HEC-RAS

Rivers are easily accessible resources of water for miscellaneous uses
but the erosion and sedimentation inrivers are unique and great deal of
importance. The analysis of flow and sediment in riverunder different
conditions is a base for rivers’ behavior and decision making on
engineering aspects. Kunar River is an important river of Afghanistan,
has considerable interest because of strategic and environmental
condition regarding water resources project planning, agriculture,
forests, hydropower and industrial scope. This study is carried out to
simulate the process of erosion and sedimentation using HEC-RAS
model to assess hydraulic parameters and sedimentation processesin
250 Km stretch of Kunar Riverfrom Nari district of Kunar province to
Pul-e-Kama of Nangarhar Province. The model was calibrated
manually for hydraulic parameters of river flow and then sediment
transport model was simulated. The changes in transverse and
longitudinal profile, velocity and shear stress variation along the river,
mass inflow and outflow, bed level change of river and suspended
sediment concentration is studied for the modeled length.The sediment
transport from river tributaries and gullies joining the river from two
sides of narrow valley isalso assessed.

Akarsular, evsel tüketim, tarımsal sulama ve endüstri için gerekli olan suyun karşılanmasında, ayrıca uygun taşıma yolları, sürdürülebilir enerji ihtiyacı ve tüm canlıların doğal yaşamları için vazgeçilmez en önemli su kaynaklarından birisidir. Akarsulardan sadece yararlanmak için değil aynı zamanda olası zararlarından korunmak içinde gerekli mühendislik çalışmalarının yapılması oldukça önemlidir. Bu amaçla inşa edilen baraj, sedde, regülatör, köprü, menfez, savak ve taşkın koruma yapılarının su yüzü profillerine etkisinin değerlendirilmesi, planlama, uygulama, işletme mühendisleri için ve ayrıca taşkın sigortalama çalışmaları içinde gereklidir. Su yapılarının projelendirilme ve ekonomik analiz çalışmaları yoğun hesaplama ve tekrarlı yöntemler içermektedir. Günümüzde gelişen, daha büyük ve karmaşık hale gelen bu projelerdeki hesaplamaların hızlı ve doğru bir şekilde yapılabilmeleri için bilgisayar kullanımı kaçınılmaz olmaktadır. Su yapıları mühendislik uygulamaları için geliştirilmiş, hesap ve analiz kolaylığı sağlayan birçok paket program bulunmaktadır.
Bu programlardan birisi de Amerika Birleşik Devletleri Askeri Mühendislik birimi tarafından geliştirilen HEC-RAS (Hydrologic Engineering Centers River Analysis System), paket programıdır. HEC-RAS paket programı doğal akarsular ve sonradan inşa edilmiş açık kanallardaki akımların bir boyutlu hidrolik hesabını gerçekleştirmek üzere geliştirilmiş grafik tabanlı, kapsamlı bir yazılımdır. Program düzenli ve değişken akımlarda su yüzü profili hesaplamaları, sediment taşınım/hareketli taban hesaplamaları, su kalitesi analizleri ve birçok hidrolik yapı hesaplamaları yapabilmektedir. HEC-RAS paket programı http://www.hec.usace.army.mil/software/hec-ras/ sitesinden ücretsiz olarak indirilebilmekte ve kullanılabilmektedir. Sitede ayrıca program hakkında detaylı bilgi veren yardımcı dokümanlara ulaşılabilmektedir. Bunlardan en önemlileri kullanım kılavuzu “User’s Manual”, hidrolik hesap yöntemlerini açıklayan “Hydraulic Reference Manual” ve uygulama örnekleri ve açıklamalarını içeren “Applications Guide” dır.
Bu kitapta HEC-RAS programında kullanılan açık kanal akımlarına ait hidrolik hesaplama yöntemleri ve bazı örnek uygulamalar ele alınmıştır. Ayrıca bir laboratuvar kanal modeli üzerindeki farklı su yapılarına ait geliştirilen uygulamalar ve gerçek bir taşkın düzenleme yapısına ait örnek paylaşılmıştır.
Bu kitap altı bölümden oluşmaktadır. Birinci bölümde HEC-RAS paket programı hakkında genel bilgiler verilerek, hesaplamalarda kullanılan denklemler açıklanmıştır (Hydraulic Reference Manual, Chapter 2). Ayrıca program ara yüzü ve kullanımı detaylı olarak ele alınmıştır (Hydraulic Reference Manual, Chapter 3). Birinci bölümde program uygulama dosyasındaki (Application Guide, Chapter 1) eğimli dere (Örnek 1) ve ayrıca laboratuvar kanalının modellenmesine ait bir çalışma (Örnek 2)açıklanmıştır. Bu bölümde ayrıca Application Guide, Chapter 8 de verilen kapalı göz oluşturan nehir örneği (Örnek 3) ve yine aynı kaynakta Chapter 10 da verilen kesişen akarsu kollarına ait örnek (Örnek 4) ele alınmıştır.
İkinci bölümde köprü yapılarının HEC-RAS ile nasıl modelleneceği, kullanılan denklemler ve yaklaşımlar (Hydraulic Reference Manual, Chapter 5) açıklanmış, Application Guide, Chapter 2 de verilen tek açıklıklı köprü örneği (Örnek 5) ele alınmıştır. Bu bölümde ayrıca laboratuvar kanalı üzerinde bulunan tek ve iki açıklıklı köprü yapısının nasıl modelleneceği açıklanmıştır (Örnek 6).
Üçüncü bölümde menfez yapılarının HEC-RAS da modellenmesi, kullanılan denklemler ve yaklaşımlar (Hydraulic Reference Manual, Chapter 6) açıklanmış, Application Guide, Chapter 3 de verilen, benzer varilli tek menfez örneği (Örnek 7) ve aynı kaynakta bulunan (Chapter 4) çoklu menfezler Örnek 8 de ele alınmıştır. Bu bölümde ayrıca laboratuvar kanalı üzerinde bulunan tek menfez çoklu varillerin nasıl modelleneceği Örnek 9 da açıklanmıştır.
Dördüncü bölümde HEC-RAS ile bir kesitte çoklu köprü ve/veya menfez açıklıklarının modellenmesi (Hydraulic Reference Manual, Chapter 7) ele alınmıştır. Application Guide, Chapter 5 de verilen çoklu açıklıklar örneği (Örnek 10), Chapter 7 de verilen çoklu plan örneği (Örnek 11) ve yine aynı kaynak Chapter 9 da verilen karışık akım analiz örneği (Örnek 12) açıklanmıştır.
Beşinci bölümde kapaklı savak, sedde ve düşü yapılarının modellenmesi (Hydraulic Reference Manual, Chapter 8) ele alınmıştır. Application Guide, Chapter 12 de verilen enkesit yapıları örneği (Örnek 13) ayrıca laboratuvar kanalı üzerinde bulunan geniş başlıklı savak ve yan savak yapılarının nasıl modelleneceği açıklanmıştır (Örnek 14).
Altıncı bölümde ise taşkın koruma yapılarının su yüzü profillerine etkisi (Hydraulic Reference Manual, Chapter 9) ele alınmıştır. Application Guide, Chapter 6 da verilen taşkın kanalı hesaplamalarına ait örnek (Örnek 15) ve yine aynı kaynak Chapter 16 da verilen kanal düzenlenmesi örneği (Örnek 16) açıklanmıştır. Son olarak Örnek 17 de Kayseri, Talas ilçesinde bulunan Deliçay taşkın deresinin hidrolik modellemesi yapılmıştır.
Bu kitabın su yapıları konularında çalışan akademisyenler, planlama ve uygulama mühendisleri ve özellikle su kaynaklarına ilgi duyan inşaat mühendisliği lisans ve lisansüstü öğrencilerine yararlı olmasını dilerim. Akademik hayatımda bana her zaman destek ve rehber olan saygı değer hocam Prof. Dr. M. Salih KIRKGÖZ’e sonsuz teşekkürlerimi sunarım. Kitap üzerindeki olası öneri, eleştiri ve hataların iletilmesi durumunda daha faydalı bir kaynak olacağı düşüncesiyle, hayırlı olmasını diliyorum.

Bridges are very important and costly structures lot of birr is spending for the construction hence hydrological investigations are highly recommended for the proper design and durability of bridge. The proposed study area is located at main Degan Town with Rassa Keble and Argoba Woreda Chelka river Ethiopia.The main objective of this study is to carry out hydrological and hydraulics investigations of the Chelka river, to determine its different return floods values in order to find the proposed bridge opening to provide bridge design parameters such as size and location of the bridge and exploring details like geomorphology, soil and land use or land cover, analysis of rainfall intensity. The mean annual rainfall ranges between 400mm-799mm. The mean annual moderate warm temperature is 120oc to 350oc, altitude from 1300-3000m. HEC-RAS (Version-4) software model has been used for determination of proposed bridge layout and the water surface profile. The hydrologic and hydraulic analysis of Catchments delineation is done by GIS Environment by using GIS Software’s like Arc View

In this study, water rising due to the flood which is at Akkışla Bridge located at Ova Creek was analyzed using a river analysis software program, HEC-RAS. Unsteady flow simulations were performed using different flood hydrographs and it is observed that the free surface flow level rises above the bridge deck for 500-year flood discharge. Three different flood control types which are taking the peak discharge to flood retarding pool via the side weir, changing the slope of the river and changing the river cross section were applied and their results were compared. It is obvious that the maximum level of water surface at bridge cross section can be reduced 1.5 m by changing river morphology. According to the results of analyses, applicability of these three flood control types were discussed. The most appropriate flood control method was suggested, these three flood control methods were compared in terms of economy.
Keywords: Flood, Side Weir, River Morphology, HEC-RAS

High dams have been/are being constructed along the R.Nile for various uses thus creating a cascade arrangement in the same flow valley. It is because of this setup that the possibilities of hazards resulting from exceedingly excess discharge from one upstream Dam due to different reasons, puts the downstream structures at danger as well as the environment. Particularly, this study was prompted considering the prevalence of the Nalubaale Hydropower Dam wall which surpassed its design life. This dam also has the largest reservoir in the world of 270 BCM. This paper gives insights of real time management of a cascade. It covers design requirements, modelling, simulation and instruments involved and their relevance in the automation of the spillways to suit a safe existence of Cascade dams. Implementation improved the operation and management of Hydro Power Plants in the following ways: Reduce the chances of over topping in any of the dams in the cascade, Reduce chances of over flooding of any one reservoir, Reduce the risk of dam wash away and failure of the structures, Reduce the chances of unnecessary spilling of water in the reservoirs, Helps to guide decision making during capacity tests and improves Emergency Preparedness and Response actions for Cascade dams. 2.0 METHODS AND APPROACHES USED 2.1 Conceptual design To study the cascade system, one has to zero to two dams at a time. In this method, focus was given to the first two Dam walls (taking Nalubaale and Kiira as one since they are in parallel) while basing at Bujagali HPP.

This article shows a pliable unified modeling scheme applying a materially based, distributed, integrated hydrological
and water quality modeling organization. It is need to analyze the unsteady flow in open channels network is done using
the computer packages, because solving the Saint-Venant equation is very difficult and sophisticated spatially for a
network of channels. The unsteady flow can be analyzed by Saint-Venant equations. These equations can be solved by
characteristics and finite difference methods. The HEC-RAS program applies the second method. 
This program need to data such as: scheme of network channels, geometric properties of cross sections, initial discharge
and boundary condition. The outputs of this program are: Surface profiles, flow hydrograph and distribution of flow
velocity in each cross section etc. In this research an example was solved in unsteady flow using HEC-RAS. In this
procedure, the energy and duration equations are decided for steady, slowly diverse flow by the Newton–Raphson
procedure and the offered methodology is used to tree-type and looped-channel networks. An algorithm is introduced to
define numerous critical depths in a compound channel. Corrections in channel geometry are provided to prevent the
incidence of, many critical depths. The incidence of only one critical depth in an implicate cross section with improved
geometry is shown for a tree-type channel network.

Resumen: Este estudio tiene como objetivo analizar la inundación causada por la falla hipotética de la Presa Mulacorral, cuyo embalse está localizado en la cuenca alta del río Ambato en la cota 3831 msnm. La presa está ubicada a 42 kilómetros en dirección noroeste de la ciudad de Ambato, capital de la Provincia de Tungurahua, Ecuador. Para el análisis, se consideró una longitud de cauce de 50 kilómetros aproximadamente, desde el pie de la presa hasta los límites de la ciudad de Ambato, en el sector de la planta de tratamiento de aguas residuales. Se ejecutó 10 planes de simulación considerando: el modo de la falla de la presa (tubificación y desborde), opciones de cómputo y tolerancias del programa. Los resultados fueron verificados con ecuaciones de regresión, desarrolladas con base en antecedentes históricos. Los escenarios de rotura presentan en todos los casos niveles de agua que alcanzan la estructura de la vía Flores e infraestructura que se encuentra en las riberas del río Ambato, en un margen promedio de 100 metros. De los escenarios de rotura planteados, se destaca el modelo que utiliza la Ecuación de Froehlich (2008) para falla por desborde, ya que presenta resultados conservadores, un caudal pico máximo de 1271 m3/s y un tiempo de llegada de 2 horas con 20 minutos a la ciudad de Ambato.

Abstract: This study aims to analyze the flood caused by the hypothetical failure of the Mulacorral Dam, whose reservoir is located in the upper basin of the Ambato River at 3831 meters above sea level. The dam is located 42 kilometers northwest of Ambato city, capital of the Tungurahua Province, Ecuador. For the analysis, a length of approximately 50 kilometers was considered, from the dam foot to the limits of the Ambato city, in the wastewater treatment plant sector. Ten simulation plans were executed considering: the dam failure mode (piping and overflow), computation options and program tolerances. The results were verified with regression equations, developed based on historical background. In all cases, the failure scenarios present water levels that reach the Flores Avenue structure and infrastructure located on the banks of the Ambato River, in an average margin of 100 meters. Of the breakage scenarios proposed, the model used by the Froehlich Equation (2008) for overflow failure stands out, since it presents conservative results, a maximum peak flow of 1271 m3/s and a time of arrival of 2 hours and 20 minutes to the Ambato city.

The fact that, in the Ozana drainage basin, most of the people have built their homes in the river valley, determines that a study focused on identifying the areas exposed to
hydrological risk is vital, mostly in the development decisions for villages and in the creation of management plans for emergency situations. This study analyses the mapping methodology of the flood prone areas in the middle and lower sector of the Pluton river, which is a tributary of Ozana river, in its upper sector. In order to correctly draw the flood risk maps, the HEC-RAS method has been used, together with the HEC-GeoRAS extension, in ArcGIS. The results that have been obtained, correlate with the field situation in a very high proportion: for a 1% occurance flood, almost 123 households have been damaged, and according to the
simulation, a number of 147 buildings have been damaged, therefore other probabilities (that overcome the 1% situation) can be used for similar simulations.

River flooding causes several human and financial casualties. It is necessary to perform research studies and implement subsequent actions consistent with the nature of the river. In order to reduce flood damage, floodplain zoning maps and river cross-sectional boundaries are important to nonstructural measures in planning and optimizing utilization of the areas around the river. Due to the complex behavior of the rivers during floods, computer modeling is the most efficient tool with the least possible cost to study and simulate the behavior of the rivers. In this study, one-dimensional model Hydrologic Engineering Centers—River Analysis System and two-dimensional model CCHE2D were used to simulate the flood zoning in the Sungai Maka district in Kelantan state, Malaysia. The results of these two models in most sections approximately match. Most differences in the results were in the shape of the river.

There are different natural hazard, among these different natural hazards flood are most devastating and frequently occurring calamities taking human lives and causing economic damages. This report has been prepared to present hazard analysis mapping of flood of Punyamata River as a project work of 4th year student. The main focus of this project work was to determine the Elements at risk of the Punyamata River and to create flood hazard zone mapping of following years return period (5, 10, 20, 50, and 100). This project work explores the element at risk of the study area. The user’s requirement is extracted by experts view in qualitative way and system requirements are extracted by practice. Data requirement for flood hazard mapping are extracted from expert’s view and literatures. The hazard class map was performed by flood simulation process. Contours can be extracted from the system for Digital Elevation Model (DEM). The hazard map of various years return period and effected buffer zones are the main outputs from the system.

The U.S. Army Corps of Engineers' Hydrologic Engineering Center's River Analysis System (HEC-RAS) is a widely used software application for performing one-dimensional and two-dimensional steady and unsteady flow river hydraulics calculations, sediment transport-mobile bed modeling, and water quality analysis. User's of HEC-RAS have often unique applications including the coupling with other software to perform system analysis such as optimization of flooding structures and multi-objective reservoir operation under uncertainty. One state-of-the-art environment for integrating software is MATLAB, which integrates computation, visualization, and programming in an easy-to-use environment. This paper presents a set of MATLAB scripts to write input files, read output files, make plots, execute parallel computations , and perform fully-automated functions of HEC-RAS. Examples of procedures are presented throughout the paper and they are illustrated using a river-reservoir network that involves ten inline structures (e.g., dams) with operation of gates at each of these dams.

HEC-RAS is aplication programming which is used to river flow modelling all of river section so we can know characteristic flow and pattern. HEC-RAS modelling used several data such as in this article. So, if you want to know this article. Please download and read the article. Thank you..
(Note: In this article using Indonesia language)

Lacey’s equation is often used to find out the scour depth in rivers in India. Lacey’s regime formula
(1930) was developed on the basis of limited field data from irrigation canals in Punjab Province having
discharge ranges from 0.70 to 173 m3/s. The total scour at a highway crossing is comprised of three
mechanisms: long-term aggradation-degradation, contraction of reach, and local scours at piers and
abutments. In the present study, HEC-RAS model is used to estimate the bridge scour for the Ganges
road bridge and it is then compared with Lacey’s formula. Apparently, more realistic results are
obtained by HEC-RAS model as it considers more related factors as angle of attack, bed conditions,
shape of piers, flow concentrations, flow depth and Froude No. as against discharge intensity and silt
factor considered in case of Lacey’s equation. Comparative study is carried out for different angles of
attack and restricted flow condition near the bridge site. From the restriction of waterway by 3.6 km to
2 km, abutment scour and contraction scour change 1.6 times and 3.9 times respectively. So, the
waterway has significant role for the bridge foundation design. By changing angle of attack by 5 °, the
change in pier scour is 10%.

Bangladesh is a low lying riverine country formed by a deltaic plain at the confluence of the three mighty rivers Ganges, Brahmaputra, Meghna and their tributaries. Most of the flows of these major rivers are connected to the Bay of Bengal through Meghna Esuary. The Lower Meghna River with a very dynamic estuarine system conveys the maximum flow through the estuary to the Bay of Bengal during dry and wet season . The sediment load and flow volume in Lower Meghna is respectively the highest and the third highest (after Amazon and Congo) in the world (Ahmed S. 1998). Owing to this tremendous water volume and sediment load delivered by the rivers, the estuary is an area of an active land erosion-accretion and dynamic water circulation. The main physical processes in the estuary are mainly dependent on the estuarine morpho-dynamics that causes erosion and accretion in the scale of hundred sq. kilometers per year and cause several thousands of people to become landless and homeless every year (Biswajit et al., 2013) 2000-2013. Net accretion, net erosion and the erosion trend are derived from the image processed using ILWIS 3.7.2 and ArcMAP 10. It is obvious that the erosion rate was in decreasing order from the year 1973 to 1984, 3.4km2/yr to -8.4km2/yr. Analysis also showed that in the history of the last forty years erosion rate was higher from the year 2003 to 2005, -8.4km2/yr to 15.4km2/yr. Recent year analysis predicted that the deposition is higher than the erosion. However, further research should be focused on future channel shifting pattern, erosion rate and vulnerability of different locations as well as determining effective measures to decrease erosion severity and its consequences.

Flood is one of the natural disasters which occur in Myanmar every year. Flooding of rivers has caused many humans and financial losses. Flood inundation mapping is an essential component of flood risk management because flood inundation maps not only provide accurate geospatial information about the extent of floods, but also, can help decision-makers extract other useful information to assess the risk related to floods such as human loss, damages, and environmental degradation. Chindwin River Basin is located in the western part of Myanmar and floods often occur seriously in monsoon season. In order to perform river flood inundation mapping, HEC-HMS and HEC-RAS were utilized as hydrological and hydraulic models, respectively. The model consists of a rainfall-runoff model (HEC-HMS) that converts precipitation excess runoff, as well as a hydraulic model (HEC-RAS) that models unsteady state flow through the river channel network based on the HEC-HMS-derived hydrograph. Three flood events were applied to calibrate and validate the results. The highest depth of inundation can seriously affect the Homalin and Mawlaik and U Yu tributary.

Penelitian ini dilakukan pada penggal Sungai Code antara stasiun Pogung hingga Kaloran, Yogyakarta untuk melakukan pemodelan tiga dimensi terhadap debit sungai. Parameter statis meliputi data geometrik sungai dan nilai koeffisien kekasaran manning yang disadap menggunakan data penginderaan jauh dan dimodelkan dengan bantuan  perangkat lunak GIS dan HEC-RAS. Sedangkan data dinamis adalah input debit sungai yang diperkirakan antara julat minimum hingga debit maksimum yang diperkirakan dari data sekunder. Sebagian besar data geometrik sungai disadap langsung dari data penginderaan  jauh dengan ketelitian yang tinggi. Data-data geometrik yang 100% diperoleh dari data  penginderaan jauh antara lain garis tengah sungai, cekungan, aliran dan penampang melintang. Ketelitian data yang disadap dari data penginderaan jauh untuk nilai koeffisien kekasaran manning adalah sebesar 93,75%. Sedangkan data geometrik yang dibangkitkan dari hasil delineasi menggunakan data penginderaan jauh dan peta RBI digital dengan hasil akhir yang direkonstruksi dari pengukuran lapangan menggunakan teodolit. Hasil pengukuran menggunakan teknik fotogrametri untuk menyadap data ketinggian bangunan sekeliling lokasi memiliki nilai m.sq.e sebesar 0.323 dibandingkan dengan pengukuran di lapangan. Prototipe Sistem visulisasi debit tiga dimensi merupakan hasil utama penelitian ini. Perangkat lunak ini disusun dari hasil pemodelan menggunakan GIS dan HEC-RAS untuk menampilkan ketinggian muka air dari perhitungan debit dan kondisi terain sungai secara tiga dimensi. Tampilan sistem informasi yang interaktif disusun menggunakan  bahasa pemrograman Avenue Arcview dan Visual basic dari data-data penginderaan jauh dan survey lapangan. Hasil penelitian menunjukkan bahwa data penginderaan jauh dan peta RBI digital dapat digunakan untuk menyadap parameter lahan dan data geometrik yang dapat digunakan untuk melakukan pemodelan
steady flow. Ketelitian hasil pemodelan tergantung dari ketelitian DEM. Data penginderaan jauh juga dapat dimanfaatkan untuk hasil akhir berupa visualisasi yaitu dengan membuat DTM.

HEC-RAS merupakan program aplikasi yang digunakan untuk memodelkan suatu aliran sungai/saluran sehingga kita bisa mengetahui pola serta karakteristik aliran di sepanjang section sungai. Pada tulisan ini merupakan tinjauan aliran permanen (steady flow) model hidrodinamika. So, Let's check...

O Brasil, frente aos acidentes ocorridos em Mariana – MG (2015) e em Brumadinho – MG (2019), tem vivenciado inúmeras discussões no que tange à assuntos regulatórios e à confiabilidade das barragens construídas no país. Neste trabalho, inicialmente, fez-se um breve comparativo entre a legislação brasileira e alguns normativos internacionais (China, Portugal, Estados Unidos e África do Sul) sobre segurança de barragens, observando-se a existência de diferentes aspectos abordados entre eles. A Política Nacional de Segurança de Barragens se demonstrou uma das regulamentações menos rígidas entre as analisadas quanto a pré-requisitos técnicos para sua aplicação, deixando grande parte das barragens de pequeno porte dispensadas do cumprimento de algumas obrigações. Além disto, a legislação federal brasileira foi implementada há menos de uma década, o que implica, atualmente, em uma dificuldade muito grande do empreendedor, dos órgãos fiscalizadores e do governo federal a se adaptarem a possuir esta cultura de segurança de barragens. Diante da interface destas construções com o meio ambiente, faz-se necessário um monitoramento constante das estruturas por uma equipe multidisciplinar e um programa de segurança consistente que vise garantir a integridade do meio ambiente nas áreas de influência das barragens, bem como resguardar o bem-estar e a vida da população situada a jusante. O uso de funções matemáticas e softwares para o mapeamento das áreas sujeitas aos riscos impostos pelas barragens é um avanço grandioso no aspecto de segurança destas estruturas. Neste contexto, o presente estudo teve por objetivo prático principal analisar a influência da cobertura do solo das áreas de preservação permanente (APPs) a jusante da barragem da PCH Pedra Furada, localizada no município de Ribeirão no estado de Pernambuco, sobre características de manchas de inundação referentes a vazões hipotéticas para tempos de retorno de 10 e 10.000 anos, defluentes deste empreendimento. Foram utilizados dados de levantamento de campo como ortofotos e topografia (obtidas por VANT) assim como informações batimétricas cedidos pela empresa proprietária do empreendimento e, também, dados hidrológicos da Agência Nacional de Águas. Por meio da simulação do modelo hidrodinâmico bidimensional HEC-RAS 5.0.7, em regime transiente, variou-se os coeficientes de rugosidade (Manning) das faixas marginais ao rio Sirinhaém, fazendo-se análises em seções distantes 5, 15 e 25 km do barramento. Os resultados demonstraram que para um aumento de oito vezes da rugosidade da APP, reduziu-se o tempo de chegada de onda em 2h50 min para o cenário de TR=10 anos e em 2h10min para o cenário de TR=10.000 anos na seção distante 25 km da barragem. Já para a seção mais próxima ao barramento, este aumento de rugosidade levou ao acréscimo de profundidades da água de, cerca de, 2 metros dentro da calha fluvial, para ambos cenários de vazão. Assim, conclui-se que APPs vegetadas representam menor intensidade sobre planícies de inundações mais próximas do barramento, enquanto que, para as planícies mais distantes, representam uma janela de tempo maior para a implementação de ações contingenciais, caracterizando-se, assim, como uma boa contribuição para o rol de elementos de segurança de barragens.

Sistem drainase di jalan Garuda Sakti masih belum berfungsi secara maksimal. Hal ini dapat terlihat dari ketidakmampuan saluran drainase dalam mengalirkan debit limpasan. Banjir yang terjadi menyebabkan kemacetan arus lalu lintas serta mengganggu kegiatan belajar mengajar di Sekolah Dasar yang terletak di sekitar lokasi penelitian. Analisa banjir dilakukan dengan menganalisa kapasitas saluran dan membandingkanya dengan debit yang dihitung dengan metode Rasional. Analisa kapasitas drainase dihitung dengan menggunakan software HEC-RAS 4.1.0. Analisa profil dilakukan dengan 2 jenis simulasi dengan 3 kala ulang yang berbeda, yaitu 5 tahun, 10 tahun, dan 20 tahun. Hasil penelitian menunjukkan bahwa pada kondisi eksisting diketahui bahwa tinggi genangan maksimum yang terjadi yaitu 14,30 cm untuk kala ulang 5 tahun, 16,40 cm untuk kala ulang 10 tahun dan 17,40 cm untuk kala ulang 20 tahun. Simulasi dengan cara mengatur kemiringan memanjang saluran menjadi 0,0003 hanya mampu menanggulangi banjir hingga 68,11% untuk kala ulang 5 tahun, 59,09% untuk kala ulang 10 tahun dan 52,01% untuk kala ulang 20 tahun, sedangkan simulasi dengan cara penggalian kedalaman saluran mampu menanggulangi banjir secara maksimal.

Kejadian banjir yang terjadi di Sitiarjo memiliki debit yang besar dan melimpah dalam waktu singkat. Kejadian banjir mengindikasikan perlu adanya pengelolaan air. Pemanenan air hujan bertujuan agar air hujan tidak langsung menjadi limpasan permukaan, namun dapat ditampung dan dikelola. Tujuan dari penelitian ini adalah membuat model hujan aliran menggunakan metode SCS CN, merekonstruksi banjir yang terjadi pada DAS Penguluran pada kejadian 10 Juli 2013, menganalisis efektivitas sumur resapan dalam mengurangi debit banjir pada kejadian banjir 10 Juli 2013.

Teknik analisis yang digunakan adalah dengan menggunakan model SCS CN pada perangkat lunak HEC HMS dan penggunaan perangkat lunak HEC RAS untuk model estimasi ketinggian banjir. Kapasitas tampung maksimal sumur resapan ditentukan berdasarkan Peraturan Bupati Kabupaten Malang No. 8 Tahun 2015.

Model hujan-limpasan pada DAS Penguluran menghasilkan parameter DAS berupa nilai bilangan kurva, initial abstraction dan lag time. Pada kejadian banjir tanggal 10 Juli 2013, hujan yang terjadi pada durasi 5 jam, sehingga terjadi debit puncak sebesar 641 m3/s dengan volume aliran sebesar 9.268 m3. Zona dampak banjir terdapat di lokasi hilir sungai DAS Penguluran pada lokasi Dusun Pulungrejo dan Dusun Sitiarjo yang berada di meander sungai dengan ketinggian banjir pada outlet DAS setinggi 2 meter di atas saluran sungai. Efektivitas sumur resapan untuk menurunkan debit puncak yang jumlahnya ditentukan berdasarkan Peraturan Bupati Kabupaten Malang Nomor 8 Tahun 2015 memiliki tingkat efektivitas 40,81%, sedangkan pada sumur resapan yang jumlahnya ditentukan berdasarkan jumlah total rumah hanya memiliki tingkat efektivitas sebesar 21,67% untuk dapat menurunkan debit puncak pada alur sungai.

ÖNSÖZ
Doğal afetlerin önüne geçebilmek mümkün olmasa da, yıkıcı etkilerini azaltarak can ve mal kaybını en aza indirmek günümüz bilgi ve teknolojileri ile sağlanabilmektedir. Artan nüfus ve sanayinin gelişimine bağlı yüksek sera gazı salınımları, iklim değişikliği tehlikesini de beraberinde getirmiş, bu değişime bağlı su kaynaklarının yönetimi daha da önemli hale gelmiştir. Akarsu yatağının su iletim kapasitesinin çeşitli sebeplerle azalması veya kapasiteden daha fazla suyun gelmesi halinde yatak dışına taşarak can ve mal kaybına sebep olan taşkınlar, tedbir alınması gereken önemli afetlerdendir. Taşkınlar yerleşim alanlarına, altyapı tesislerine, tarım arazilerine, insanların sosyal ve ekonomik hayatlarına, önemli zararlar verebilmektedir.
Amerika Birleşik Devletleri Askeri Mühendislik birimi tarafından geliştirilen HEC-RAS (Hydrologic Engineering Centers River Analysis System), paket programı, 2017 yılında yayınlanan AÇIK KANAL AKIMLARI ve HEC-RAS UYGULAMALARI kitabımda örnek uygulamalar ile ele açıklanmıştır. Programın güncel 5.X sürümlerinde bir boyutlu (1D) modelleme özelliğinin yanı sıra iki boyutlu (2D) akım modelleme özelliği eklenmiştir. Programda ihtiyaç duyulan arazi topoğrafik ve morfolojik bilgilerine, uydu verileri ve hava fotoğrafları kullanılarak ulaşılabilmektedir. Topoğrafyanın sayısal gösterimi olan Sayısal Yükseklik Modeli–SYM, (Digital Elevation Model-DEM), günümüzde, SRTM, ASTER, LANDSAT gibi uydu verileri ile üretilebilmektedir.
Yeni sürümlere eklenen HEC-RAS Mapper özelliği ile program, açık kanal akımlarında çok amaçlı hesaplamaları birlikte gerçekleştirebilecek kapasitede tasarlanmış bütünleşik bir yazılım sistemidir. Program grafik tabanlı ara yüz ile düzenli akım su yüzü profil hesaplamaları, bir (1D) ve iki boyutlu (2D) değişken akım modellemeleri, yarı ve tam değişken akım katı madde taşınım modellemeleri ve su kalite analizlerini gerçekleştirebilmektedir. Sonuçların tablo ve grafiksel olarak görüntülenmesi, taşkın yayılma haritalarının oluşturulması ve animasyonu, raporlanması ve depolanması yapılabilmektedir.
Bu çalışmamda, programın güncel sürümlerine eklenen HEC-RAS Mapper modülü açıklanarak 1D modellemenin yanı sıra 2D taşkın modelleme ve 1D/2D birleşik taşkın modelleme uygulamaları ele alınmıştır. Kitabın ilk bölümünde iki boyutlu akım modelleme özellikleri, avantajları ve kısıtları açıklanmıştır. İkinci bölümde 2D modelleme için gerekli arazi modellerinin geliştirilmesi, üçüncü bölümde 1D/2D birleşik model geliştirilmesi, dördüncü bölümde birleşik modelin çalıştırılması, beşinci bölümde sonuçların RAS Mapper ile görüntülenmesi açıklanmıştır. Altıncı bölümde düzenli akım modellemesine ve değişken akım modellemesine ne zaman ihtiyaç duyulacağı, 1D nehir kolu ve 2D akım alanı veya depolama alanlarının nerede kullanılacağı konuları ele alınmıştır. Yedinci bölümde örnek uygulamalarda ele alan Çamaşırcı deresi ve taşkın debileri hakkında bilgiler verilmiştir.
Çamaşırcı deresinde iki farklı periyottaki (Q25 ve Q100) taşkın debileri için düzenli ve değişken akım analizleri gerçekleştirilmiştir. Uygulama 1 de Çamaşırcı deresi ve yan kolu olan Baruthane deresi doğal kesiti, 1D olarak modellenmiştir. Uygulama 2 de Çamaşırcı deresi düzenlenmiş mevcut kanal durumunda sanat yapıları (köprü ve menfezler) dikkate alınmadan 1D olarak modellenmiştir. Uygulama 3 de Çamaşırcı deresi düzenlenmiş mevcut kanal durumu, köprü ve menfezler dikkate alınarak 1D olarak modellenmiştir. Uygulama 4 de mevcut duruma taşkın koruma amaçlı bir kapak yerleştirilerek düzenli ve değişken akım analizleri gerçekleştirilmiştir. Uygulama 5 de Çamaşırcı deresinde iki boyutlu (2D) değişken akım analiz yapılarak taşkın sınırları belirlenmiştir. Son olarak Uygulama 6 da Çamaşırcı deresinde 1D/2D birleşik akım analizi yapılarak taşkın sınırları belirlenmiştir.
Uygulamalarda ele alınan Çamaşırcı deresine ait bilgiler, 2019 yılında Gezer Endüstri İnşaat ve Tic. A.Ş. için hazırlanan, “İstanbul Çamaşırcı Deresinin HEC-RAS ile Taşkın Analizi ve Çözüm Önerileri Raporu” kapsamında yapılan ölçüm ve incelemelerden alınmıştır. Bu vesile ile arazi ölçümlerinde yardımcı olan firma yetkililerine ve özellikle Makine Mühendisi Suat BALAMİR beye teşekkürlerimi arz ederim.
Bu yeni kitabımın su yapıları konularında çalışan akademisyenler, planlama ve uygulama mühendisleri ve özellikle su kaynaklarına ilgi duyan inşaat mühendisliği lisans ve lisansüstü öğrencilerine yararlı olmasını dilerim. Kitap üzerindeki olası öneri, eleştiri ve hataların iletilmesi durumunda daha faydalı bir kaynak olacağı düşüncesiyle, hayırlı olmasını diliyorum.

Prof. Dr. Mehmet ARDIÇLIOĞLU
      Temmuz 2020 – KAYSERİ
Web Adresi: www.mehmetardiclioglu.com
E posta      : [email protected]

HEC-RAS dan HEC-GeoRAS merupakan perangkat lunak yang dikembangkan oleh Hydrologic Engineering Center (HEC). Perangkat lunak ini cukup populer digunakan dalam analisis yang berkaitan dengan hidrolika aliran saluran terbuka. Komputasi aliran permanen di HEC-RAS menerapkan model satu dimensi (1D). Makalah ini mengambil rangkum langsung, konsep komputasi hidrolika HEC-RAS dan HEC-GeoRAS dari banyak sumber yang secara umum dari terjemahan langsung manual book, buku literatur, modul dan lain-lain yang berkaitan dengan model hidrolika komputasi saluran terbuka, HEC-RAS dan HEC-GeoRAS. Sangat disarankan untuk membaca terlebih dahulu sumber-sumber yang ada di referensi sebelum membaca makalah ini. 2016 1 Gambar 1. Karakteristik Dataran Banjir Sumber: Federal Emergency Management Agency (2009)

River flow predictions are needed in many water resources management. The beginning of the modern study of unsteady flow in open channels can be traced to the latter half of the nineteenth century when the French engineer Saint-Venant introduced the partial differential equations of continuity and momentum governing free surface flow in open channels. These equations are highly nonlinear and therefore do not have analytical solutions. The computer revolution in twentieth century made a new era where numeric methods can be utilized effectively to solve nonlinear partial differential equations. This paper presents the results of two different numerical methods, namely; Preissmann and Lax diffusive schemes for numerical solution of Saint-Venant equations that govern the propagation of flood wave, in natural rivers, with the objective of the better understanding of this propagation process. The results have shown that the hydraulic parameters play important game in the flood wave propagation. The results of these numerical solutions are compared with the HEC-RAS commercial computer model.

"En la modelación matemática de crecidas, la disponibilidad de datos topográficos o hidráulicos en una escala espacial y temporal determinada, constituyen los datos esenciales de entrada. Los datos topográficos disponibles, generalmente poseen baja resolución para modelaciones hidrodinámicas detalladas, siendo las técnicas fotogramétricas más precisas pero más costosas. Para superar estas limitaciones, se utilizó un modelo digital de elevaciones (MDE) global de acceso público, al cual se le realizaron arreglos planialtimétricos e hidrológicos.
Se presentan comparaciones, ajuste altimétrico y validación de cinco MDE: SRTM en sus versiones v2.1, SRTM30 y SRTM-v4.1 en banda C; SRTM en banda X y ASTER-GDEM. Estos dos últimos con 30 m de resolución y de 90 m los primeros. El objetivo del estudio, es cuantificar el error vertical de cada MDE, y establecer cuál es el más apropiado, para la aplicación de un modelo hidrodinámico del tramo inferior del río Tunuyán en la provincia de Mendoza.
La metodología está basada en análisis estadísticos de residuales altimétricos, calculados a partir de los MDE e información de referencia (redes geodésicas y puntos GPS a lo largo del cauce). Estos métodos, son útiles cuando la información topográfica de detalle, perfiles transversales y áreas de inundación, no están disponibles.
Se concluye que SRTM-v4.1 presenta el mayor grado de precisión, y que llevado a una resolución de 30 m, podría servir como entrada detallada al modelo, en zonas con datos escasos y en escalas de trabajo del orden de 1:100.000, siendo necesario: reconstruir, validar y calibrar el MDE.
Este trabajo se realizó dentro del marco del proyecto “Actualización de la crecida de proyecto, simulación matemática de las condiciones de rotura de la presa El Carrizal, áreas inundables y Plan de Acción De Emergencia” Convenio entre el Ministerio de Infraestructura de la Provincia de Mendoza y el INA."

Flooding of rivers has caused many human and financial losses. Hence, studies and research on the nature of the river is inevitable. However, the behavior of rivers has many complexities and in this respect, computer models are efficient tools in order to study and simulate the behavior of rivers with the least possible cost. In this paper, one-dimensional model HEC-RAS was used to simulate the flood zoning in the Kota Tinggi district in Johor state. Implementation processes of the zoning on catchment for return periods of 2, 25, 50 and 100 years were applied with different roughness coefficients. In order to improve the results of flood zoning from the obtained results, it is better to include the items for changing hydraulic platform as a different scenario's problem. The sensitivity of HEC-RAS model to the roughness coefficient, the coefficient of narrowing and opening, and energy slope were examined and observed. The most sensitive on water surface profile is created by the changes in the roughness coefficient. The volume and upstream surface runoff area and stream or flood conditions and physical characteristics of the area (surface morphology, etc.) can be named as the most significant factors that can affect the severity and recurrence of floods in every region.

La villa turística El Rodeo, ubicada a 38 Km de la capital de Catamarca, está atravesada por el Río Ambato, de tranquilas aguas durante el estiaje pero cuyas crecidas, más frecuentes en verano, generaron inconvenientes tanto en puentes como en las viviendas ubicadas en las márgenes. Luego de realizar un estudio hidrológico de la cuenca cabecera, y determinados los caudales de diseño para recurrencias de hasta 200 años, se realizó una modelación matemática del régimen hidráulico cuyos resultados de tirantes y velocidades permitieron establecer el riesgo de los distintos sectores de la villa. El riesgo de inundaciones fue conformado, además de la peligrosidad del evento, a través de las vulnerabilidades físicas y las exposiciones de edificaciones e infraestructura, como así también de personas y vehículos. Se presenta la metodología empleada y los resultados obtenidos, información de base a ser utilizada en una futura gestión integrada de crecidas.

Since the most economic-agricultural activities in areas adjacent to the river is in flood plains, including a discussion on the management of these areas is the considerable, zoning map has an important effect on flood management, The right of the river bed, and the economic feasibility of development projects, forecast, warning and rescue operations and flood insurance could be included. Using computer models and using geographic information systems incorporating GIS as well as hydraulic and hydrologic models are the common methods of floodplain zoning maps. There are a variety of different performance capabilities and access to the data required by this model, so that we have to choose the best software related to that model. In this article, we try to introduce a few well-known models for floodplain zoning maps; some of the capabilities and applications are considered by some approaches. At the end, we express the factors that are affecting the accuracy of results.

Aquatic habitat assessment and river restoration design require geospatially explicit maps of hydraulic conditions. Diverse mechanistic ecohydraulic models compute spatially explicit depth and velocity results to evaluate habitat suitability spatially as a function of these abiotic conditions. This study compared depth and velocity results from two-dimensional (2D) and one-dimensional (1D) hydraulic models with algorithms that laterally discretize 1D velocity and interpolate depth and velocity spatially based on the Laplacian heat mapping approach.  These ‘conveyance distributed’ methods constitute ‘best 1D modeling practice’, and were compared to 2D results for the first time. The 1D and 2D models were applied to three morphologically distinct reaches (leveed, meandering, and anastomosing) for three flows (base, bankfull, and flood flows) of the partially regulated, gravel/cobble lower Yuba River in north-central California.  The test metrics were the coefficient of determination (R2) and the median absolute residual (|ε ̃ |).  These metrics quantified the incremental uncertainty 1D approximation incurs, results which make explicit cost-benefit processes of model selection possible.  Finally, velocity residual maps were analyzed to identify regions and processes where residuals were high, indicating divergence from the 1D assumptions. Paired data (1D-2D) fell between 0.94 ≥R2≥1.00 (R2mean=0.98 and R2median=0.99) for depth and median absolute residuals were all 3.8≤|ε ̃ |≤7.2% (i.e. 50% of residuals are approximately within ±1.7 to 3.6%).  Higher flows and lower gradient reaches had lower residuals and higher R2.  Velocity diverged more, particularly for base flow in anastomosing reaches (0.42<R2<0.58).  One-dimensional, conveyance distributed, assumptions performed better for other channel types, where 0.69 < R2 < 0.81 (R2mean=0.75 and R2median=0.77), with median absolute residuals between 9.6%> |ε ̃ |  >22.4% (i.e. ~±4.6 to ±11.2%), where |ε ̃ |mean =14.2% and |ε ̃ |median =13% (~±7.1 and 6.5%).  The conveyance distributed 1D velocity model performed best where the orthogonal flow assumptions obtained and where side channels did not transition from backwater to conveying area between flows.

Two multi-storied occupied apartment buildings and a clinic of 'Red-Cross Society' in Chandernagore-a former French colony, located very close to the banks of tidal river 'Hooghly' (the southernmost part of River Ganges-the major hydrodynamic system that formed the world's largest delta) are standing precariously, following some recurrent slides of high riverbank during the last year's monsoons. The area where the ground caved in, is on the end of the famous Strand Bank Road (in Hooghly district of West Bengal in India); which is supposed to be the best decorated bank of the river 'Ganges' along its entire length of 2500 km. The opposite river bank is an official sand mining site. The river over considerable stretch at both upstream and downstream apparently seemed stable when analyzed over an extensive temporal domain from old Survey of India toposheets, recent satellite imagery, digital elevation model, field hydrographical survey synthesized in Geographical Information System (GIS) platform. A closer look into the geotechnical aspects supported by subsurface exploration, post failure on-site exposures and stability analysis revealed certain startling facts when considered in association with the hydro-meteorological factors and fluvial dynamics. An in-depth study of the factors responsible for the localized erosion is presented based on site observations and evidences, analyzed in association with real time hydrological and meteorological data.

Floods are regular feature in rapidly urbanizing Dhaka, the capital city of Bangladesh. It is observed that about 60% of the eastern Dhaka regularly goes under water every year in monsoon due to lack of flood protection. Experience gathered from past devastating floods shows that, besides structural approach, non-structural approach such as flood hazard map and risk map is effective tools for reducing flood damages. In this paper, assessment of flood hazard by developing a flood hazard map for mid-eastern Dhaka (37.16 km 2 ) was carried out by 1D hydrodynamic simulation on the basis of digital elevation model (DEM) data from Shuttle Radar Topography Mission and the hydrologic field-observed data for 32 years . As the topography of the area has been considerably changed due to rapid land-filling by land developers which was observed in recent satellite image (DigitalGlobe image; Date of imagery: 7th March 2007), the acquired DEM data were modified to represent the current topography. The inundation simulation was conducted using hydrodynamic program HEC-RAS for flood of 100-year return period. The simulation has revealed that the maximum depth is 7.55 m at the southeastern part of that area and affected area is more than 50%. A flood hazard map was prepared according to the simulation result using the software ArcGIS. Finally, to assess the flood risk of that area, a risk map was prepared where risk was defined as the product of hazard (i.e., depth of inundation) and vulnerability (i.e., the exposure of people or assets to flood). These two maps should be helpful in raising awareness of inhabitants and in assigning priority for land development and for emergency preparedness including aid and relief operations in high-risk areas in the future.

The River Analysis System (HEC-RAS) software was used to simulate the free flow over the broad-crested single-step weir. The software was used to compute the water surface profile, determine the location of the hydraulic jump,
and establish the head-discharge relationship for the weir. The simulation results were verified by a series of laboratory measurements using a horizontal flume 5 m long, 0.45 m deep and 0.30 m wide. The tested weir had the following dimensions: total length was 48 cm; length of the downstream step of the weir was 24 cm; total height was 24 cm; height of the downstream step of the weir was 12 cm. Different inflow rates were applied to the weir for tail water depths of 6, 8, 10, 12 and 14 cm under free flow conditions. It was found that HEC-RAS could capture the overall features of the flow
profile over the weir with reasonable accuracy. HEC-RAS could also determine the location of the hydraulic jump. It also produced a head-discharge relationship well close to the measured data. Besides, HEC-RAS was found easy to use for this specific flow problem and performed the computations in a short time.

Bridges are very important and costly structures lot of birr is spending for the construction hence hydrological investigations are highly recommended for the proper design and durability of bridge. The proposed study area islocated at main Degan Town with Rassa Keble and Argoba Woreda Chelka river Ethiopia.The main objective of this study is to carry out hydrological and hydraulics investigations of the Chelka river, to determine its dif erent return floods values in order to find the proposed bridge opening to provide bridge design parameters such as size and location of the bridge and exploring details like geomorphology, soil and land use or land cover, analysis of rainfall intensity. The mean annual rainfall ranges between 400mm-799mm. The mean annual moderate warm temperature is 120oc to 350oc, altitude from 1300-3000m. HEC-RAS (Version-4) software model has been used for determination of proposed bridge layout and the water surface profile. The hydrologic and hydraulic analysis of Catchments delineation is done by GIS Environment by using GIS Software’s like Arc View.

Sediment deposition in a reservoir decreases storage capacity and effects many other parameters of the reservoir adversely. It reduces benefits and useful life of a hydro power project that have huge socioeconomic impacts. Flushing is one of the techniques to remove sediments from reservoirs. This study investigates sediment accumulation, transportation and flushing using both the physical and numerical modeling. Gulpur Hydro Power Project (HPP) on Poonch River in Pakistan was chosen for this purpose. The geometry, cross-sections and other physical attributes of the Poonch River were prepared and hydraulic structures were placed on the basis of topographic survey using AutoCAD. Physical model of scale 1:40 was developed at Nandipur Research Station in Pakistan. After base test the model was used to get data for various scenarios of sediment flows. HEC-RAS was used for numerical simulations. Delta profile and flushing were simulated. Delta modeling was made for hourly time step for 20 years of sediment deposition with average discharge conditions, whereas, suitable flushing durations were predicted for various flushing discharges to de-silt yearly deposited sediments. Simulation showed that life of the un-sluiced Gulpur HPP is about 14-15 years. To enhance the life of project, annually 4-5 days are required for flushing with 250 m 3 /s discharge.