scholarly journals Flood mapping in small ungauged basins: a comparison of different approaches for two case studies in Slovakia

2018 ◽  
Vol 50 (1) ◽  
pp. 379-392 ◽  
Author(s):  
Andrea Petroselli ◽  
Matej Vojtek ◽  
Jana Vojteková
Keyword(s):  
Hydrologic Modeling ◽  
Hydraulic Modeling ◽  
Flood Mapping ◽  
Ungauged Basins ◽  
Dem Resolution ◽  
Digital Elevation ◽  
Design Hydrographs ◽  
Elevation Model ◽  
Event Based ◽  
Relief Area

Abstract Flood mapping is a crucial element of flood risk management. In small and ungauged basins, empirical and regionalization approaches are often adopted to estimate the design hydrographs that represent input data in hydraulic models. In this study, two basins were selected in Slovakia and different methodologies for flood mapping were tested highlighting the role of digital elevation model (DEM) resolution, hydrologic modeling and the hydraulic model. Two DEM resolutions (2 m and 20 m) were adopted. Two hydrologic approaches were employed: a regional formula for peak flow estimation and the EBA4SUB model. Two hydraulic approaches (HEC-RAS and FLO-2D) were selected. Different combinations of hydrologic and hydraulic modeling were tested, under different spatial resolutions. Regarding the DEM resolution, results showed its fundamental importance in the low relief area while its effect was secondary in the moderate relief area. Regarding the hydrologic modeling, results confirmed that it affects the results of the flood areas in the same way independently of DEM resolution and that when using event-based models, the hydrograph shape determination is fundamental. Regarding the hydraulic modeling, this was the step where major differences in the flood area estimation were found.

scholarly journals UAV-DEMs for Small-Scale Flood Hazard Mapping

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1717 ◽  
Author(s):  
Antonio Annis ◽  
Fernando Nardi ◽  
Andrea Petroselli ◽  
Ciro Apollonio ◽  
Ettore Arcangeletti ◽  
...  
Keyword(s):  
High Resolution ◽  
Hydrologic Modeling ◽  
Flood Hazard ◽  
Hydraulic Modeling ◽  
Flood Frequency ◽  
Hazard Mapping ◽  
Small Scale ◽  
Ungauged Basins ◽  
Modeling Framework ◽  
Flood Simulations

Devastating floods are observed every year globally from upstream mountainous to coastal regions. Increasing flood frequency and impacts affect both major rivers and their tributaries. Nonetheless, at the small-scale, the lack of distributed topographic and hydrologic data determines tributaries to be often missing in inundation modeling and mapping studies. Advances in Unmanned Aerial Vehicle (UAV) technologies and Digital Elevation Models (DEM)-based hydrologic modeling can address this crucial knowledge gap. UAVs provide very high resolution and accurate DEMs with low surveying cost and time, as compared to DEMs obtained by Light Detection and Ranging (LiDAR), satellite, or GPS field campaigns. In this work, we selected a LiDAR DEM as a benchmark for comparing the performances of a UAV and a nation-scale high-resolution DEM (TINITALY) in representing floodplain topography for flood simulations. The different DEMs were processed to provide inputs to a hydrologic-hydraulic modeling chain, including the DEM-based EBA4SUB (Event-Based Approach for Small and Ungauged Basins) hydrologic modeling framework for design hydrograph estimation in ungauged basins; the 2D hydraulic model FLO-2D for flood wave routing and hazard mapping. The results of this research provided quantitative analyses, demonstrating the consistent performances of the UAV-derived DEM in supporting affordable distributed flood extension and depth simulations.

scholarly journals Evaluation of Reliable Digital Elevation Model Resolution for TOPMODEL in Two Mountainous Watersheds, South Korea

2019 ◽  
Vol 9 (18) ◽  
pp. 3690 ◽  
Author(s):  
Daeryong Park ◽  
Huan-Jung Fan ◽  
Jun-Jie Zhu ◽  
Sang-Eun Oh ◽  
Myoung-Jin Um ◽  
...  
Keyword(s):  
South Korea ◽  
Cell Size ◽  
Digital Elevation Model ◽  
River Basin ◽  
Grid Cell ◽  
Dem Resolution ◽  
Digital Elevation ◽  
Mountainous Watersheds ◽  
Elevation Model ◽  
Digital Elevation Model Resolution

This study analyzed the result of parameter optimization using the digital elevation model (DEM) resolution in the TOPography-based hydrological MODEL (TOPMODEL). Also, this study investigated the sensitivity of the TOPMODEL efficiency by applying the varying resolution of the DEM grid cell size. This work applied TOPMODEL to two mountainous watersheds in South Korea: the Dongkok watershed in the Wicheon river basin and the Ieemokjung watershed in the Pyeongchang river basin. The DEM grid cell sizes were 5, 10, 20, 40, 80, 160, and 300 m. The effect of DEM grid cell size on the runoff was investigated by using the DEM grid cell size resolution to optimize the parameter sets. As the DEM grid cell size increased, the estimated peak discharge was found to increase based on different parameter sets. In addition, this study investigated the DEM grid cell size that was most reliable for use in runoff simulations with various parameter sets in the experimental watersheds. The results demonstrated that the TOPMODEL efficiencies in both the Dongkok and Ieemokjung watersheds rarely changed up to a DEM grid-size resolution of about 40 m, but the TOPMODEL efficiencies changed with the coarse resolution as the parameter sets were changed. This study is important for understanding and quantifying the modeling behaviors of TOPMODEL under the influence of DEM resolution based on different parameter sets.

scholarly journals Effects of digital elevation model resolution on topography-based runoff simulation under uncertainty

2014 ◽  
Vol 16 (6) ◽  
pp. 1343-1358 ◽  
Author(s):  
L. Cui ◽  
Y. P. Li ◽  
G. H. Huang ◽  
Y. Huang
Keyword(s):  
Water Resources ◽  
Digital Elevation Model ◽  
Water Resources Management ◽  
Rainfall Runoff ◽  
Runoff Simulation ◽  
Resources Management ◽  
Dem Resolution ◽  
Analysis Technique ◽  
Digital Elevation ◽  
Elevation Model

Topography plays a critical role in controlling water dispersion and soil movement in hydrologic modeling for water resources management with raster-based digital elevation model (DEM). This study aims to model effects of DEM resolution on runoff simulation through coupling fuzzy analysis technique with a topography based rainfall–runoff model (TOPMODEL). Different levels of DEM grid sizes between 30 m and 200 m are examined, and the results indicate that 30 m DEM resolution is the best for all catchments. Results demonstrate that the DEM resolution could have significant influence on the TOPMODEL rainfall–runoff simulation. Fuzzy analysis technique is used to further examine the uncertain DEM resolution based on considering Nash, sum of squared error, and sum of absolute error values of TOPMODEL. The developed model is calibrated and validated against observed flow during the period 2010–2012, and generally performed acceptably for model Nash–Sutcliffe value. The proposed method is useful for studying hydrological processes of watershed associated with topography uncertainty and providing support for identifying proper water resources management strategy.

Flood mapping in ungauged basins using fully continuous hydrologic–hydraulic modeling

2013 ◽  
Vol 487 ◽  
pp. 39-47 ◽  
Author(s):  
Salvatore Grimaldi ◽  
Andrea Petroselli ◽  
Ettore Arcangeletti ◽  
Fernando Nardi
Keyword(s):  
Hydraulic Modeling ◽  
Flood Mapping ◽  
Ungauged Basins

scholarly journals Influence of different sources of topographic data on flood mapping: urban area São Vendelino municipality, southern Brazil

RBRH ◽  
2020 ◽  
Vol 25 ◽  
Author(s):  
Fernando Campo Zambrano ◽  
Masato Kobiyama ◽  
Marco Alésio Figueiredo Pereira ◽  
Gean Paulo Michel ◽  
Fernando Mainardi Fan
Keyword(s):  
Cross Sections ◽  
Field Survey ◽  
Flood Mapping ◽  
Mean Velocity ◽  
Topographic Data ◽  
Digital Elevation ◽  
Wetted Area ◽  
Elevation Model ◽  
Best Fit ◽  
Different Sources

ABSTRACT Generally, the base for any flood mapping is the topography information whose resolution determines the map accuracy. Furthermore, river bathymetry in detail and the type of used model are also relevant. Therefore, the objective of the present study was to evaluate the influence of different sources of topographic data on the flood mapping by using the CAESAR-Lisflood model and three Digital Elevation Model (DEM) configurations, among which two were freely available, and the other was generated with field survey (topography and bathymetry). First, the resolution and precision of each DEM were evaluated, from the comparison of different cross-sections, besides the variation of the wetted area and absolute value of the relative error in mean velocity as a function of depth. Subsequently, after elaborating flood maps with each DEM, the results were compared in terms of flood area, mean flood width and flow depth. It is observed that the more accurate resolution, the smaller the flood area becomes. The flood map elaborated with the DEM through field survey had the best fit to the observed area. However the relation between the topographic resolutions and flow-depths was not clear in obtained results.

scholarly journals Reducing scale dependence in TOPMODEL using a dimensionless topographic index

2009 ◽  
Vol 13 (12) ◽  
pp. 2399-2412 ◽  
Author(s):  
A. Ducharne
Keyword(s):  
Cell Size ◽  
Scale Dependence ◽  
Contour Length ◽  
Topographic Index ◽  
Dem Resolution ◽  
Unit System ◽  
Topographic Slope ◽  
Digital Elevation ◽  
Numerical Effect ◽  
Elevation Model

Abstract. This paper stems from the fact that the topographic index used in TOPMODEL is not dimensionless. In each pixel i in a catchment, it is defined as xi=ln(ai/Si), where ai is the specific contributing area per unit contour length and Si is the topographic slope. In the SI unit system, ai/Si is in meters, and the unit of xi is problematic. We propose a simple solution in the widespread cases where the topographic index is computed from a regular raster digital elevation model (DEM). The pixel length C being constant, we can define a dimensionless topographic index yi=xi-lnC. Reformulating TOPMODEL equations to use yi instead of xi helps giving the units of all their terms and emphasizes the scale dependence of these equations via the explicit use of C outside from the topographic index, in what can be defined as the transmissivity at saturation per unit contour length T0/C. The term lnC defines the numerical effect of DEM resolution, which contributes to shift the spatial mean x of the classical topographic index when the DEM cell size C varies. A key result is that both the spatial mean y of the dimensionless index and T0/C are much more stable with respect to DEM resolution than their counterparts x and T0 in the classical framework. This shows the importance of the numerical effect in the dependence of the classical topographic index to DEM resolution, and reduces the need to recalibrate TOPMODEL when changing DEM resolution.

scholarly journals Estimation of synthetic flood design hydrographs using a distributed rainfall–runoff model coupled with a copula-based single storm rainfall generator

2014 ◽  
Vol 14 (7) ◽  
pp. 1819-1833 ◽  
Author(s):  
A. Candela ◽  
G. Brigandì ◽  
G. T. Aronica
Keyword(s):  
Curve Number ◽  
Geographical Information ◽  
Rainfall Runoff ◽  
Unit Hydrograph ◽  
Digital Elevation ◽  
Design Hydrographs ◽  
Rainfall Runoff Model ◽  
Storm Rainfall ◽  
Elevation Model ◽  
Runoff Model

Abstract. In this paper a procedure to derive synthetic flood design hydrographs (SFDH) using a bivariate representation of rainfall forcing (rainfall duration and intensity) via copulas, which describes and models the correlation between two variables independently of the marginal laws involved, coupled with a distributed rainfall–runoff model, is presented. Rainfall–runoff modelling (R–R modelling) for estimating the hydrological response at the outlet of a catchment was performed by using a conceptual fully distributed procedure based on the Soil Conservation Service – Curve Number method as an excess rainfall model and on a distributed unit hydrograph with climatic dependencies for the flow routing. Travel time computation, based on the distributed unit hydrograph definition, was performed by implementing a procedure based on flow paths, determined from a digital elevation model (DEM) and roughness parameters obtained from distributed geographical information. In order to estimate the primary return period of the SFDH, which provides the probability of occurrence of a hydrograph flood, peaks and flow volumes obtained through R–R modelling were treated statistically using copulas. Finally, the shapes of hydrographs have been generated on the basis of historically significant flood events, via cluster analysis. An application of the procedure described above has been carried out and results presented for the case study of the Imera catchment in Sicily, Italy.

scholarly journals The Importance of Digital Elevation Model Selection in Flood Simulation and a Proposed Method to Reduce DEM Errors: A Case Study in Shanghai

2021 ◽  
Author(s):  
Kepeng Xu ◽  
Jiayi Fang ◽  
Yongqiang Fang ◽  
Qinke Sun ◽  
Chengbo Wu ◽  
...  
Keyword(s):  
Open Access ◽  
Critical Role ◽  
Flood Management ◽  
Hydraulic Modeling ◽  
Flood Mapping ◽  
Flood Inundation ◽  
Flood Simulation ◽  
Urban Flood ◽  
Digital Elevation ◽  
Flood Inundation Mapping

AbstractDigital Elevation Models (DEMs) play a critical role in hydrologic and hydraulic modeling. Flood inundation mapping is highly dependent on the accuracy of DEMs. Various vertical differences exist among open access DEMs as they use various observation satellites and algorithms. The problem is particularly acute in small, flat coastal cities. Thus, it is necessary to assess the differences of the input of DEMs in flood simulation and to reduce anomalous errors of DEMs. In this study, we first conducted urban flood simulation in the Huangpu River Basin in Shanghai by using the LISFLOOD-FP hydrodynamic model and six open-access DEMs (SRTM, MERIT, CoastalDEM, GDEM, NASADEM, and AW3D30), and analyzed the differences in the results of the flood inundation simulations. Then, we processed the DEMs by using two statistically based methods and compared the results with those using the original DEMs. The results show that: (1) the flood inundation mappings using the six original DEMs are significantly different under the same simulation conditions—this indicates that only using a single DEM dataset may lead to bias of flood mapping and is not adequate for high confidence analysis of exposure and flood management; and (2) the accuracy of a DEM corrected by the Dixon criterion for predicting inundation extent is improved, in addition to reducing errors in extreme water depths—this indicates that the corrected datasets have some performance improvement in the accuracy of flood simulation. A freely available, accurate, high-resolution DEM is needed to support robust flood mapping. Flood-related researchers, practitioners, and other stakeholders should pay attention to the uncertainty caused by DEM quality.

scholarly journals DEM Resolution Impact on the Estimation of the Physical Characteristics of Watersheds by Using SWAT

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Waranyu Buakhao ◽  
Anongrit Kangrang
Keyword(s):  
Assessment Tool ◽  
Swat Model ◽  
Large Area ◽  
Mountain Area ◽  
Watershed Characteristics ◽  
Watershed Area ◽  
Dem Resolution ◽  
Digital Elevation ◽  
Elevation Model ◽  
The Impact

A digital elevation model (DEM) is an important spatial input for automatic extraction of topographic parameters for the soil and water assessment tool (SWAT). The objective of this study was to investigate the impact of DEM resolution (from 5 to 90 m) on the delineation process of a SWAT model with two types of watershed characteristics (flat area and mountain area) and three sizes of watershed area (about 20,000, 200,000, and 1,500,000 hectares). The results showed that the total lengths of the streamline, main channel slope, watershed area, and area slope were significantly different when using the DEM datasets to delineate. Delineation using the SRTM DEM (90 m), ASTER DEM (30 m), and LDD DEM (5 m) for all watershed characteristics showed that the watershed sizes and shapes obtained were only slightly different, whereas the area slopes obtained were significantly different. The total lengths of the generated streams increased when the resolution of the DEM used was higher. The stream slopes obtained using the small area sizes were insignificant, whereas the slopes obtained using the large area sizes were significantly different. This suggests that water resource model users should use the ASTER DEM as opposed to a finer resolution DEM for model input to save time for the model calibration and validation.

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