Many of the world‐rivers are often ungauged or poorly gauged due to inadequate streamflow monitoring networks. Even with the limited available monitoring stations, only a few of them monitor both ...stage and discharge data. But when there is a need for estimation of discharges at a gauging station, where only stage data is monitored, one may employ a reverse routing technique using the stage data monitored at a nearby downstream gauging station. This study develops a novel single‐parameter reverse‐stage routing (RSR) model based on the second‐order approximate water surface gradient governing equation to estimate stage and discharge at any scantily‐gauged upstream river section using the known stage information available at the downstream section. A novel criterion is also developed for checking the applicability of the RSR model. Reverse routing experiments, carried out by the RSR model using different hypothetical downstream stage hydrographs in a number of hypothetical trapezoidal and rectangular channel reaches to reproduce the benchmark upstream stage and discharge hydrographs, demonstrate the good performance of the RSR model with the Nash–Sutcliffe Efficiency >98%, absolute volume conservation error <1.5%, and an absolute error in peak ≤1%. Subsequently, the RSR model was tested for three real‐river case studies in India and Italy with good reproduction performances, and along with the development of the corresponding normal rating curves at the upstream river sections. The study results reveal that the parsimonious RSR model has good potential for solving reverse routing problems with stable numerical solutions for rivers under ungauged and scantily‐gauged scenarios.
Plain Language Summary
The discharge and flow depth variables at an upstream section of a river reach are often required for flood management and operating the downstream hydraulic control structures. However, many world‐rivers have poor streamflow monitoring infrastructure, and sometimes, only stage data at the downstream section of a reach are available. As the existing methods mostly use discharge as the operating variable, this study is aimed at developing an approach involving stage as an operating variable. Hence, the current study proposes a novel physically based parsimonious Reverse stage‐routing model for obtaining the upstream flow depth and the corresponding discharge, thus establishing the normal rating curve at the ungauged section, meant for field use. A novel applicability criterion is also advocated to check the failure of the routed solutions. Conclusively, the developed model has an excellent potential to establish normal rating curves at an ungauged or scantily‐gauged upstream river section for field applications by field engineers and water resources managers.
Key Points
Based on the second‐order approximate water surface gradient equation, developed a novel reverse‐stage routing model with lateral flow
Developed a novel applicability criterion ensuring stable stage‐discharge solutions at ungauged/scantily‐gauged upstream river sections
In hypothetical and real‐river cases, it efficiently solves reverse routing problems and can establish normal rating curves
Extreme floods have become common in Asian cities, with recent increases in urbanization and extreme rainfall driving increasingly severe and frequent events. Understanding the flood dynamic is ...essential for developing strategies to reduce risk and damage, thus ensuring the city’s protection. Channel roughness is a sensitive parameter in developing a hydraulic model for flood forecasting and flood inundation mapping. A High-resolution 2D HEC-RAS model was used to simulate the flood events of 1994, 1998, 2002, 2006, and 2015. The calibrated model, in terms of channel roughness, has been used to simulate the flood for the year 2006 in the river. The performance of the calibrated HEC-RAS-based model has been accessed by capturing the flood peaks of observed and simulated floods and computation of root mean squared error (RMSE) for the intermediated gauging stations on the lower Tapi River. Results revealed that there is good agreement between simulated and observed floods.
Abstract One of the most perilous natural hazards is flooding resulting from dam failure, which can devastate downstream infrastructure and lead to significant human casualties. In recent years, the ...frequency of flash floods in the northern part of Nicosia, Cyprus, has increased. This area faces increased risk as it lies downstream of the Kanlikoy Dam, an aging earth-fill dam constructed over 70 years ago. In this study, we aim to assess potential flood hazards stemming from three distinct failure scenarios: piping, 100-year rainfall, and probable maximum precipitation (PMP). To achieve this, HEC-HMS hydrologic model findings were integrated into 2D HEC-RAS hydraulic models to simulate flood hydrographs and generate flood inundation and hazard maps. For each scenario, Monte Carlo simulations using McBreach software produced four hydrographs corresponding to exceedance probabilities of 90%, 50%, 10%, and 1%. The results indicate that all dam breach scenarios pose a significant threat to agricultural and residential areas, leading to the destruction of numerous buildings, roads, and infrastructures. Particularly, Scenario 3, which includes PMP, was identified as the most destructive, resulting in prevailing flood hazard levels of H5 and H6 in the inundated areas. The proportion of inundated areas in these high hazard levels varied between 52.8% and 57.4%, with the number of vulnerable structures increasing from 248 to 321 for exceedance probabilities of 90% and 1%, respectively. Additionally, the number of flooded buildings ranged from 842 to 935, and 26 to 34 km of roads were found to be inundated in this scenario. These findings revealed the need for authorities to develop comprehensive evacuation plans and establish an efficient warning system to mitigate the flood risks associated with dam failure.
Water crisis across the globe has placed high pressure on social development due to the need to balance the water consumption between sustainable economy and functioning ecosystem. Integrated ...process-based modeling has been reported as an effective tool to better understand the complex mechanisms of water issues on a basin scale. Considering that it is still relatively difficult to simulate the water quantity-quality processes simultaneously, this study proposed an integrated modeling framework by coupling a hydrological model with a water quality model. Taking the Xiaoqing River Basin in the Shandong Province of northern China as an example, this study coupled a distributed hydrological model, SWAT, with a one-dimensional hydrodynamic-water quality model, HEC-RAS, to investigate its ability to simulate water quality and quality at the basin scale. The coupling of the two models adopted the “output-input” scheme, where the runoff modeling results from SWAT are input into HEC-RAS for hydrodynamic and water quality simulations of the river channel. The results show that the SWAT model can adequately reproduce runoff with accepted accuracy for the calibration and validation periods with acceptable R2 and Nash-Sutcliffe coefficients for the two hydrological stations. Further analysis also shows that the coupled model can simulate the concentration of ammonia nitrogen (NH4-N) and the chemical oxygen demand (COD) in the middle and upper stream of the river for both low and high flow periods. The coupling of the hydrological and hydraulic models in this study provides a good tool for identifying the spatial patterns of the water pollutants over the basin and, thus, helps simplify precision water management.
Integrated water quantity and quality modeling framework Display omitted
•We propose an integrated water quantity and quality modeling framework for a typical agricultural plain basin;•We coupled a hydrological model with a one-dimensional hydrodynamic water quality model for water modeling at the basin scale;•The coupled model can simulate the concentration of water pollutants well for both low and high flow periods.
This study presents the development of a vulnerability assessment methodology combining both hydraulic and oceanographic values to evaluate the fragility of the island’s coast, subject to floods. The ...study area covers the coastal part Petra - Molyvos in North-West Lesvos Island, Greece. Petra stream drains a catchment area of 8.06 km2. The flooded sections of the river’s coastal part are analyzed by the HEC-RAS model, while the coastal vulnerability index (CVI) was calculated by the InVEST model. The scenario of habitats’ role in beach protection showed 53% of coastal protection and the CVI moderate exposure to sandy beaches. A change in the geomorphology of the estuary was observed during the summer period, due to the river sediment dredging and small delta reclamation processes.
Increasing land development projects lead to demand for riverine mining, followed by erosion and deposition. The aim of the research was to assess the sedimentary impacts of mining activities on the ...Lisar River. The research material comprised environmental, hydraulic, and sedimentary information, mining history, and dimensions. Detailed topographic and TIN maps, and 55 cross-sections of the Lisar River mining, were prepared. This study simulates flow patterns in a quasi-unsteady condition and sediment transport capacity using the HEC-RAS model. The maximum change along the longitudinal profile of the river mining is 3 m. The spatial map of the mining in different river sections was determined based on the maximum allowable depth of mining. The present research recommends the Yang function use in simulations of the rivers with sandy-gravel texture accompanied with or without riverine mining and steep slope. Results indicate the current mining volume is up to three times the allowed capacity for the extraction from the Lisar River. The present research concluded that the management plan for spatial mining and measures for monitoring based on the spatial distribution of depositional and erosional sites is necessary for this and other such areas to conserve natural resources.
The Hindu-Kush-Himalaya is abode to numerous severely flood-prone mountainous stretches that distress vulnerable communities and cause massive destruction to physical entities such as hydropower ...projects. Adopting commercial flood models for replicating the dynamics of flood wave propagation over such regions is a major constraint due to the financial economics threaded to flood management. For the first instance, the present study attempts to investigate whether advanced open-source models are skillful in quantifying flood hazards and population exposure over mountainous terrains. While doing so, the performance of 1D-2D coupled HEC-RAS v6.3 (the most recent version developed by the U.S. Army Corps of Engineers) is reconnoitred for the first time in flood management literature. The most flood-prone region in Bhutan, the Chamkhar Chhu River Basin, housing large groups of communities and airports near its floodplains, is considered. HEC-RAS v6.3 setups are corroborated by comparing them with 2010 flood imagery derived from MODIS through performance metrics. The results indicate a sizable portion of the central part of the basin experiences very-high flood hazards with depth and velocities exceeding 3 m, and 1.6 m/s, respectively, during 50, 100, and 200-year return periods of floods. To affirm HEC-RAS, the flood hazards are compared with TUFLOW at 1D and 1D-2D coupled levels. The hydrological similarity within the channel is reflected at river cross-sections (NSE and KGE > 0.98), while overland inundation and hazard statistics differ, however, very less significant (<10 %). Later, flood hazards extracted from HEC-RAS are fused with the World-Pop population to estimate the degree of population exposure. The study ascertains that HEC-RAS v6.3 is an efficacious option for flood risk mapping over geographically arduous regions and can be preferred in resource-constrained environments ensuring a minimal degree of anomaly.
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•Performance of open-source flood models over mountainous terrains is investigated.•1D-2D coupled HEC-RAS v6.3 is considered for the first time to simulate flood risks.•Flood hazards from HEC-RAS and TUFLOW at 1D and 1D-2D coupled levels are analogous.•Central part of the Chamkhar Chhu basin faces very-high flood depths and velocities.•>2/3rd of the population is exposed to high and very-high flood hazards.
•A comparative study based on hydrologic and hydraulic of Jeddah watershed based on five GDEMs is presented.•The output of this study shows that the differences in watershed delineation, flood ...inundation maps, peak discharge, and runoff volume could be significant.•The GDEMs tend to overestimate or underestimate hazards when they used in flood risk applications.•The results indicate that SRTM performed better than all GDEMs in the mountain area.
Global Digital Elevation Models (GDEMs) have been increasingly used to assess the risk of flooding worldwide. However, their effectiveness and the performance of flood risk models in areas with complex terrain, such as Jeddah, Saudi Arabia, have not been comprehensively studied. This study aims to compare the performance of five distinct Global Digital Elevation Models (GDEMs) − 30-m SRTM, 30-m ASTER, 90-m MERIT, 10 m Sentinel-1 DEM, and 12.5 m ALOSPALSAR - in estimating the inundation extent and depth of the Jeddah watershed, including three dams. Both hydrological and hydraulic modeling approaches were utilized to achieve this objective. The study findings revealed that all Global Digital Elevation Models (GDEMs) produced similar watershed boundaries in the mountain area (Wadi Qaws), except for ALOS-PALSAR, which generated a different watershed boundary from previous reports and studies. However, all GDEMs failed to accurately delineate the drainage area of one of the dams, except for SRTM and ALOS-PALSAR. Moreover, ASTER and SRTM products provided the closest estimates to ground observations, producing peak discharges of 114.1 m3/s and 110 m3/s, respectively. For the entire watershed, encompassing mountain, urban, and coastal areas, GDEMs demonstrated significant differences in the watershed boundary, streams, outlet location, and peak discharge at the watershed outlet. In addition, each GDEM's flood inundation map was significantly distinct. Overall, the results suggest that SRTM outperformed all other GDEMs in the mountain area.
