The simulation speed of two‐dimensional hydrodynamic flood models is a limiting factor when catchments are large, a considerable number of simulations is required (e.g., exploratory modeling, ...Monte‐Carlo flood simulations, or predicting probabilistic flood maps), or when there is a need for real‐time flood emergency management. Rapid Flood Models (RFMs) that rely only on topographic depressions and the water balance equation have been successfully implemented to predict maximum urban flood inundation depths within seconds to a few minutes. However, the preprocessing step (identification of depressions and their attributes) and the postprocessing step (marking up possible flow paths of flood water in between flooded depressions) of RFMs is time consuming. In this study, we developed a new fast flood inundation model based on the cellular automata (CA) approach. The new model does not require the preprocessing and postprocessing steps of RFMs and therefore can provide more simulation speed. The performance of our new model, referred to as Cellular Automata fast flood evaluation (CA‐ffé), was compared to two well‐known hydrodynamic flood models (HEC‐RAS and TUFLOW) in 20 simulation experiments conducted in five different urban subcatchments. CA‐ffé predicted maximum inundation depth with reasonable accuracy in a matter of seconds to a few minutes for a single rainfall event simulation. The CA‐ffé model performed exceptionally well in areas with low‐lying depressions. However, in areas where floodwaters had higher momentum and velocity, the model usually was not able to estimate inundation depths calculated by HEC‐RAS or TUFLOW. CA‐ffé's key drawback is also its inability to represent the temporal evolution of flooding and flow velocities. Nevertheless, its ability to provide spatial flood extents and depths in a fraction of the time compared to its hydrodynamic counterparts is a significant advancement toward exploratory approaches for water systems planning, model‐based predictive control, and real‐time flood management.
Key Points
A rapid urban flood inundation model was developed using a novel cellular automata approach and tested against detailed hydrodynamic models
Our model successfully predicted maximum inundation depth caused by excessive rain and stormwater surcharges within seconds to a few minutes
Selecting appropriate ranges for the model's parameters is crucial for model performance
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Hydraulic models play an important role in determining flood inundation areas. When considering a wide array of one‐ (1D) and two‐dimensional (2D) hydraulic models, selecting an appropriate model and ...its calibration are crucial in an accurate prediction of flood inundation. This study compares the performance of four commonly used 1D and 2D hydraulic models, including HEC‐RAS 1D, HEC‐RAS 2D, LISFLOOD‐FP diffusive, and LISFLOOD‐FP subgrid, with respect to their model structure and their sensitivity to surface roughness characterisation. Application of these models to four study reaches with different river geometry and roughness characterisation shows that for a given set of roughness condition, the geometry, including the sinuosity, reach length and floodplain width, does not affect the performance of a 1D or 2D model. Overall, the performance of a 1D model is comparable to the 2D models used in the study, with the 2D models showing slightly better results. The performance of 2D models is affected by low channel roughness, and it improves with increasing channel roughness that enables more water to enter into the floodplain. On the contrary, the performance of 1D model is positively affected with increasing floodplain roughness. When the models are evaluated for uniform versus distributed roughness characterisation in the floodplain, the uniform surface characterisation provides the best results compared to the distributed roughness characterisation.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
•Detailed municipal and island-wide flood maps were developed for PEI using the HEC-RAS 2D model.•The IDF curves were used to present rainfall intensity under 10, 25, 50, and 100 years.•Food ...inundation is expected to increase from 19% to 22% in the future.
It has been increasingly understood that pluvial flooding poses a substantial risk to numerous communities across the globe. This is especially relevant for the Canadian province of Prince Edward Island (PEI), which is susceptible to a compound flood consisting of both inland and coastal flooding. Despite various studies, a comprehensive pluvial flood model still lacks that addresses the complex interplay of compound floods. Therefore, this research aims to bridge the gap in flood mitigation by developing a pluvial flood model for PEI’s coastal communities. The Intensity-Duration-Frequency (IDF) curves under current and future climatic conditions were used to portray rainfall intensity over the study area corresponding to 10-year, 25-year, 50-year, and 100-year return periods. In addition, a hydraulic model (HEC-RAS 2D) was used to drive pluvial flood maps based on two configurations, including detailed flood maps for major municipalities and an island-wide level. The validated results showed consistency in model simulation when compared to observations. The high-resolution flood maps produced by this study can support the development of flood mitigation and adaptation strategies in PEI and other parts of the world.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Sediment transport is a complex, multi-dimensional process. With the advancement in computing power and sophistication of computer applications over recent decades, it has become possible to conduct ...detailed analysis and simulations of soil erosion and sediment transport. The primary objective of this study was to examine and predict the potential influence of human activities on sediment transport. This was achieved by analyzing sediment transport in the Saskatchewan River beneath the E.B. Campbell Dam and in the Saskatchewan River Delta. The Hydrologic Engineering Center's-River Analysis System (HEC-RAS) was deployed to ascertain the sediment transport capacity and estimate erosion, sedimentation, and riverbed changes. Cross-sectional data, flow data, and sediment data were used in conjunction with HEC-RAS. The simulation results reveal that sediment transport below the E.B. Campbell Dam is limited, leading to notable sediment erosion. The selected study area has witnessed significant erosion during high-flow periods, particularly in the event of floods. Between 2012 and 2019, the riverbed elevation at the selected survey site decreased by approximately 0.45 m. The study findings corroborate that the Saskatchewan River and its delta have been impacted by human activities. Potential erosion and deposition below the E.B. Campbell Dam have been simulated for the selected site. The aim is to provide decision-makers or related stakeholders with insight into how dam operations can be adjusted to decrease erosion while sustaining hydrological, ecological, and environmental outcomes from human activities.
•The Saskatchewan River and its delta have been influenced by human activities, climate changes, and their combined effects.•The sediment transport model via HEC-RAS evaluates the potential influences on riverbed erosion in the Saskatchewan River.•Riverbed erosion intensifies downstream of the E.B. Campbell dam.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Various factors, such as the physical condition of the area, nature, and humans, influence the phenomenon of flooding. Thus, the flood control application model will differ in each region. The ...application of flood control structurally lowers the flood water level significantly, but it changes the ecosystem around the river. The eco-hydraulic concept is a new paradigm in watershed management to reduce the impact of floods while still paying attention to river ecosystems. This study aims to integrate structural methods with eco-hydraulic concepts in flood control in small-scale watersheds. The locus is the Akelaka watershed on Halmahera Island. Watershed morphometric analysis using the ArcGIS application, hydrological analysis for five and 25-year return floods, and hydraulics testing using the HecRAS application are used. The application of this concept uses vegetation on river slopes after normalization. The results showed that flood control which combined normalization, eco-hydraulic and structural ideas in Akelaka village, showed excellent results. The potential for inundation is reduced by up to 93% for a five-year return period flood discharge and 89% for a 25-year return period flood discharge.
The development of high spatial resolution digital elevation models takes place via the use of GeoEye-1 stereo-pair imagery, providing highly accurate geometrical representations of complex riverine ...systems. The combination of geographic information systems with hydraulic models facilitates the exploitation of satellite topographic information throughout the cross-section extraction process. One-dimensional HEC-RAS and combined 1D/2D HEC-RAS models are adjusted by making use of the resulting high-resolution input. Several hydraulic simulations are effectuated in order to test how significantly DEM resolution affects hydraulic modelling results, with regard also to the model dimensionality. The ability of the combined 1D/2D model, based mainly on the high-accuracy input data, provides an accurate estimate of the flood hazard area. Flood-prone areas could take advantage of high-accuracy results and facilitate the effective management of extreme events and sufficient decision making.
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BFBNIB, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Hydrodynamic models play a key role in simulating total water level (TWL), that is, a combination of river flow, tide, surge, wind and wave‐induced water level, and representing flood inundation ...dynamics in coastal areas. An appropriate selection of two‐dimensional (2D) models that integrate riverine and estuarine interactions with ocean dynamics is crucial to generate accurate TWL predictions and assist stakeholders and federal agencies in decision making and flood emergency responses. In this study, we compare the performance of two widely used hydrodynamic models (e.g., 2D HEC‐RAS and Delft3D‐Flexible Mesh FM) with respect to their ability of predicting TWL in Delaware Bay, United States. Based on a previously established model configuration, we simulate Hurricane Sandy and Isabel that affected the Bay and led to considerable damages and economic losses. We then evaluate model capabilities with tidal analysis, compare observed vs. simulated TWL and analyze spatiotemporal variations of TWL through scenario‐based simulations. Our results suggest that atmospheric forcing input in Delft3D‐FM significantly improves TWL predictions as compared to those of 2D HEC‐RAS. Furthermore, model simulations with Delft3D‐FM can be faster than 2D HEC‐RAS by a factor of 6–10. Despite these advantages, 2D HEC‐RAS (version 5.07) is a noncommercial software easier to implement and can be a simpler alternative for modeling extreme events when atmospheric forcing is not relevant in the model domain.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Abstrak Banjir akibat limpasan sungai didaerah padat penduduk dan industri menjadi masalah berulang jika antisipasi hanya dilakukan secara minor pada saat terjadinya bencana. Berdasarkan pengamatan ...lapangan, beralihnya wilayah resapan menjadi perumahan dan industri menjadi titik awal terjadinya limpasan akibat kejenuhan tanah dan koefisien limpasan terganggu. Paradigma mengalirkan air dari sub saluran menuju badan saluran besar adalah masalah yang menjadi tabiat dan dijalankan hingga kini. Berdasarkan permasalahan tersebut, penelitian ini bertujuan untuk menganalisa limpasan yang terjadi di Sungai Way Kuripan dengan rancangan periode ulang 25 tahunan dengan menggunakan software HEC-RAS 5.0.7. Fungsi sungai sebagai penyalur air harus diiringi sebagai wilayah resapan air dengan menjadikan sungai sebagai penampung, peresap, pengalir, dan pemelihara air. Mewujudkan sistem tampung, resap, alir, dan pelihara dilakuakan dengan reboisasi daerah hulu-hilir sungai dan daerah tampungan air (Embung). Kata kunci: Limpasan, HEC-RAS, Sungai, Embung, , Abstract Flooding caused by river runoff in densely populated and industrial areas becomes a recurring problem if only minor anticipation is carried out when a disaster occurs. Based on observations, the conversion of catchment areas to housing and industry is the starting point for runoff due to soil saturation and disturbed runoff coefficients. The paradigm of channeling water from sub-channels to large channels is a problem that has become a habit and is implemented to this day. Based on these problems, this research aims to analyze the runoff that occurs in the Way Kuripan River with a return period design of 25 years using HEC-RAS 5.0.7 software. The function of the river as a water distributor must be accompanied by a water catchment area, making the river a reservoir, absorber, diverter, and maintainer of water. Creating a reservoir, absorption, diverter, and maintenance water is carried out by reforesting the upstream and downstream areas of rivers and water storage areas (retention basins). Keywords: Runoff, HEC-RAS, River,Retention basin,
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•The novelty of data-driven and HEC-RAS model for flood inundation is presented.•The accuracy in prediction and flood inundation is improved.•14 meteorological stations for 1999−2005 ...periods and TWI are used in ANN model.•Flood inundation obtained in HEC-RAS model is calibrated and validated in NDWI.
Lower Baro River, Ethiopia.
This paper presents the novelty of ANN and HEC-RAS model for flood inundation mapping in lower Baro Akobo Basin River, Ethiopia. ANN and HEC-RAS model is applied and successfully improves the accuracy of prediction and flood inundation in the region. This study uses 14 meteorological stations on a daily basis for 1999−2005 and 2006−2008 periods, and Topographical Wetness Index (TWI) to the train and test the model respectively. The runoff time series obtained in ANN model is linked to HEC-RAS and the flood depths were generated. The flood inundation generated in HEC-RAS model result was calibrated and validated in Normal Difference Water Index (NDWI).
As the inundation map generated from the runoff values of ANN model reveals, the lower Baro river forms huge inundation depth up to 250 cm. The performance the ANN model was evaluated using Nash-Sutcliffe Efficiency (NSE = 0.86), PBIAS = 8.2 % and R2 = 0.91 and NSE = 0.88, PBIAS = 8.5 % and R2 = 0.93 during the training and testing periods respectively. The generated inundation areas in HEC-RAS and the water bodies delineated in NDWI were covered with 94.6 % and 96 % as overlapping areas during the calibration and validation periods respectively. Therefore, it is concluded that the integration of the ANN approach with the HEC-RAS model has improved the prediction accuracy in traditional flood forecasting methods.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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