HEC-RAS Software Research Articles

STUDI PEMETAAN DAERAH GENANGAN BANJIR DAS SEI KAMBING DENGAN SISTEM INFORMASI GEOGRAFIS

<p><em>Sei Sikambing River Basin is one of the Sub Das of Deli River which has an important role in water requirement in Medan City. Rainfall with high intensity is supported by changes in land use causing floods which reach 0.6 m to 1 m from river banks. The purpose of this study was to map the Sei Kambing River basin flood inundation area as information to the public in disaster mitigation efforts. The scope of this research is to analyze the maximum daily rainfall with a return period of 2 to 100 years, analyze flood discharge with a return period of 2 to 100, analyze flood water levels with HECRAS software, and spatially map flood inundation areas with GIS. The results showed that the return flood rate of the Sikambing watershed with a 25-year return period of 211.94 m<sup>3</sup>/s caused the flood level of the Sikambing watershed to be between 1.7 m to 3.7 m. The Sikambing watershed flood inundation area reached an area of 1.19 Km<sup>2</sup> which resulted in the impact of flooding on 5 sub-districts in Medan, namely Medan Selayang District, Medan Sunggal, Medan Petisah, Medan Helvetia, and West Medan.</em><em></em></p>

Hydrological hazard estimation for the municipality of Yautepec de Zaragoza, Morelos, Mexico

The hydrological hazard for the municipality of Yautepec de Zaragoza, State of Morelos, Mexico, is evaluated considering the overflow process of the rivers located in the Yautepec sub-basin. Different scenarios of hydrological hazard were generated to identify those areas with high flood potential using hydraulic modeling for three return periods (Rp) of 50, 100 and 500 years based on statistical analysis of the maximum annual discharge of the Yautepec hydrometric station. We used the Hec-Ras software and geographic information systems (GIS) to model the different flood scenarios. Our results indicate that 10% (1.5 km2) of the total urban area of the municipality will be flooded for a return period of 50 years. About 12% (1.8 km2) of the territory will be affected by flood for a Rp of 100 years. For a Rp of 500 years, approximately 13.5% (2.1 km2) of the municipality’s area will be flooded. Spatially, the central and southern regions of the municipality will be affected by flood heights greater than 1 m for Rp of 100 and 500 years. The northern zone will have heights of less than 0.50 m for Rp of 50 years. Our results can be used as a tool to prevent and reduce the impact of future floods in the municipality of Yautepec de Zaragoza.

Hydraulic assessment of flood protection measures proposal

Ensuring flood protection is a never-ending task, therefore there is always something to improve or add. Nowadays there is a big boom in detention reservoir projecting for smaller river basins in Slovakia. This paper focuses on flood protection proposal for village Vel’ká Lúka located in the central part of Slovakia. The contribution deals with the hydraulic modelling of present state of river Lukavica channel and its capacity and also proposed flood protection measures. According to geodetic survey and flow rate measurements a 5 km long partially calibrated mathematical model of the Lukavica River has been created. For this purpose, the HEC-RAS software has been used. After evaluation of the flow rate capacity through the village, a flood protection measure – detention reservoir – has been proposed using designed flood wave provided by Slovak Hydro-meteorological Institute (SHMI). According to transformation of flood wave computation, specific parameters of necessary flood protection measures were determined.

A power-law multivariable regression equation for salt intrusion length in the Bouregreg estuary, Morocco

Prediction of salt intrusion length in estuaries is a challenge for managers as well as scientists in this field. Several numerical and empirical models have been developed for the prediction of salt intrusion length in recent decades. However, all these models require large data set on estuary geometry, tide, stratification turbulence which demands experimental cost and time, and which is not always available as in our case. Thus, for reducing the complexity of analysis, a new simple equation was derived to predict the salinity intrusion length using nonlinear multivariable regression in the Bouregreg estuary, Morocco. The equation relates salt intrusion length with freshwater discharge and tidal range using a power law. The salt intrusion length predicted by the developed equation was in good agreement (R2 = 0.72) with that obtained using a numerical salinity transport model (HEC-RAS software “Hydrologic Engineering Center River Analysis System”). This simple formula is completely transparent and practical for Bouregreg estuary, allowing direct assessment of the parameters on the salt intrusion. Therefore, the proposed model can either be used to predict the salt intrusion for a given freshwater discharge and tidal range, or can used as a tool to design the minimum daily discharge to regulate the salt intrusion into the estuary, thereby providing assistance for management plans.

English

Floods are frequent and widespread phenomena with a devastating impact on the environment, infrastructures, buildings, croplands and, in the worst cases, involving animal and human lives. The paper focuses on this issue in a specific area in Italy: for this reason, at first it is illustrated a detailed analysis of the territory at the estuary of the Magra river, in the Liguria region, an area affected by this problem for a while. Then it is introduced a GIS river flood model developed with the software ArcGIS, with the support of a hydraulic model provided by the HEC-RAS software, which can be used in ArcGIS thanks to the HEC-GeoRAS component. This model is then compared to another one, provided by the University of Genova, and realized with the GRASS software, also with the support of a hydraulic model provided by the HEC-RAS package. The results show a good level of agreement. A further validation is also carried out with a comparison to the official expected flooding map provided by the Basin Authority and it shows to be quite satisfactory.

Development of an analytical benchmark solution to assess various gradually varied flow computations

ABSTRACT Accurate quantification of water-surface profile and associated length plays a prominent role in open channel hydraulics. Traditionally, hydraulic engineers consider analytical solution for a wide rectangular channel (not available in reality) or solution from seemingly more accurate numerical schemes as yardstick to assess the efficiency of their proposed approach. In this paper, a closed-form solution of gradually varied flow equation is derived for ordinary rectangular and triangular channels using Manning’s formula as the resistance equation without any approximation in the conventional governing equation. It is believed that the proposed method of integration also works for channels with vertical sidewalls such as round-corner rectangular channels. This newly developed analytical solution paves the way for numerical analysts to assess gradually varied flow computations and provides practicing hydraulic engineers with the computational speed required for obtaining water-surface profile in open channels. Five different conventional schemes – in which the gradually varied flow equation is directly integrated after some simplifications and approximations – are compared and contrasted with the analytical solution obtained in this study. Furthermore, the accuracy of three numerical integration schemes as well as the HEC-RAS software is investigated, and it is observed that simple numerical methods in which the discretization is in depth rather than distance can give almost accurate results for the gradually varied flow equation. However, for the cases where discretization in distance is required, the numerical schemes including the standard step method in HEC-RAS have errors that can be assessed and quantified via the newly developed real analytical solution.

Using Satellite Images to Analyze Technically Sukkur Barrage During Flood in Pakistan

Flood 2010 began in late July, resulting from heavy monsoon rains in Khyber Pakhtunkhwa, Punjab, Balochistan and Sindh in Pakistan. Over all Pakistan’s one-fifth area was affected by flood. According to Government data, flood directly affected about 20 million people, mostly by destruction of property, livelihood and infrastructure with a death toll of close to 2000. Indus Basin Irrigation system is one of the world's largest Irrigation system and the largest system in Pakistan. It covers Area of 17.2 Mha. Indus river basin irrigation system has three major reservoirs, sixteen barrages, two head works, two siphons across major rivers, 12 inter river link canals and 44000irrigation canal mileage. Sindh irrigation system lies below Guddu barrage, the first barrage in Sindh, enters Sindh province at a R.L. of (75m 246ft) above mean sea level. After Flood 2010, it was important to study the region of sukkur and sukkur barrage to control high flood with safe flow to avoid massive destruction. Almost one fifth portion of Pakistan was submerged in Flood water. For future planning it is important to take precautionary measures and avoid destructions at sukkur barrage. Sukkur Barrage has network based on seven canals (9923 km) 6166 miles long, feeding the largest irrigation system in the world, with more than 7.63 million acres of irrigated land which is approximately 25 percent of total canal irrigated area of the country. Structure of barrage is based on 66 spans, each 60 feet and weighing 50 tons. Here, Goal of research study is to present a hypothetical flood in Indus River at point of Sukkur barrage with potential changes in geometry of river in premises of Sukkur barrage. To measure technical analysis of sukkur barrage a computer based model is prepared through HEC RAS software. software is capable to moderate the satellite image and modify it according to contour's of area and imbedding Computer Added Design in model to analyze impact of flood 2010 at Sukkur Barrage. levees are also generated in model to overcome the problem of overtopping of flood water. Analysis shows results same as satellite images were taken during flood and impact of velocity pressure (showing water particle tracing) at gates were also measured as depositing of silt at upstream of barrage.

Hydraulic model for water management along Dâmboviţa River through Bucharest City, Romania

The main objective of the paper is to simulate the steady state flow conditions along the regulated Damboviţa River in Bucharest City. The canal has 11 reaches in series separated by control structures with gated weirs (barrages). The simulations are performed using the 1D HEC-RAS software for flows between 3 and 45 m3/s, in order to find the optimal opening of each set of gates, so that water levels along reaches are kept at the target Normal Pool Levels (NPL) elevation. For the determined operating situations optimized gate openings and gates' rating curves are drawn. The computed water surface profiles for the maximum flow allow for checking if the banks are flooded, whereas velocity values for the minimum, ecological flow of 3 m3/s highlight the reaches over which the biota could be affected during summer drought periods. This model could assist the Water Management Authority's technical staff to better operate the gates in an integrated manner. Since currently gate operations are individually performed at each control structure, such a model would be a primary step in designing and implementing an automatic controlling system for the entire Damboviţa canal in Bucharest City.

ANALISA PROFIL MUKA AIR BANJIR SUNGAI KRUENG PASE KABUPATEN ACEH UTARA

Excess water capacity in river areas will cause flood hazards that mostly occur in downstream areas that are flood areas at high risk as a result of natural processes and the effects of human actions. In the case of floods, water runoff undermines the embankments and drowns agricultural / settlement areas upstream, and is aggravated by considerable sedimentation. Based on the existing problems, the analysis of the discharge and the water level (water profile) becomes very important to get a precise picture of locations prone to the overflow of the river Kr. This pase. Discharge and water profile analysis using HEC RAS software for various return periods. From the results of the research is expected to get a clear picture of the location that is vulnerable to overflow so that in handling the river will be on target. Based on the calculation using HEC RAS software, at point P 581 the water level condition at 2.3 years discharge the difference of the height of the embankment and the water level is 50 cm to 60 cm, while in the discharge condition 25 years the elevation of the face almost passes through the dike's height with a selisish of about 10 -15 cm. This condition is an unsafe category because for rivers whose debit is greater than 15 m3/s the minimum wavelength is 1.00 m. So that with good conditions at 2.3 years discharge and 25 years of discharge is very potential to occur overflow.Keywords: discharge, waterlevel, flood

Study of Flood and Coastal Flood Control in Madukoro Area, Semarang City, Indonesia

Madukoro area located on the northern coast of Semarang City has been prone to flooding caused by rainfall and seawater high-tide. Ineffective flood control management and land subsidence are considered as the cause of this problem. In order to understand land subsidence effect and flood control performance, location, water surface height of the inundation in West Flood Canal, western part of Madukoro area need to analyze. Flood analysis was conducted using HEC-HMS software and rational method. Flow hydraulics on five channels, i.e. the West Flood Canal, Ronggolawe River, Karangayu River, Arterial Channel and Madukoro were analyzed using HEC-RAS software. Increasing levee level and additional water pumps in Madukoro and Ronggolawe were chosen as flood control alternatives. Its performance was investigated through software simulation. The results showed total runoff volume in all drainage channels for 2-years return period discharge was about 80% of capacity with 0.7 m water depth. Runoff volume in West Flood Canal with 50-years return period discharge was about 40%. Land subsidence 4 cm/year affected the water level increase on West Flood Canal. Operation of 2 - 4 pump units could not significantly decrease water level at flood peak, yet increase flood recession time 6 - 8 hours.

Flood Modelling and Analyzing of Attanagalu Oya River Basin Using Geographic Information System

GIS (Geographic Information Systems) are used to store and process terrain data. Using GIS for could be very effective in flood modelling as it becomes very accurate with the use of the Digital Elevation Models. These DEMs could be analyzed with various tools in GIS software and by processing these terrain models, data necessary for the development of flow and flood models can be extracted with a minimum effort in the field. In this research Attanagalu Oya river basin was selected due to its constant exposure to floods and the model for Attanagalu Oya would be processed and the data extracted would be exported in to Hec-Hms and Hec-Ras software to model the flow and create a flood simulation to determine the extent of the flood. By using future rainfall forecasts in the flood simulation developed in this research future floods can be forecasted with great accuracy. As this model could be used to forecast the future floods and their extent it makes this model a warning system for future floods and could be used to mitigate the property loss and the damage incurred. Keywords

The influence of weight coefficients in the Preissman scheme on flows in the lower Odra river network using the Hec-Ras software

Mathematical modelling of water flows processes in rivers and open channels for many years has been target of researches for hydrotechnics and hydrologists. For flows forecasting in open channels models based on one-dimensional equations are mostly used. This models are assuming that the main flow component is parallel to the channel axis is substantially larger than others, so it can ignore them. One of the most effective methods for solving de Saint-Venant equations is the finite difference method with using four-point Preissman Scheme. In this paper an analysis of the impact of Preissman weighting parameters on flows in the lower Odra river network.

Modélisation hydraulique du système Sebou-Fouarat, ville de Kenitra, Maroc - Cas des inondations de 2010

The city of Kenitra, located in the extreme downstream of the Sebou basin, is threatened by floods caused by the overflowing of the Oued Sebou and the rise of Oued Fouarat. The hydraulic modeling study of the Sebou Fouarat system in transient mode is carried out by the HEC-RAS software and has implicated the two rivers. Two geometric models were constructed on the basis of a digital terrain model (DTM) using the Arc-GIS and HECGeoRAS softwares after processing the collected topographic data. The first model, of which the areas of Merja Fouarat and Al Assam have been represented by cross-section, is one-dimensional. The second one is also onedimensional in which the two areas of Merja Fouarat and Al Assam are introduced as water storage zones. The components of these models are the stream sections, lateral links, storage areas and junctions between the branches of each model. The flood hydrographs of the Sebou and Fouarat rivers are introduced as conditions at the upstream limits of the models while the tidal is introduced as a downstream condition. After the stability and calibration of the models, the results of the consulted hydraulic simulations are the variations of the water levels as well as the temporal variations of the flow rates for each section, the maximum flow velocities and the propagation times of the flood waves. The analysis and comparisons of these results strongly suggest using the second model for the treatment of the flood issues as a decision-making tool helping to manage floods during times of crisis.

Respuesta hidrológica al cambio climático en regiones áridas: caso de estudio en los Comondú, Baja California Sur, México

Background. Currently, climate change is one of the most relevant phenomena within the scientific environment; this change has been recorded as an increase in temperatures on a global scale. For the central zone of Baja California Sur (BCS), Mexico, climate models also indicate an increase in the frequency of extreme precipitation. The study area covers two towns (San Jose and San Miguel de Comondu) whose urban and rural areas are located in a ravine of approximately 16 km in length and up to 800 m in width. Goals. To carry out a historical, statistical analysis of the climatic variability and model the response of the Comondu stream to extreme precipitation events. Methods. Climatic variability was analyzed with databases from the Comondu weather station, operated by the National Meteorological Service (SMN). In addition, the runoff pattern in the Comondu stream was ascertained in the event of extreme precipitation events, similar to or close to events with a return time of 1000 years, using hydrological and hydraulic models of HEC-1 and HEC-RAS software. Results. In the case of Los Comondu, BCS, there is a clear upward trend in the 24-hour extreme precipitation data, which implies that the danger of flooding in populated areas and crops increases considerably. The occurrence of a 1000-year event would affect about 86,864 m2 of the urban area of both towns and 201,570 m2 of the area under cultivation. Conclusions. The results of our modeling indicate an increase in area, depth, and speed of the stream, increasing the risk of flooding in the lower areas of Los Comondu, BCS. Based on our modeling’s results, measures should be promoted to safeguard the population and the economy of Los Comondu.

Peak flood estimation under overtopping and piping conditions at Vahdat Dam, Kurdistan Iran

Estimation of maximum discharge and time of transfer dam break wave are among the main factors in provision of emergency action plan and safety assessment of dams. Most dam breaks begin with a breach in the body of the dam or flood overtopping. Estimation of maximum discharge for determining affected areas and also determination of hazards due to the dam break are essential issues. In this research, the dam break of Vahdat Dam located in Kurdistan, Iran, and in neighborhood of Sanandaj City was simulated by integrating ArcMap and HEC-RAS software and field observations. The necessary data was collected from the corresponding organizations. The Manning coefficient of the Gheshlagh River at downstream of the dam was estimated using the Manning coefficient relationships and field observations and measurements. The breach dimensions were determined using the conventional empirical relationships. The dam breaks in both overtopping and piping states were simulated. The maximum discharge values obtained from the modeling and empirical relationships were compared. The results indicated the substantial effect of selecting break types on the hydraulic characteristics of dam break wave in the river and downstream areas. While in the case of break due to the breach, selection of the methods for calculation of breach dimensions would affect the break and these relationships in various conditions would give different breach dimensions.

Water Quality of Surface Runoff in Loop Two Catchment Area in UKM

For a country that is developing, there is a need to control and maintain the quality of raw water, with adequate quantities to ensure continuous supply of clean water. In Malaysia, urban development activities especially constructions, is believed to be one of the activities that contributes to the deterioration of the quality of surface runoff. The main objectives of this project are to investigate water quality of surface water runoff at UKM’s loop two catchment areas and to observe the effect of slope failure, erosion, and construction activities on surface water quality in UKM Bangi campus. Besides that, the development of hydraulic models using HEC-RAS software is also the objective of this research. This research is conducted through field study and laboratory works. The main findings confirmed that water quality and total surface runoff in the catchment is directly affected by slope failure, erosion, and construction activities. Results from HEC-RAS modeling revealed that the drains surrounding the lake are not overflowing or flooding.

Sediment transport modelling in wadi Chemora during flood flow events

AbstractThe sediment transport is a complex phenomenon by its intermittent nature, randomness and by its spatiotemporal discontinuity. By reason of its scale, it constitutes a major constraint for development; it decreases storage capacity of dams and degrades state of ancillary structures.The study consists in modelling the transport of sediments by HEC-RAS software in wadi Chemora (Batna, Algeria). In order to do this, we have used hydrometric data (liquid flows, and solid flows) recorded at level of the four hydrometric stations existing in watershed of wadi Chemora, the MNT of the wadi and lithologic characteristics of the wadi.In the analyses of results we used the parameters from two different floods (the first one involved the whole watershed and the second – a part of the basin) along of system of wadi Chemora (wadi Chemora and its tributaries): sediment transport capacity, volume of sediments delivered to and leaving the system and areas sensitive to erosion and sedimentation.

Environmental impact of RO units installation in main water treatment plants of Basrah city/south of Iraq

The citizens of Basrah city are suffering from the problem of high salinity water supply. This problem is proposed to be solved by installing RO units in 16 water treatment plants of Basrah city. RO units produce high-salinity brine water. The aim of this study is to predict the environmental impact of RO units installation measured in terms of TDS increase of Shatt Al-Arab River water. The TDS increase was predicted using HEC-RAS software. The software was applied to simulate twelve cases of TDS distribution in water of Shatt Al-Arab River. During each of the twelve simulation cases, the proposed RO units were assumed to have recovery percent (RP) of 50% and 85%. The simulation results indicated that when the proposed RO units have RP of 85%, the max percentage of TDS increase is 5.9%. While, when the proposed RO units have RP of 50%, the max percentage of TDS is 2.7%. The comparison of these results with the regulation criteria of brine water discharge shows that; when the installed RO units have RP of 85%, the percentages of TDS increase will exceed the salinity limit of most regulation criteria (5%).

Analytical and numerical study of the salinity intrusion in the Sebou river estuary (Morocco) – effect of the “Super Blood Moon” (total lunar eclipse) of 2015

Abstract. The longitudinal variation of salinity and the maximum salinity intrusion length in an alluvial estuary are important environmental concerns for policy makers and managers since they influence water quality, water utilization and agricultural development in estuarine environments and the potential use of water resources in general. The supermoon total lunar eclipse is a rare event. According to NASA, they have only occurred 5 times in the 1900s – in 1910, 1928, 1946, 1964 and 1982. After the 28 September 2015 total lunar eclipse, a Super Blood Moon eclipse will not recur before 8 October 2033. In this paper, for the first time, the impact of the combination of a supermoon and a total lunar eclipse on the salinity intrusion along an estuary is studied. The 28 September 2015 supermoon total lunar eclipse is the focus of this study and the Sebou river estuary (Morocco) is used as an application area. The Sebou estuary is an area with high agricultural potential, is becoming one of the most important industrial zones in Morocco and it is experiencing a salt intrusion problem. Hydrodynamic equations for tidal wave propagation coupled with the Savenije theory and a numerical salinity transport model (HEC-RAS software "Hydrologic Engineering Center River Analysis System") are applied to study the impact of the supermoon total lunar eclipse on the salinity intrusion. Intensive salinity measurements during this extreme event were recorded along the Sebou estuary. Measurements showed a modification of the shape of axial salinity profiles and a notable water elevation rise, compared with normal situations. The two optimization parameters (Van der Burgh's and dispersion coefficients) of the analytical model are estimated based on the Levenberg–Marquardt's algorithm (i.e., solving nonlinear least-squares problems). The salinity transport model was calibrated and validated using field data. The results show that the two models described very well the salt intrusion during the supermoon total lunar eclipse day. A good fit between computed salinity and measurements is obtained, as verified by statistical performance tests. These two models can give a rapid assessment of salinity distribution and consequently help to ensure the safety of the water supply, even during such infrequent astronomical phenomenon.

Perbandingan Hasil Pemodelan Aliran Satu Dimensi Unsteady Flow dan Steady Flow pada Banjir Kota

One dimensional flow is often used as a flood simulation for the planning capacity of the river. Flood is a type of unsteady non-uniform flow, that can be simulated using HEC-RAS. HEC-RAS software is often used for flood modeling with a one-dimensional flow method. Unsteady flow modeling results in HEC-RAS sometimes refer to error and warning due to unstable analysis program. The stability program among others influenced bend in the river flow, the steep slope of the river bottom, and changes in cross-section shape. Because the flood handling required maximum discharge and maximum flood water level, then a steady flow is often used as an alternative to simulate the flood flow. This study aimed to determine the advantages and disadvantages of modeling unsteady non-uniform and steady non-uniform flow. The research location in the Kanal Banjir Barat, in the Semarang City. Hydraulics modeling uses HEC-RAS 4.1 and for discharge the plan is obtained from the HEC-HMS 3.5. Results of the comparison modeling hydraulics the modeling of steady non-uniform flow has a tendency water level is higher and modeling of unsteady non-uniform flow takes longer to analyze. Results of the comparison the average flood water level maximun is less than 15% (± 0,3 meters), that is 0.27 meters (13.16%) for Q50, 0.25 meters (11.56%) for Q100, dan 0.16 meters (4.73%) for Q200. So the modeling steady non-uniform flow can still be used as a companion version the modeling unsteady non-uniform flow.