HEC-RAS Model Research Articles

The Utilization of Satellite Data and Machine Learning for Predicting the Inundation Height in the Majalaya Watershed

The Majalaya area is one of the most valuable economic districts in the south of Greater Bandung, West Java, Indonesia, and experiences at least six floods per year. The floods are characterized by a sudden rise in the water level approximately one to two hours after the rain occurs. With the aim of reducing flood risk, this study models a data-driven method for predicting the inundation height across the Majalaya Watershed. The flood inundation maps of selected events were modeled using the HEC-RAS 2D numerical model. Extracted data from the HEC-RAS model, GSMaP satellite rainfall data, elevation, and other spatial data were combined to build an artificial neural network (ANN) model. The trained model targets inundation height, while the spatiotemporal data serve as the explanatory variables. The results from the trained ANN model provided very good R2 (0.9537), NSE (0.9292), and RMSE (0.3701) validation performances. The ANN model was tested with a new dataset to demonstrate the capability of predicting flood inundation height with unseen data. Such a data-driven approach is a promising tool to be developed to reduce flood risks in the Majalaya Watershed and other flood-prone locations.

The effects of check dams on the amount and pattern of flood

In this study, field measurement, spatial information, and HEC-RAS modeling were used to determine changes in the amount and pattern of flow in a waterway due to the construction of check dams. The research was conducted in Khorkhoreh watershed, Kurdistan province, Iran. The location map of the structures and their upstream area was prepared in the GIS environment. The flow rate with different return periods was calculated from empirical methods. To simulate the changes in the flow pattern, the HEC-RAS model was calibrated. Flows and corresponding water levels were measured. The flow pattern and time was quantitatively calculated and compared with the conditions before construction. The results by HEC-RAS showed that in most structures, the flow velocity increased after passing the structures. In a 2-yr flood, the flow time increased by 82.8 minutes due to the check dams. This time is lower in floods with higher return periods.

Assessment of the combined effects of Manning roughness and DEM resolution for the water surface elevation prediction using the HEC-RAS model: a case study of Moudjar River in the Northeast of Algeria

Assessment of the combined effects of Manning roughness and DEM resolution for the water surface elevation prediction using the HEC-RAS model: a case study of Moudjar River in the Northeast of Algeria

The area of flood run-off with HEC-RAS modeling in Cabang Dua River, Manokwari Regency, West Papua Province

Wosi watershed is one of the watersheds with a Classification Restored Carrying capacity, and it is also indicated to have decreased hydrological function. this study aims to find out the extent of the flood discharge plan/peak runoff (m3/s) and plan/peak of the flood affected (ha). This research was conducted in 3 months (September - November 2020). The observed object is Cabang Dua river Wosi, in Manokwari, West Papua. The data of the research results are analyzed descriptively quantitatively with the technique of interpretation and analysis of maps. The results showed the value of flood discharge plan on repeat 2, 5, 10, 25, 50, 100 years respectively are 89.05 m3/s, 118.50 m3/s, 128.46 m3/s, 135.01 m3/s, 137.57 m3/s, and 138.94 m3/s. It is known that Cabang Dua river is unable to accommodate the discharge and causes flooding at any time (2-100 years) with successive areas of 13.88 ha, 14.36 ha, 14.52 ha, 14.60 ha, 14.67 ha, and 14.71 ha.

Simulating the Flood Limits of Urban Rivers Embedded in the Populated City of Santa Clara, Cuba

Floods are a natural phenomenon that cause damage to structures and property as well as negatively affect human life. Assessing the extent, speed, power, and depth of flooding has always been a challenge for water resource planners. This research developed a hydraulic simulation model for the Cubanicay and Bélico urban rivers embedded in the city of Santa Clara, Cuba. The methodology was based on a one-dimensional model of the Hydrological Engineering River Analysis System (HEC-RAS) and GIS-based methods. The HEC-RAS model (Beta) and three modeling flood tests for scenarios of 1% (100 years), 2% (50 years), and 10% (10 years) of probability for hydrometeorological events were analyzed. Bank lines, flow path lines, and cross-section cut lines were extracted from Digital Elevation Models. Manning’s roughness coefficients were considered for the channel morphology and soil typology. The flood Beta model results were accurate with a difference of ±0.10 m considering the water footprint found in the field. The results showed that the areas near the control section 2 + 87 presented a high risk of flooding. The flood limit map for urban areas could be an important tool for researchers, planners, and local governments for risk assessment and to develop evacuation plans and flood mitigation strategies in order to reduce human and economic losses during a flood.

Improving quantitative and qualitative equity of water distribution systems

In most of the main canals in Egypt, such as the Mit Yazid canal, the tail end regions have a high dependence on agricultural drainage water. The current study aims to improve the situation in tail regions by mixing the drainage water with the surface water at head reaches while maintaining environmental standards. Simulations and water quality models (HEC-RAS model) were used to validate the proposed solutions. The study investigated two scenarios to lift 10.50 and 12.0 m3/s of drainage water at the head reach. The results showed that it is possible to considerably increase the flow to downstream areas while maintaining water quality standards. The study is important as municipal water and its effluent is increasing while irrigation water is decreasing, and therefore, the dependence of tail end farmers on polluted drainage water will increase. The situation in these regions will be unsustainable unless the burden is distributed between the head and tail regions.

Hydraulic analysis of flash flood events using UAV based topographic data and citizen science in Enkare Narok river basin

The purpose of hydraulic analysis of floods is to improve our understanding of flood behavior and to develop strategies for managing and mitigating flood risk within a floodplain. This study aimed to conduct a hydraulic analysis of a flash flood event in Narok, Kenya, using topographic data collected by an unmanned aerial vehicle (UAV). The channels in the town were dry, making it an ideal opportunity to use UAV to map the channel and floodplain and generate topographical variables for hydraulic modeling. Detailed flight plans were created to cover the built-up area of the town, and the topography was reconstructed from the UAV survey data to generate a 5 cm Orthomosaic and a 5 cm Digital Surface Model (DSM). These topographic datasets were used to extract all the necessary geometric data, including a channel centerline, bank lines, channel cross-sections, blocked flow areas, details about the bridges and land use and land cover (LULC) of the floodplain. HEC-RAS model was used to simulate the flow through the channels during the flood event on November 27, 2019. The inundation depths reached 4 m at their highest point and extended up to 290 m from the channel at their furthest point. The model results were validated using survey data of observed wrack marks and photographs taken by local non-experts. This study demonstrates the potential of UAVs to improve flood simulations by providing accurate and detailed data collection at a lower cost and with fewer resources. In addition, the usefulness of the UAV-derived data is demonstrated beyond extracting river cross-sections, which previous related studies were limited to. Integrating UAVs into flood management strategies has the potential to lead to more effective and efficient flood management in the face of increased risk of flooding.

Assessing the Implication of Climate Change to Forecast Future Flood Using SWAT and HEC-RAS Model under CMIP5 Climate Projection in Upper Nan Watershed, Thailand

Climate change will affect Southeast Asian countries, particularly Thailand. There are still insufficient studies on rainfall, streamflow, and future floods in the Upper Nan Watershed, northern Thailand. This study examined how future climate change will affect the rainfall, streamflow, and flooding in the Upper Nan Watershed. SWAT and HEC-RAS models were utilized to assess the future streamflow and flooding in this area. The models used data from 1980–2020, which were taken from seven Upper Nan meteorological stations and two discharge stations. In this study, the impact of future climate change was predicted using three GCMs, under RCP4.5 and RCP8.5 scenarios. The historical data analyzed in this study indicated that rainfall in the study area has a positive trend. Climate change will increase further, from 18% to 19%, which will cause more fluctuations and lead to wetter conditions, both in the wet and dry seasons. Climate change delayed the hydrograph peak and the SWAT-modelled streamflow in the N1 and N64 stations by between 0.3% and 5.1%. RCP8.5 inundated all of the stations more than RCP4.5. Our models showed that in the medium future (2041–2060), the inundated area will be similar to that during the 100-year flood probability. Thus, monitoring and preparation are necessary to avoid repeating the considerable 2011 flood losses in Thailand.

Flood inundation mapping of upper Krishna basin using hydrodynamic model

Floodplain management and mapping are new and applied methods in river engineering and for the prediction of flood hazards. Krishna river basin is the second largest river basin in Peninsular India. This basin is one of the flood prone basins in India. The purpose of this study is to focus on the analysis of HEC-RAS to assess and predict the flood depth and spatial extent of flood in the upper Krishna River basin which is drained by Krishna River. To determine extent of inundation, the hydrodynamic model HEC-RAS with ArcGIS was used. For this, discharge data of two months from August and September 2012 has been processed in the study. A methodology was applied to combine hydraulic simulation model, HEC-RAS and GIS analysis for delineation of flood extents and depths for upper Krishna basin in India. Results obtained by using HEC-RAS Model were used by integrating with Arc-GIS to floodplain maps. Through this floodplain maps, the areas that are vulnerable to hazards, have been identified. The results of this research will benefit in future of flood forecasts on a regional scale, also they will be beneficial for water resources management and planning.

ANALISIS DEBIT BANJIR RANCANGAN UNTUK NORMALISASI SALURAN DRAINASE DAN DESAIN DINDING PENAHAN TANAH DI DAERAH SEKITAR SUNGAI EPHEMERAL

Rehabilitation of buildings around the area around the river is considered by the owner of the activity because during high rainfall it will cause flooding. Flooding will result in delays in the building rehabilitation process because river water overflows into the activity location. One of the areas around a river in Bali, namely Tukad Bangin located in Pecatu Badung, is an ephemeral river, namely a river whose water only exists during the rainy season and often floods due to abnormal drainage channels and the absence of retaining walls. In the environment around Tukad Bangin there are buildings which during the rainy season cause frequent flooding, so a plan for building rehabilitation is carried out by making drainage channels and senders, then the results of calculating the design flood discharge in the Tukad Bangin Pecatu Badung area are carried out. The method used in this study is a quantitative method, namely measuring from direct observation at Tukad Bangin and then calculating the design flood discharge for various return periods for planning the design of drainage channels and shores. The results of the design flood discharge analysis with Q1 year are 15.47 m3/sec, Q2 year is 49.74 m3/sec and Q5 year is 65.89 m3/sec. From the simulation results of the water surface profile, the extreme depth values for discharge at 2-year return period are 1.54 m, 5-year return periods are 1.80 m, 10-year return periods are 1.93 m, 25-year return periods are 2.06 m and a 50-year return period of 2.04 m, so that with the HEC-RAS modeling it can control the height of the flood protection embankment and the design of the planned drainage channels and canals can be carried out.

Roughness Coefficient in Euphrates River Reach between Haditha Dam to Ramadi Barrage

Accurate computation of the roughness coefficient is important in the studies of open channel flow. To measure and identify the hydraulic characteristics of the flow system, the model simulation is necessary to study and get the results of the hydraulic properties to specify Manning coefficient of the Euphrates River. In this study, the reach is extended along the Euphrates River from Haditha Dam to Ramadi Barrage with a distance of 169km. The HEC-RAS model was implemented to simulate the flow within the study reach. The geometry of the river was represented by more than two hundred cross-sections surveyed in 2013 and 2021. The model was calibrated using some observed discharges at the Heet gage station for records of the last five years. The Model was validated using five sets of observed water levels in different cases of manning coefficient in the model. The Root Mean Square Error (RMSE) was used for comparison of the model results. Results of the model showed that the roughness coefficient value for this reach is 0.026 for the river bed and 0.030 for the River bank. These values gave the best coincidence between the simulated and observed values of water levels.

Investigating effects of mining on sedimentary properties of Lisar River (Guilan Province, Iran) using HEC_RAS model

ABSTRACT 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.

Ecogeomorphological condition and hydrological indicators of the self-purification capacity of rivers: A case study of Siminehrood River in Northwestern Iran

Aims: The steady development of human communities and the spread of industrial activities are major contributors to environmental pollution, especially the contamination of water resources. Population growth and thus the acceleration of municipal, industrial, and agricultural wastewater release have adversely affected these inestimable resources and restricted their accessibility. This work attempts to identify the ecogeomorphological condition of rivers in drainage basins emphasizing the Siminehrood River in Northwestern Iran. The purpose is to study all nonpoint source (PS) and PS pollutions and circumstances that weaken and intensify the pollution rate and self-purification capacity of rivers, especially in the Siminehrood River. Materials and Methods: All data and statistics were collected and their seasonal average was calculated. Maps and variables associated with the physical properties of drainage basins were then extracted through ArcGIS. The Schuler diagram was plotted through Chemistry software for all stations and each season to assess the type and chemical quality of the river's drinking water. HEC-RAS model, HEC-GEORAS extension, and ArcGIS were employed for simulation of river flow and calculation and determination of water surface profiles and other hydraulic characteristics of flow including water depth, water flow rate, stream shear stress, and stream power. Results: According to the analyses and results, the improper ecogeomorphological condition of rivers and their low self-purification capacity are directly correlated with the mean river water depth, water flow rate, slope of the river basin, and environmental differences. Conclusions: Within the study area, the highest environmental instability and the least self-purification capacity were observed downstream of the sub-basin in which the mean and maximum depth of water were, respectively, 3.10 m and 8.803 m. Insignificant water flow rate (0.86 m/s on average) and slope of <4% in the area have stagnated water flow in most areas and consequently declined the content of dissolved oxygen and the quality of water. Conclusively, this sub-basin can be reported as a region with an improper ecogeomorphological condition.

Flood Modelling Using Integration of Multi-data Analysis and HEC-RAS Model in Mata Allo River, Sulawesi

The amount of rainfall in a watershed with steep slopes, small cross-sectional areas, and less water catchment areas. This will cause an increase in water discharge in the river which can cause flooding. These characteristics can be found in Mata Allo River, Enrekang Regency. To identify the most flood-hit areas, the simulating model can be done utilizing the HEC-RAS program. Use of Satellite Imagery Data such as Sentinel-2 for extracting land use data information, and Sentinel-1 for data extraction of actual water bodies/rivers. The analysis is carried out by integrating the interpretation results from multi-sensor images with the results of modeling the flood inundation area using HEC-RAS. Based on the analysis results, the land use classification accuracy is 82.9% for Sentinel-2 data using the random forest algorithm. While for the actual extraction of water bodies using Sentinel-1 imagery was 89.6%. Approaching the threshold value between water and non-water bodies is taken using -13.39. The inundation area in the study area reached 87.66ha at the largest discharge model. The most affected land use after integrating each data is built-up land, most of which are settlements covering an area of 47.26ha.

Alternatives of drainage engineering in tidal flood prone areas using eco-infrastructure approach in North Pekalongan

Tidal flood is one of the the most persistent disaster in Indonesia. It often occurs during the high tide, which can be exacerbated by extreme tidal surges, land subsidence, and sea level rise. The coastal area of Pekalongan, especially in Panjang Wetan, is one of the impacted areas during the extreme tidal flood in May 2022. Data from Indonesia Geospatial Agency showed that maximum spring tides elevation reached + 0.4 to +0.5 m above the mean sea level. Currently, although sea dike has been installed in some parts, floods are still occurring. On the other hand, interest on the nature-based solution concept is globally increasing. Therefore, this study aimed to explore the possibility of eco-infrastructure applications in mitigating coastal flooding. The analysis was done through numerical simulation using HEC-RAS model which divided into three different scenarios: existing condition, grey infrastructure scenario, and a combination of grey and blue infrastructure scenario. The simulation results indicated that the existing drainage conditions in the area was not sufficient to accommodate the flood. The grey infrastructure could restrain the tidal overtopping, while the proposed eco-infrastructure could address this issue mainly by providing a buffer zone to prevent the water from entering the settlement areas.

Quantifying the evolution of ensemble water temperature forecasts as a function of weather forecast lead-time: case study on the Nechako River watershed

Producing and improving hydrological and hydrodynamic forecasts while accounting for uncertainty through a probabilistic approach is useful in various applications, such as for water temperature forecasting. To produce such ensembles, probabilistic meteorological forecasts can be fed into hydrological and water temperature models for different lead-times. This study aims to gauge the impact of the meteorological forecast quality on the accuracy and reliability of water temperature forecast ensembles generated through the HEC-RAS process-based hydrothermal model. The Nechako River, a managed river system in British Columbia, Canada, is used in this case study. The thermal forecasts were generated and evaluated from 2017 to 2020. The tested hypothesis is that improvements in the meteorological forecasts would result in reducing the uncertainty and improving the accuracy of the water temperature forecast ensembles at various lead-times. The results of this study show that the thermal forecasts were indeed improved in terms of their sharpness and their individual accuracy, but no significant impacts were noted over the accuracy of the ensembles. Reliability was also investigated, and it was revealed that water temperature forecast ensembles were initially under-dispersed over the Nechako River, and that this issue was exacerbated when the HEC-RAS model was forced with better quality ensemble weather forecasts. The presence of lakes along the river and the meteorological forecast’s reliability are considered and discussed as causes for this issue. Overall, it was concluded that a reduction of the meteorological inputs’ uncertainty did not improve the uncertainty representation of water temperature forecasts for this system.

Flood Modelling Studies Using River Analysis System (HEC-RAS) For Flood Plain Area in Muar City

Floods are the most frequent type of natural disaster and occur when heavy precipitation for days or even weeks. Floods will cause extensive destruction, resulting in loss of life and disruption to personal property and vital infrastructure for public health. In this study, HEC-RAS model was used to identify the flood prone area and to determine cross section at floodplain area along the stream network. The study was conducted in the area Muar, Johor. The methodology involved collection of parameters such as length of stream, lateral &amp; elevation of coordinates, streamline and flow data to perform a hydraulic simulation. Different value of flowrate had been used by using the manning equation to estimate the drainage or channel capability to manage the flowrate. The number of station for each cross section need to locate in order to simulate the cross section along the river or channel. Meanwhile, the result outcome will show the cross section for each station. From the result, the analysis of the cross sectioninclude with the affected area of floodplain was identified. According to the hydraulic model generated by HEC-RAS software, 7 of 20 stations found will be flood for the 10 years return period since they were unable to accommodate the water flow. By doingthis research, the flood model will be developed and HEC-RAS software is one of the tool that can analyse and model for the floodplain area. In a meantime, the government can control and give an early warning about the flood incident.

Potential of Two SAR-Based Flood Mapping Approaches in Supporting an Integrated 1D/2D HEC-RAS Model

This study investigates the potential of Sentinel-1 data in assisting flood modeling procedures. Two different synthetic aperture radar (SAR) processing methodologies, one simplified based on single-flood image thresholding and one automatic based on SAR statistical temporal analysis, were exploited to delineate the flooding caused by a storm event that took place in Spercheios River, Central Greece. The storm event was simulated by coupling a HEC-HMS hydrologic model and an integrated 1D/2D HEC-RAS hydraulic model. Both SAR methodologies were compared to each other and also used as a reference to test the sensitivity of the hydraulic model in the variation of upstream discharge and roughness coefficient. Model sensitivity was investigated with respect to the change in the derived inundation extent and three additional metrics: the Critical Success Index (CSI), the Hit Rate (HR), and the False Alarm Ratio (FAR). The model response was found to be affected in the following order: by the upstream inflow, and by the variation of the roughness coefficient in the main channel and in the land use “cultivated crops”. The discrepancies observed between model- and SAR-derived inundation products are associated with the uncertainty accompanying the SAR processing and the utilized satellite data itself, the underlying topography, and the structural uncertainty inherent in the modeling procedure. Regarding the SAR methodologies tested, the second one (FLOMPY approach) proved to be more suitable, yielding a more coherent and realistic flooded area. According to the applied metrics and considering as reference the FLOMPY result, model performance ranged between 22–27.5% (CSI), 36.9–60.4% (HR), and 62.1–68.2% (FAR).

Flood Analysis Using HEC-RAS and HEC-HMS: A Case Study of Khazir River (Middle East—Northern Iraq)

Floods frequently threaten villages near the Khazir River’s floodplains, causing crop losses and threatening residential areas. We used flood-related hydrological software, including WMS and HEC-HMS, to study this issue and determine how to reduce the recurrence of flooding. The software can be used to calculate a hydrograph of torrential flows in a river drainage basin and estimate the volume of torrential water and its flow rates on the Earth’s surface. The depth of rain has been evaluated and calculated in the SCS Unit Hydrograph for different return periods of 2, 5, 10, 20, 50, and 100 years. According to our study’s findings, the volume of the river’s drainage basin floods ranged between 29,680 and 2,229,200 m3, and the maximum flow value ranged between 10.4 and 66.4 m3/sec during various reference periods. To analyze and model the flood risks of the Khazir River, the HEC-RAS model was combined with the HEC-GeoRAS extension in ArcGIS. The floods were the focus of two study periods, 2013 and 2018, and were based on the digital elevation model and river discharge during the floods. According to the classification map of the flood depths, the areas of flood risk varied from low to very low (80.31%), medium (16.03%), and high to very high (3.8%). The analysis of the results revealed that the villages closest to the river’s mouth were more affected by the floods than other villages further downstream. HEC-HMS and HEC-RAS have been shown to have a strong correlation in evaluating flood risks and reliably forecasting future floods in the study area.

Multiscenario flood hazard assessment using probabilistic runoff hydrograph estimation and 2D hydrodynamic modelling

In this paper, we aim to define a procedure of flood hazard assessment applicable to large river basins in which flood events can be induced/sustained by the full basin area or by fractions of the total area as functions of the extent of the triggering precipitation event. The proposed procedure is based on a combined approach accounting for (1) the reconstruction of intensity–duration–frequency curves expressing the magnitude in terms of intensity for multiple return periods; (2) the application of the soil conservation service method for runoff estimation from a selected rainfall scenario considering some characteristics of the basin (i.e. soil type, land use/treatment, surface condition, and antecedent moisture conditions); (3) 2D hydrodynamic modelling conducted by the HEC-RAS model using runoff hydrographs as hydrological input data; (4) the reconstruction of flood hazard maps by overlaying multiple inundation maps depicting flood extent for different return periods. To account for the variability in the extent of the triggering precipitation event and the resulting input hydrograph, multiple contributing areas are considered. The procedure is tested at the archaeological site of Sybaris in southern Italy, which is periodically involved in flood events of variable magnitude. The obtained results highlight that the variable extent of the floodable area is strongly conditioned by the extent of the contributing area and return period, as expected. The archaeological site is always involved in the simulated flooding process, except for the smallest contributing area for which only a 300-year event involves this part of the site. Our findings may be useful for developing and supporting flood risk management plans in the area. The developed procedure might be easily exported and tested in other fluvial contexts in which evaluations of multiple flood hazard scenarios, due to the basin geometry and extent, are needed.