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1

Flood Vulnerability Mapping and Risk Assessment Using Hydraulic Modeling and GIS in Tamanrasset Valley Watershed, Algeria

Madi Housseyn, Bedjaoui Ali, Elhoussaoui Abdelghani, Elbakai Lala Oulad, Bounaama Aya

Journal of Ecological Engineering

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2023

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Vol. 24, nr 7

35--48

EN

The paper is focused on the integration of the US Army Corps of Engineers Hydrologic Engineering Center (HEC) models, particularly the HEC-RAS (River Analysis System) 1D hydraulic model, into a decision support system for predicting the effects of floods. The study was conducted in the Tamanrasset Valley watershed in Algeria, where the HEC-RAS model was used to calculate water flow profiles for various flood events that occurred downstream. The objective of the study was to generate flood maps for extreme river flood events in the area, which could help assessing the risk of flood vulnerability in the area study. The process involved using the HEC-RAS 1D model to simulate the water flow in the river, taking into account the various flow and boundary conditions. The results of the simulation were then exported and analyzed in GIS-based software, HEC-GeoRAS, to prepare the flood inundation maps. The flood maps were based on the water level at each cross-section, which was calculated using the water surface profiles generated by HEC-RAS. The study aimed to identify flood zones using a combination of HEC-GeoRAS and GIS. The HEC-GeoRAS extension was utilized in a GIS environment to determine flood zones associated with 10-year, 20-year, 50-year, and 100-year return periods. The results of the study confirmed the effectiveness of the integration of GIS and HEC-RAS and demonstrated the performance of the model. Based on these findings, the study recommends the application of this model in planning and management programs for both residential and agricultural areas, to ensure appropriate measures are taken for future flood defense.

2

Badania numeryczne języka rozdzielczego poniżej jazu na stopniu wodnym Januszkowice na rzece Odrze

Filipczyk Janusz Michał, Mokwa Marian, Kędzia Dawid, Krasodomski Jerzy, Dorada Paweł, Radecki-Pawlik Artur

Gospodarka Wodna

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2022

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Nr 6

5--11

PL

W pracy przedstawiono wyniki dwuwymiarowych badań modelowych języka rozdzielczego poniżej jazu na stopniu wodnym Januszkowice. Praca jest wynikiem projektu realizowanego przez PBW Inżynieria z Wrocławia celem poprawy warunków korzystania z wód i przeprowadzania przepływów powodziowych na rzece Odrze.

EN

The paper presents the results of two-dimensional modeling of the diversion dam downstream of the weir in Januszkowice. The work is the result of a project carried out by designing office PBW Inżynieria in Wrocław. The aim of the project was to improve the conditions for the use of water and the discharge of floods in the Odra River, Poland.

3

Flash Flood Risk and Climate Analysis in the Extreme South of Algeria (the Case of In-Guezzam City)

Zegait Rachid, Pulido-Bosch Antonio, Hamadeha Bachir, Şen Zekai, Madi Housseyn

Geomatics and Environmental Engineering

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2022

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Vol. 16, no. 4

157--185

EN

Natural risks, particularly flood risk, are a topical subject in Algeria and throughout the world, particularly given the last major catastrophic floods in Sudan (2020) and North Africa. With the development of the climate change phenomenon in the world, risk management is becoming increasingly necessary for all the actors concerned (decision-makers, technicians, and the population) to identify protection issues. In 2018, in the extreme south of Algeria, In-Guezzam City suffered a devastating flood that caused significant damage and loss of human and material resources. More than 100 homes collapsed, and approximately 345 families were displaced. Currently, there is no research work to assess the hydrological situation and the risk of flooding in this region. Therefore, the main purpose of this study is to shed light on the risk of flash floods in the extreme south of Algeria with more specific attention to the August 2018 floods as well as the climate trends over the past 30 years using Mann–Kendall test and Sen’s Slope Estimator. The chosen approach involves a hydrological study and hydrodynamic modeling using HEC-RAS software. This latter allows for simulating floods using statistical methods and creating several regional flood hazard maps.

4

Water Quality Modelling of the Sebou River Estuary (Morocco) before and after the Installation of the Kenitra City's Wastewater Treatment Plant

Nizar Youness, Touazit Azzeddin, Igouzal Mohamed

Ecological Engineering & Environmental Technology

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2022

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Vol. 23, iss. 6

264--274

EN

Urban wastewaters from Kenitra had been discharged without prior treatment through six collectors into the Sebou estuary (60 km) causing in the process health and environmental problems up until WWTP was installed in 2020. The waste water treatment plant (WWTP) had to gather all urban wastewaters in order to go through treatment. Thus, the WWTP, situated 17 km from the mouth of the estuary, has become the only discharge point for treated domestic wastewater into the Sebou estuary. This study aims to model the Sebou estuary water quality and assessment of the impact of WWTP. Our study started with hydraulic modelling of the river using a 1D model (HECRAS 5.0.6), since water quality is strongly depending on hydraulic regime. HEC RAS has been calibrated and validated using hydraulic and morphological database of the years 2019 and 2021. The spatiotemporal evolution of hydraulic variables (water velocity, water level, etc.) was calculated by the hydraulic model and used in the water quality module to simulate the biochemical oxygen demand (BOD5). Two scenarios were put under examination, one is a simulation of discharges of untreated wastewaters by six collectors (mean BOD5 of 300 mg/L) and the second is a simulation of discharge after treatment at the WWTP (mean BOD5 of 24 mg/L). The simulation showed an Impact of the tidal cycle and fresh water flows (coming from the upstream) on the urban wastewater discharges fate. Calculations of the BOD5 provided by the model are in good agreement with field measurements. The first simulation results show that water quality of the Sebou River does not meet WHO standards (average quality about 7 mg/l of BOD5). The second simulation shows that the treatment plant reduces the concentration of BOD5 in the river to about 3 mg/l compared to the case before their installation, the quality of the water in the estuary is changing to become good after having been just average. In addition, the BOD5 concentration downstream of the WWTP changes according to the tidal cycle. Finally, the results show the very positive impact of Kenitra’s WWTP on the water quality of the Sebou River estuary.

5

Flood Frequency Analysis and Hydraulic Design of Bridge at Mashan on River Kunhar

Riaz Khuram, Aslam Hafiz Muhammad Shahzad, Yaseen Muhammad Waseem, Ahmad Hafiz Haseeb, Khoshkonesh Alireza, Noshin Sadaf

Archives of Hydro-Engineering and Environmental Mechanics

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2022

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Vol. 69, nr 1

1--12

EN

Kunhar River hydrology and hydraulic design of a bridge on this river are being studied using HEC-Geo-RAS and Hydrologic Engineering Centers River Analysis System (HEC-RAS). The river flows in the northern part of Pakistan and is 170 km long. On both sides of the river, there are residential settlements. The river hydraulics is studied by using 30-metre remotely sensed shuttle radar topographic mission - digital elevation model (SRTM DEM) and Arc Map. 32 cross-sections are imported from Geographic Information System (GIS) to HEC-RAS. On historical peak flow results, the extreme value frequency distribution is applied, and a flood is determined for a 100-year return period, with a discharge estimated as 2223 cubic metres. Three steady flow profiles are adopted for HEC-RAS, the first is for the maximum historical peak data, the second is for the 100-year return period, and the third profile is for the latter 100-year period with a safety factor of 1.28. With remote sensing-based assessments, the proposed location for a bridge is determined and then verified with a field survey which was physically conducted. The maximum water height estimated in the river is about 4.26 m. This bridge will facilitate about 50 thousand population of Masahan and its surroundings. It will create a shortest link between Khyber Pakhtunkhwa and Azad Kashmir and thus will enhance tourism and trade activities.

6

Evaluating lateral riverbank erosion with sediment yield through integrated model in lower Gangetic floodplain, India

Ghosh Arnab, Roy Malabika Biswas, Roy Pankaj Kumar

Acta Geophysica

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2022

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Vol. 70, no 4

1769--1795

EN

One of the natural disasters caused by river meandering is riverbank erosion, which creates social, economic, and environmental problems in the riparian zone and serves as a source of increasing sedimentation levels in the river. Riverbank erosion and bank failure create a complex cyclical process, such as riverbank retreat, which cannot be easily measured and predicted by any model. The meandering flow along the Bhagirathi-Hooghly river has created riverbank erosion and riverbank retreat conditions in several areas, through which measuring bank stability and erosion is quite complex. As a result, the BSTEM model, integrating with HEC-RAS, has been used in this article to measure riverbank erosion and retreat accurately. Riverbank erosion and retreat data for 2019–2020 have been simulated based on data observed from 2016 to 2018 for accurate measurement. In addition, the total sediment yielded from the river bank has been calibrated and simulated with the help of sediment transport formulation in HEC-RAS, which indicates a gradual increase in river erosion at present (2019–2020). This model is expected to help formulate government policy on protecting riverbank erosion and river restoration in the future.

7

HEC-RAS and GIS based food plain mapping: A case study of Narai Drain Peshawar

Salman Awais, Hassan Sher Shah, Khan Gul Daraz, Goheer Muhammad Arif, Khan Aftab Ahmad, Sheraz Khurram

Acta Geophysica

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2021

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Vol. 69, no. 4

1383--1393

EN

Flood computer modeling is one of the recent practices which is used for the prediction of the food occurrence at diferent intervals of time. A study was conducted on Narai Drain Hayatabad, Peshawar, to produce food plain maps by integrating Arc-GIS with the Hydraulic Modeling software HEC-RAS. The area in the vicinity of Narai Drain was inundated due to the catastrophic food occurred in the year 2010, which caused huge damage to public property, livestock, communication, and infrastructure. In this study, the Narai Drain watershed was classifed into three watersheds, namely Narai Drain Upper, Lower, and Regi Drain. GIS technology was used to delineate the watersheds while the discharges were computed using the WinTR-20 mode. Expected rainfall depths were obtained by using Log-Pearson type III Distribution for diferent return periods (i.e., 2, 5, 10, 25, 50, 100, 200). The area inundated by the food was estimated by using HEC-RAS. These results were then incorporated in GIS to prepare food inundation maps. Maximum inundation occurred in the sensitive area of Narai Drain Lower for a 10-year return period. The integrated modeling approach used in this study was found very useful to delineate the area vulnerable to food with a good estimation of inundation depths at various discharge values. The results show that in the upper reach of the Narai Drain, most of the area lying near the food zone was safe for a 100-year return period, while the lower reach was vulnerable even for a return period of 10 years.

8

Use of modelling for the renovation of drainage channels – The case of the Bouteldja plain in northeastern Algeria

Sennaoui Foued, Benabdesselam Tamara, Saihia Abdallah

Journal of Water and Land Development

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2019

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no. 43

1--8

EN

Agricultural drainage has become a priority in agriculture and the economic development of the state. Algeria has launched several agro-economic projects pertaining to natural resources and human potential for development in agricultural areas. Our aim is to model the morphological evolution of open drainage channels, under the influence of sedimentary transport processes. The application of the Hydrologic Engineering Center’s River Analysis System (HEC-RAS) software is to examine two-phase mathematical models. In our case it is the flow and the sedimentary charge along a trapezoidal earth channel of a wetland north east of Algeria. The results of these models were validated by actual data obtained during the observation period from 2017 to 2018, for various rainy events. The solid transport and sedimentation velocity equations of Engelund and Hansen and Van Rijn respectively used by this model, give Nash performance criteria equal to 0.95 and determination coefficient R2 equal to 0.91. On the other hand, the laying of a coarse gravel layer of median diameter of the grains d50% = 60 mm on the bottom of the channels reduces the rate of sedimentation by about 32% over an 11-year period. This satisfying objective study of the modelling allows to obtain an approach to the renovation and a plan for new design of drainage systems, that participates to the sustainable development in the agricultural field.

PL

Drenowanie stało się priorytetem w rolnictwie i gospodarczym rozwoju kraju. W Algierii uruchomiono kilka programów rolniczych odnoszących się do zasobów naturalnych i potencjału rozwojowego obszarów wiejskich. Naszym celem było modelowanie zmian morfologicznych w otwartych kanałach drenarskich pod wpływem procesów transportu zawiesiny. W dwufazowym modelu matematycznym wykorzystano program HEC-RAS (Hydrologic Engineering Center’s River Analysis System). Zmiennymi w modelu były przepływ i ładunek zawiesiny wzdłuż ziemnego kanału o trapezoidalnym przekroju w środowisku podmokłym północnowschodniej Algierii. Wyniki modelu porównano z rzeczywistymi danymi opadowymi pozyskanymi w różnych okresach w latach 2017 i 2018. Równania Engelunda i Hansena (transport zawiesiny) i Van Rijna (tempo sedymentacji) użyte w modelu dały w wyniku kryterium Nasha równe 0,95 i współczynnik determinacji R2 równy 0,91. Warstwa grubego żwiru o medianie średnic ziaren d50% = 60 mm na dnie kanału spowalniała tempo sedymentacji o ok. 32% w ciągu 11 lat. Przedstawione badania umożliwiają nowe podejście do renowacji istniejących i projektowania nowych systemów drenarskich, które przyczyniają się do zrównoważonego rozwoju rolnictwa.

9

Preliminary assessment of the impact of Wrocławski bridge in Gliwice on flood flow in Kłodnica river

Mikołajczyk Bartłomiej, Michalec Bogusław, Strutyński Mateusz

Geomatics, Landmanagement and Landscape

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2019

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no. 4

231--241

EN

In this work, a preliminary assessment has been made of the impact that the bridge along Wrocławska and Częstochowska streets has on the conditions of flood flow. Calculations were made for a flow with a probability of exceedance p = 1% amounting to 100 m3 · s–1. Based on the field tests performed in the designated section of the Kłodnica river from km 49 + 799 to km 49 + 739, i.e. geodetic measurements of the Kłodnica riverbed and technical inventory of the analysed bridge object, a digital terrain model (NMT) was developed, followed by hydraulic calculations of the water flow Q1% and the flow accumulation (damming) in the clear span of the Wrocławski bridge. The accumulation height was calculated using the formula given in the study by Bajkowski et al. [2000]. Calculations of the accumulation height of designed flow in the clear span of the bridge were also made using the HEC-RAS program. The calculations were made in two variants – in the first variant, calculations were performed for the selected section of Kłodnica without a bridge, and in the second variant, with the bridge. The so-called clear span reserve (bridge clearance) was also calculated, computed as the difference in ordinates of the keystone arch of the bridge span and the stacked water table of the design flow in the bridge clear span. The obtained calculation results indicate no risk of Q1% flow accumulation in the cross-section of the Wrocławski bridge. The calculated accumulation of the design flow will not cause flooding from the Kłodnica riverbed. Preliminary conclusions indicate a possible necessity to verify flood hazard zones for the flow with a probability of exceedance p = 1%, developed for the Kłodnica river in the centre of Gliwice town, developed as part of the ISOK project.

PL

W niniejszej pracy dokonano wstępnej oceny wpływu mostu w ciągu ulic Wrocławskiej i Częstochowskiej na warunki przepływu wód wezbraniowych. Obliczenia wykonano dla przepływu o prawdopodobieństwie przewyższenia p = 1%, wynoszącego 100 m3·s—1. Na podstawie wykonanych badań terenowych na przyjętym odcinku rzeki Kłodnicy od km 49 + 799 do km 49 + 739, tj. pomiarów geodezyjnych koryta Kłodnicy i inwentaryzacji technicznej analizowanego obiektu mostowego, opracowano numeryczny model terenu (NMT), a następnie wykonano obliczenia hydrauliczne przepływu wody Q1% i wysokości spiętrzenia tego przepływu w świetle mostu Wrocławskiego. Wysokość spiętrzenia obliczono za pomocą wzoru podanego w opracowaniu Bajkowskiego i in [2000]. Wykonano także obliczenia spiętrzenia przepływu obliczeniowego w świetle tego mostu za pomocą programu HEC–RAS. Obliczenia wykonano w dwóch wariantach – w wariancie pierwszym wykonano obliczenia dla wytypowanego odcinka Kłodnicy bez mostu, a w wariancie drugim z mostem. Obliczono również tzw. zapas w świetle mostu, jako różnicę rzędnych zwornika łuku przęsła mostu i spiętrzonego zwierciadła wody przepływu obliczeniowego w świetle mostu. Uzyskane wyniki obliczeń wskazują na brak zagrożenia spiętrzenia przepływu Q1%, w przekroju mostu Wrocławskiego. Obliczone spiętrzenie przepływu obliczeniowego nie spowoduje wystąpienia wód tego przepływu z koryta Kłodnicy. Stwierdzono wstępnie ewentualną konieczność weryfikacji stref zagrożenia powodziowego dla przepływu o prawdopodobieństwie przewyższenia p = 1%, opracowanych dla rzeki Kłodnicy w centrum Gliwic, opracowanych w ramach projektu ISOK.

10

Prognozowanie zmian korytotwórczych w uregulowanym korycie rzeki Czarny Dunajec z wykorzystaniem modelu jednowymiarowego

Plesiński K., Radecki-Pawlik A., Michalik P.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2017

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Vol. 26, No. 3

346--360

PL

W pracy przedstawiono prognozę zmian korytotwórczych w korycie rzeki uregulowanej za pomocą bystrza o zwiększonej szorstkości. Obszar badań znajdował się na rzece Czarny Dunajec i obejmował swoim zasięgiem 100-metrowy odcinek koryta powyżej bystrza o zwiększonej szorstkości i 65 m poniżej. Na podstawie pomiarów terenowych, modelowania numerycznego oraz z użyciem wykresu Hjulströma określono miejsca, w których występuje erozja koryta, transport lub sedymentacja rumowiska. Modelowanie numeryczne przeprowadzono dla przepływu wezbraniowego Qwez = 16,9 m3·s–1, zaobserwowanego w rzece 5 sierpnia 2013 roku, oraz dla przepływów prawdopodobnych: Q50% = 59 m3·s–1, Q25% = 99 m3·s–1, Q10% = 165 m3·s–1 i Q1% = 321 m3·s–1. Podjęto także próbę wyznaczenia dla badanego odcinka rzeki wartości przepływu korytotwórczego.

EN

Along the paper, we presented an analysis of changes of cross-sections morphology within the regulated reach of a mountain river. The river engineering works there were done by building cable block ramp. The studied reach was located in the Czarny Dunajec river. Analyzed reach of the river consisted of 100-m long segment upstream of the existing block ramp and 65 m downstream of it. The analysis was done based on field measurements, numerical modeling with HEC-RAS and Hjulström’s graph. Numerical modeling was conducted for observed flood Qfl ood = 16.9 m3·s–1 on 5 August 2013, and for the t-years floods: Q50% = 59 m3·s–1, Q25% = 99 m3·s–1, Q10% = 165 m3·s–1 and Q1% = 321 m3·s–1. For the analyzed reach an attempt was done to determinate dominant discharge.

11

Sediment transport modelling in wadi Chemora during flood flow events

Berghout A., Meddi M.

Journal of Water and Land Development

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2016

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no. 31

23--31

EN

The 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.

PL

Ruch rumowiska jest zjawiskiem złożonym ze względu na jego nieciągły charakter oraz losowe, zmienne w czasie i przestrzeni warunki transportu. Ze względu na swoją skalę stanowi on główne ograniczenie rozwoju, zmniejsza pojemność zbiorników wodnych oraz pogarsza stan innych budowli wodnych. W pracy przedstawiono wyniki modelowania transportu rumowiska w uedzie Chemora (Batna, Algeria) za pomocą programu HEC-RAS. W tym celu wykorzystano dane hydrometryczne (przepływu wody i transportu rumowiska) zarejestrowane w czterech przekrojach wodowskazowych zlokalizowanych w zlewni rzeki Chemora, dane z Numerycznego Modelu Terenu (NMT) zlewni oraz charakterystyki litologiczne koryta. Do analizy wyników modelowania wykorzystano parametry zarejestrowane w czasie dwóch wezbrań powodziowych w rzece Chemora (pierwsze wystąpiło w całej zlewni, drugie – w jej części), takie jak: objętość transportu rumowiska, początkowa objętość rumowiska (na wejściu do systemu) i końcowa (na wyjściu z systemu) oraz miejsca narażone na erozję i akumulację rumowiska.

12

Modelling approach for gravity dam break analysis

Boussekine M., Djemili L.

Journal of Water and Land Development

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2016

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no. 30

29--34

EN

The construction of dams in rivers can provide considerable benefits such as the supply of drinking and irrigation water; however the consequences which would result in the event of their failure could be catastrophic. They vary dramatically depending on the extent of the inundation area, the size of the population at risk. This paper presents an analysis of dam break model of Hammam Grouz in Algeria, for 100-years recurrence flood with the dam break occurring near the peak of the flood event. The software HEC-RAS was used to determine water-surface profiles of in-place and dam break scenario, this model supports on the resolution of the equation of Saint-Venant for unsteady flow analysis. Inundation maps were developed that shown the estimated extent of downstream floodwaters. Simulation results were used to determine the hazard classification of a dam break.

PL

Budowa zapór na rzekach przynosi znaczące korzyści w postaci dostawy wody pitnej i wody do nawodnień, jednakże konsekwencje wynikające z ich przerwania mogą być katastrofalne. Skutki przerwania zapory zależą od wielkości zalanego obszaru i wielkości populacji zagrożonej ryzykiem. W pracy przedstawiono modelową analizę przerwania zapory Hammam Grouz w Algierii w przypadku stuletniej fali powodziowej i przerwania zapory powstałego blisko szczytu fali powodziowej. W celu oznaczenia profili powierzchni wody w wariancie prawidłowym i w przypadku przerwania zapory użyto programu HEC- -RAS. Model bazuje na rozwiązaniu równania Saint–Venanta do analizy przepływów nieregularnych. Utworzono mapy zalewów, które pokazują zasięg wód powodziowych poniżej zapory. Wyniki symulacji użyto do klasyfikacji ryzyka przerwania zapory.

13

The Possibilities of Using Hec-Ras Software For Modelling Hydraulic Conditions of Water Flow in the Fish Pass Exampled by the Pomiłowo Barrage on The Wieprza River

Hammerling M., Walczak N., Walczak Z., Zawadzki P.

Journal of Ecological Engineering

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2016

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Vol. 17, nr 2

81--89

EN

The aim of the article is to analyse hydraulic conditions of water flow in a fish pass. The test facility is part of the Pomiłowo barrage in the commune of Sławno, Poland. The authors applied HEC-RAS software for modelling hydraulic parameters of the water flow in the fish pass. The data from field measurements was implemented in the software and calculations of changes in the water table in the fish pass were made. The results confirmed the usefulness of HEC-RAS software for estimating hydraulic parameters of water flow in a fish pass. HEC-RAS software enables to take into account the parameters responsible for the phenomena accompanying the flow through a fish pass. Selecting mathematical model parameters (coefficients) should be preceded by a multidimensional analysis of the facility. More precise information on hydraulics, hydrology and biology of the test fish pass are also required.

14

A GIS based approach for the prediction of the dam break flood hazard – A case study of Zardezas reservoir “Skikda, Algeria”

Derdous O., Djemili L., Bouchened H., Tachi S. E.

Journal of Water and Land Development

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2015

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no. 27

15--20

EN

The construction of dams in rivers can offer many advantages, however the consequences resulting from their failure could result in major damage, including loss of life and property destruction. To mitigate the threats of dam break it is essential to appreciate the characteristics of the potential flood in realistic manner. In this study an approach based on the integration of hydraulic modelling and GIS has been used to assess the risks resulting from a potential failure of Zardezas dam, a concrete dam located in Skikda, in the North East of Algeria. HEC- -GeoRAS within GIS was used to extract geometric information from a digital elevation model and then imported into HEC-RAS. Flow simulation of the dam break was performed using HEC-RAS and results were mapped using the GIS. Finally, a flood hazard map based on water depth and flow velocity maps was created in GIS environment. According to this map the potential failure of Zardezas dam will place a large number in people in danger. The present study has shown that Application of Geographical Information System (GIS) techniques in integration with hydraulic modelling can significantly reduce the time and the resources required to forecast potential dam break flood hazard which can play a crucial role in improving both flood disaster management and land use planning downstream of dams.

PL

Budowa zapór na rzekach może przynosić wiele korzyści, jednakże ich przerwanie może skutkować poważnymi stratami, włączając w to utratę życia czy zniszczenie mienia. Aby zmniejszyć zagrożenia wynikające z przerwania tamy, należy uwzględnić charakterystykę prawdopodobnej powodzi w sposób realistyczny. W przedstawionej pracy zastosowano podejście polegające na zintegrowaniu modelowania hydraulicznego z GIS w celu oceny ryzyka potencjalnego zniszczenia betonowej zapory Zardezas zlokalizowanej w Skikda w północno-wschodniej Algierii. Do uzyskania danych geometrycznych z cyfrowego modelu wysokości użyto HEC-GeoRAS pracującego w GIS. Dane te następnie wprowadzono do HEC-RAS. Symulacje przepływu po przerwaniu zapory przeprowadzono z użyciem HEC-RAS, a wyniki przedstawiono w postaci mapy z użyciem GIS. Na koniec utworzono w środowisku GIS mapę ryzyka powodziowego na podstawie danych o głębokości wody i prędkości przepływu. Według tej mapy, potencjalne przerwanie zapory Zardezas stworzy zagrożenie dla znacznej liczby ludności. Badania wykazały, że zastosowanie technik GIS w połączeniu z modelowaniem hydraulicznym może znacząco zmniejszyć czas i ograniczyć zasoby niezbędne do prognozowania zagrożenia powodzią po przerwaniu tamy. Uzyskane wyniki mogą pełnić ważną rolę w zarządzaniu ryzykiem powodziowym i w planowaniu przestrzennym terenów położonych poniżej zapory.

15

Modelowanie transportu rumowiska w zbiorniku Jezioro Kowalskie na rzece Głównej

Jaskuła J., Wicher-Dysarz J., Dysarz T., Sojka M.

Inżynieria Ekologiczna

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2015

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Nr 43

131--138

PL

Celem pracy była analiza zmian geometrii czaszy zbiornika wywołanych akumulacją rumowiska. Zbiornik Jezioro Kowalskie jest zbiornikiem dwustopniowym, górna część jest oddzielona od głównego zbiornika zaporą w Jerzykowie. Podjęto próbę określenia wpływu dwustopniowej budowy zbiornika na kształtowanie się układu dna przy różnych warunkach przepływu. Symulacje przeprowadzono za pomocą programu HEC-RAS 5.0.0 Beta. Natężenie transportu rumowiska obliczono dwoma formułami: England-Hansena oraz Meyer Peter i Mullera. Wyniki obliczeń wykazały, że zmiany położenia dna wywołane procesami erozji i akumulacji występują w wydzielonej części wstępnej. Przyjęte wartości przepływów nie mają istotnego wpływu na geometrię zbiornika głównego, jego układ jest podobny zarówno w zakresie przepływów od NNQ do WWQ. Wyniki wykazały, iż budowa zbiorników z wydzieloną częścią wstępną jest skutecznym rozwiązaniem zapobiegającym zamulaniu zbiorników retencyjnych.

EN

The purpose of the presented research is the analysis of bed elevation changes caused by sediment accumulation in the Jezioro Kowalskie reservoir. The Jezioro Kowalskie reservoir is a two stage reservoir constructed in such a way that the upper preliminary zone is separated from the main part of the reservoir. The split of the reservoir parts is done with a small predam, located in Jerzykowo town. The analysis of such a construction impact on changes of bed elevations in the reservoir in different flow conditions is presented. The HEC-RAS 5.0 Beta model is used for simulations. The sediment transport intensity is calculated from England-Hansen and Meyer-Peter and Muller formulae. The results showed the processes of sediment accumulation and slight erosion occuring in the preliminary zone of the reservoir. The choice of the flow intensity does not have a huge importance. Similar results are obtained for low as well as high flows. The results confirm, that two stage construction with separated preliminary zone is effective method preventing from the sedimentation of the reservoir.

16

Application of HEC-RAS model for estimating changes in watercourse geometry during floods

Markowska J., Markowski J., Drabiński A.

Studia Geotechnica et Mechanica

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2012

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Vol. 34, nr 2

63-72

EN

The article describes the progress of a hypothetical flood in a watercourse reach, including potential changes in the channel geometry. The quasi-hydrodynamic model employed takes into account changes in the temperature of the medium over time, the complex structure of the watercourse channel, almost any recharge pattern and any engineering structures in the channel. As a result, it is possible to estimate probable changes in the geometry of precisely reproduced reaches of existing watercourse channels during significant floods and include them, e.g., in real-time operational models.