEMs), are essential input in flood inundation modelling. DEMs can be derived from several sources either through remote sensing techniques (spaceborne or airborne imagery) or from traditional methods (ground survey). The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), the Shuttle Radar Topography Mission (SRTM), the light detection and ranging (lidar), and topographic contour maps are some of the most commonly used sources of data for DEMs. These DEMs are characterized by different precision and accuracy. On the one hand, the spatial resolution of low-cost DEMs from satellite imagery, such as ASTER and SRTM, is rather coarse (around 30 to 90 m). On the other hand, the lidar technique is able to produce high-resolution DEMs (at around 1 m), but at a much higher cost. Lastly, contour mapping based on ground survey is time consuming, particularly for higher scales, and may not be possible for some remote areas. The use of these different sources of DEM obviously affects the results of flood inundation models. This paper shows and compares a number of 1-D hydraulic models developed using HEC-RAS as model code and the aforementioned sources of DEM as geometric input. To test model selection, the outcomes of the 1-D models were also compared, in terms of flood water levels, to the results of 2-D models (LISFLOOD-FP). The study was carried out on a reach of the Johor River, in Malaysia. The effect of the different sources of DEMs (and different resolutions) was investigated by considering the performance of the hydraulic models in simulating flood water levels as well as inundation maps. The outcomes of our study show that the use of different DEMs has serious implications to the results of hydraulic models. The outcomes also indicate that the loss of model accuracy due to re-sampling the highest resolution DEM (i.e. lidar 1 m) to lower resolution is much less than the loss of model accuracy due to the use of low-cost DEM that have not only a lower resolution, but also a lower quality. Lastly, to better explore the sensitivity of the 1-D hydraulic models to different DEMs, we performed an uncertainty analysis based on the GLUE methodology.

scholarly journals Assessing the impact of different sources of topographic data on 1-D hydraulic modelling of floods

2014 ◽  
Vol 11 (7) ◽  
pp. 7375-7408 ◽  
Author(s):  
A. Md Ali ◽  
D. P. Solomatine ◽  
G. Di Baldassarre
Keyword(s):  
Thermal Emission ◽  
Low Cost ◽  
Water Levels ◽  
Flood Inundation ◽  
Model Accuracy ◽  
Hydraulic Models ◽  
Topographic Data ◽  
Ground Survey ◽  
The Impact ◽  
Different Sources

Abstract. Topographic data, such as digital elevation models (DEMs), are essential input in flood inundation modelling. DEMs can be derived from several sources either through remote sensing techniques (space-borne or air-borne imagery) or from traditional methods (ground survey). The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), the Shuttle Radar Topography Mission (SRTM), the Light Detection and Ranging (LiDAR), and topographic contour maps are some of the most commonly used sources of data for DEMs. These DEMs are characterized by different precision and accuracy. On the one hand, the spatial resolution of low-cost DEMs from satellite imagery, such as ASTER and SRTM, is rather coarse (around 30–90 m). On the other hand, LiDAR technique is able to produce a high resolution DEMs (around 1m), but at a much higher cost. Lastly, contour mapping based on ground survey is time consuming, particularly for higher scales, and may not be possible for some remote areas. The use of these different sources of DEM obviously affects the results of flood inundation models. This paper shows and compares a number of hydraulic models developed using HEC-RAS as model code and the aforementioned sources of DEM as geometric input. The study was carried out on a reach of the Johor River, in Malaysia. The effect of the different sources of DEMs (and different resolutions) was investigated by considering the performance of the hydraulic models in simulating flood water levels as well as inundation maps. The outcomes of our study show that the use of different DEMs has serious implications to the results of hydraulic models. The outcomes also indicates the loss of model accuracy due to re-sampling the highest resolution DEM (i.e. LiDAR 1 m) to lower resolution are much less compared to the loss of model accuracy due to the use of low-cost DEM that have not only a lower resolution, but also a lower quality. Lastly, to better explore the sensitivity of the hydraulic models to different DEMs, we performed an uncertainty analysis based on the GLUE methodology.

Flood Inundation Analysis and Mitigation with a Coupled 1D-2D Hydraulic Model: A Case Study in Kochi, Japan

2015 ◽  
Vol 10 (6) ◽  
pp. 1099-1109 ◽  
Author(s):  
M. A. C. Niroshinie ◽  
◽  
Yasuo Nihei ◽  
Kazuaki Ohtsuki ◽  
Shoji Okada ◽  
...  
Keyword(s):  
Flood Plain ◽  
Water Levels ◽  
Flood Inundation ◽  
Two Dimensional ◽  
Hydraulic Models ◽  
Mountain Watershed ◽  
Maximum Water ◽  
Kochi Prefecture ◽  
Inundation Model

Coupled one and two-dimensional (1D-2D) hydraulic models play a significant role in analyzing flooding problems to find possible solutions as they can reproduce the actual situations relatively accurately. This paper summarizes approaches to flood inundation analysis and mitigation with coupled 1D-2D hydraulic models of a small mountain watershed in Japan. A detailed flood inundation model including the effects of drainages, pumping, inflow from mountain sub-watersheds and flood gates is developed using coupled 1D-2D hydraulic models. The model is applied to the inundation in Kubokawa, a small town in Kochi Prefecture, Japan on August 9-10, 2014. Simulated and observed maximum water levels along the river and maximum inundations in the flood plain are compared and found to be consistent. Causes of the flooding and percentage of contribution are quantitatively identified, and countermeasures to reduce the effects of flooding are proposed.

scholarly journals Flood Inundation Assessment in the Low-Lying River Basin Considering Extreme Rainfall Impacts and Topographic Vulnerability

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 896
Author(s):  
Thanh Thu Nguyen ◽  
Makoto Nakatsugawa ◽  
Tomohito J. Yamada ◽  
Tsuyoshi Hoshino
Keyword(s):  
River Basin ◽  
Extreme Rainfall ◽  
Flood Damage ◽  
Water Levels ◽  
Flood Inundation ◽  
Inundation Area ◽  
Inundation Depth ◽  
Study Results ◽  
Inundation Duration ◽  
Short Time

This study aims to evaluate the change in flood inundation in the Chitose River basin (CRB), a tributary of the Ishikari River, considering the extreme rainfall impacts and topographic vulnerability. The changing impacts were assessed using a large-ensemble rainfall dataset with a high resolution of 5 km (d4PDF) as input data for the rainfall–runoff–inundation (RRI) model. Additionally, the prediction of time differences between the peak discharge in the Chitose River and peak water levels at the confluence point intersecting the Ishikari River were improved compared to the previous study. Results indicate that due to climatic changes, extreme river floods are expected to increase by 21–24% in the Ishikari River basin (IRB), while flood inundation is expected to be severe and higher in the CRB, with increases of 24.5, 46.5, and 13.8% for the inundation area, inundation volume, and peak inundation depth, respectively. Flood inundation is likely to occur in the CRB downstream area with a frequency of 90–100%. Additionally, the inundation duration is expected to increase by 5–10 h here. Moreover, the short time difference (0–10 h) is predicted to increase significantly in the CRB. This study provides useful information for policymakers to mitigate flood damage in vulnerable areas.

scholarly journals A low-cost technique to measure bank erosion proces ses along middle-size river reaches

2018 ◽  
Author(s):  
Gonzalo Duró ◽  
Alessandra Crosato ◽  
Maarten G. Kleinhans ◽  
Wim S. J. Uijttewaal
Keyword(s):  
Laser Scanning ◽  
Spatial Scales ◽  
Low Cost ◽  
Bank Erosion ◽  
Water Levels ◽  
Small Scale ◽  
Observation Distance ◽  
River Bank ◽  
Erosion Processes ◽  
Rtk Gps

Abstract. Diverse methods are currently available to measure river bank erosion at broad-ranging temporal and spatial scales. Yet, no technique provides low-cost and high-resolution to survey small-scale bank processes along a river reach. We investigate the capabilities of Structure-from-Motion photogrammetry applied with imagery from an Unmanned Aerial Vehicle (UAV) to describe the evolution of riverbank profiles in middle-size rivers. The bank erosion cycle is used as a reference to assess the applicability of different techniques. We surveyed 1.2 km of a restored bank of the Meuse River eight times within a year, combining different photograph perspectives and overlaps to identify an efficient UAV flight to monitor banks. The accuracy of the Digital Surface Models (DSMs) was evaluated compared with RTK GPS points and an Airborne Laser Scanning (ALS) of the whole reach. An oblique perspective with eight photo overlaps was sufficient to achieve the highest relative precision to observation distance of ~1:1400, with 10 cm error range. A complementary nadiral view increased coverage behind bank toe vegetation. The DSM and ALS had comparable accuracies except on banks, where the latter overestimates elevations. Sequential DSMs captured signatures of the erosion cycle such as mass failures, slump-block deposition, and bank undermining. Although this technique requires low water levels and banks without dense vegetation, it is a low-cost method to survey reach-scale riverbanks in sufficient resolution to quantify bank retreat and identify morphological features of the bank failure and erosion processes.

scholarly journals Increase of flood water levels on the middle Danube

2015 ◽  
Vol 366 ◽  
pp. 145-146
Author(s):  
P. Pekarova ◽  
P. Miklanek ◽  
J. Pekar
Keyword(s):  
Water Levels ◽  
Flood Water

An Investigation of Cavitation and Suction Vortices Behavior in Pump Sump

2011 ◽  
Author(s):  
Won-Tae Kang ◽  
Ki Han Yu ◽  
Seung Yeob Lee ◽  
Byeong Rog Shin
Keyword(s):  
Experimental Investigation ◽  
Numerical Analysis ◽  
Test Procedure ◽  
Three Dimensional ◽  
Water Levels ◽  
National Standard ◽  
Piping System ◽  
Test Model ◽  
Grid Systems ◽  
Volume Method

A numerical and an experimental investigation on a suction vortices including cavitation, free vortices and subsurface vortices behavior in the model sump system with multi-intakes is performed at several flow rates and water levels. A test model sump and piping system were designed based on Froude similitude for the prototype of the recommended structure layout by HI-9.8 American National Standard for Pump Intake Design of the Hydraulic Institute. An experiment is performed according to the sump model test procedure of Hyosung Goodsprings, Inc. A numerical analysis of three dimensional multiphase flows through the model sump is performed by using the finite volume method of the CFX code with multi-block structured grid systems. A k-ω Shear Stress Transport turbulence model and the Rayleigh-Plesset cavitation model are used for solving turbulence cavitating flow. Several types of free surface and submerged vortex which occurs with each different water level are identified through the experimental investigation. From the numerical analysis, the vortices are reproduced and their formation, growing, shedding and detailed vortex structures are investigated. To reduce abnormal vortices, an anti-vortex device is considered and its effect is investigated and discussed.

THE TRANSIENT EFFECTS OF FLOOD WATER ON A WARSHIP IN CALM WATER IMMEDIATELY FOLLOWING DAMAGE

2021 ◽  
Vol 152 (A4) ◽  
Author(s):  
G J Macfarlane ◽  
M R Renilson ◽  
T Turner
Keyword(s):  
Equilibrium Position ◽  
Upright Position ◽  
Water Levels ◽  
Transient Effects ◽  
Roll Damping ◽  
Transient Motion ◽  
Flood Water ◽  
Transient Behaviour ◽  
Calm Water ◽  
The Way

The safety of a ship which is damaged below the waterline will depend on the way water floods into the internal compartments. The water will cause the ship to take on an angle of heel and trim which will further affect the flooding into the compartments. The ship’s equilibrium position in calm water can be predicted using hydrostatic theory, however at present it is difficult to predict the transient behaviour between the initial upright position of the ship and its final equilibrium. In some cases, the transient motion may cause a capsize prior to a possible equilibrium position being reached. This paper describes an investigation of this phenomenon using a model of a warship with simplified, typical internal geometry. With the model initially stationary, a rapid damage event was generated, and the global motions measured, along with the water levels in some of the internal compartments, as functions of time. Immediately after the damage occurred the model rolled to starboard (towards the damage). It then rolled to port (away from the damage) before eventually returning to starboard and settling at its equilibrium value. In all the tests conducted the equilibrium heel angle was less than that reached during the initial roll to starboard. This implies that the roll damping, and the way in which the water floods into the model immediately following the damage, could both have a very important influence on the likelihood of survival.

Assimilation of inundation extent observations into a flood forecasting system:  a tempered particle filter for combatting degeneracy and sample impoverishment.

2021 ◽  
Author(s):  
Concetta Di Mauro ◽  
Renaud Hostache ◽  
Patrick Matgen ◽  
Peter Jan van Leeuwen ◽  
Nancy Nichols ◽  
...  
Keyword(s):  
Particle Filter ◽  
Main Idea ◽  
Water Levels ◽  
Smooth Transition ◽  
Observation Data ◽  
Flood Inundation ◽  
State Variables ◽  
Time Step ◽  
Radar Images ◽  
Forecasting System

<p>Data assimilation uses observation for updating model variables and improving model output accuracy. In this study, flood extent information derived from Earth Observation data (namely Synthetic Aperture Radar images) are assimilated into a loosely coupled flood inundation forecasting system via a Particle Filter (PF). A previous study based on a synthetic experiment has shown the validity and efficiency of a recently developed PF-based assimilation framework allowing to effectively integrate remote sensing-derived probabilistic flood inundation maps into a coupled hydrologic-hydraulic model. One of the main limitations of this recent framework based on sequential importance sampling is the sample degeneracy and impoverishment, as particles loose diversity and only few of them keep a substantial importance weight in the posterior distribution. In order to circumvent this limitation, a new methodology is adopted and evaluated: a tempered particle filter. The main idea is to update a set of state variables, namely through a smooth transition (iterative and adaptative process). To do so, the likelihood is factorized using small tempering factors. Each iteration includes subsequent resampling and mutation steps using a Monte Carlo Metropolis Hasting algorithm. The mutation step is required to regain diversity between the particles after the resampling. The new methodology is tested using synthetic twin experiments and the results are compared to the one obtained with the previous approach. The new proposed method enables to substantially improve the predictions of streamflow and water levels within the hydraulic domain at the assimilation time step. Moreover, the preliminary results show that these improvements are longer lasting. The proposed tempered particle filter also helps in keeping more diversity within the ensemble.</p>

scholarly journals The use of wastes (organic and inorganic) in land restoration in relation to their characteristics and cost

2019 ◽  
Vol 37 (5) ◽  
pp. 502-507 ◽  
Author(s):  
Ana Pérez-Gimeno ◽  
José Navarro-Pedreño ◽  
María Belén Almendro-Candel ◽  
Ignacio Gómez ◽  
Antonis A Zorpas
Keyword(s):  
Sewage Sludge ◽  
Low Cost ◽  
Organic Matter Content ◽  
Palm Tree ◽  
Land Restoration ◽  
Sludge Compost ◽  
Sewage Sludge Compost ◽  
Soil Rehabilitation ◽  
The Cost ◽  
Different Sources

The great extent of degraded soils in southeast Spain makes it necessary to carry out restoration and rehabilitation strategies. In addition, the great amount of wastes produced need to be properly managed. Several types of wastes and amendments (organic and inorganic) can be applied for soil rehabilitation and land restoration. When large areas must be restored several aspects should be considered, such as availability of the waste, its characteristics, and transport. This research focuses on the characterization and the cost of 12 waste types and amendments (such as sewage sludge compost, brown peat, black peat, fertilized peat, earthworm humus, straw hay, palm tree leaves, pine bark, exfoliated vermiculite, expanded perlite, limestone outcrops, and volcanic crushed stones) obtained from four different sources. All of them were characterized following the UNE standards for soil amendments and the cost was obtained as a mean value of four different sources. The results indicate a great variability of properties between organic and inorganic materials, as was expected. Depending on the type of restoration, the characteristics, and the cost, the materials can be selected for an adequate purpose. Sewage sludge compost is a good alternative for application in large areas related to its characteristics (organic matter content and nutrient availability) and low cost. For inorganic amendments, natural limestone outcrops were the low-cost alternative. The use of both wastes (composted sewage sludge and limestone raw materials) for soil rehabilitation can facilitate the reduction of landfill disposal and add value for these wastes. Moreover, the results are very useful for scientists and engineers who deal with the development of rehabilitation and restoration strategies.

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