year 12, Issue 3 (Autumn 2022)
E.E.R. 2022, 12(3): 190-210 |
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Esfandiari Darabad F, Nezafat Taklreh B, Paseban A H. Morphological Simulation of Flood Occurrence in Nooranchai River Using HEC-RAS Hydraulic Model. E.E.R. 2022; 12 (3) :190-210
URL: http://magazine.hormozgan.ac.ir/article-1-713-en.html
URL: http://magazine.hormozgan.ac.ir/article-1-713-en.html
Department of Natural Geography, Faculty of Social Sciences, Mohaghegh Ardabili University. , fariba.darabad@gmail.com
Abstract: (1962 Views)
1-Introduction
Rivers are considered as the main sources of water for humans and other organisms, and sometimes this source of life causes destruction and irreparable damage. Predicting the hydraulic behavior of rivers in the face of potential floods to reduce damage to urban and rural areas, facilities under construction, farms and other existing uses around the river is of particular importance (Askari et al., 2014) because they can be used to provide measures and solutions to control floods and minimize the damage caused by it. One of the key topics in geomorphology, engineering and river management is the morphology of river canals, which provides useful information about the geometric shape, bed shape, longitudinal profile, cross sections and their deformation and location over time (Yamani et al, 2012). ). Hejazi et al. (2020) zoned for flood risk in the Varkeshchay catchment using the HEC-RAS model. The results of these researchers showed that 110 km of the total catchment area is affected by floods with a return period of 50 years and 63 km of it is affected by floods with a return period of 25 years. Shafiei Motlagh and Ebadati (2020) used HEC-RAS software (Case study: Maroon River - southwest of Iran) to perform zoning of the flood and simulating the hydraulic behavior of the river. They concluded that the flood area for different return periods of 5, 10, 25 and 50 years is equal to 1265, 1651, 2334 and 4450 hectares, respectively, and the number of endangered villages is equal to 5, 3, 2 and 9, respectively. In a study aimed at producing flood risk maps in Kazakhstan, Ongdas et al. (2020) stated that the village of Volgo was flooded during a 100-year flood event. Aynalem (2020), in a study on the Muga River, reported floodplains for 5, 10, 25, 50, and 100-year return periods of 18, 21, 26, 34, and 43 km2, respectively. Therefore, the aim of the present study is to morphologically simulate the occurrence of floods in the Nooranchay River using the HEC-RAS hydraulic model.
.2- Methodology
Geological maps 1: 100000, topographic maps 1: 50000, and 1: 2000, data of synoptic stations, rain gauges, and flowmeters are among the most basic data of the present study which were prepared by Ardabil Regional Water Organization. HEC-RAS software or software river US Army Engineering is a set of tools that allows the user to perform river hydraulic calculations in steady-state and non-steady-state flow. The HEC-RAS system includes three components of one-dimensional hydraulic analysis to perform water level profile calculations in steady-state flow, non-steady-state simulation and sediment transport calculations at the moving boundary. These three components share a common geometric representation and use the same geometric and hydraulic calculation process is set of tools that can be used in the GIS software environment. This add-on creates a link between ArcGIS software and HEC-RAS software, and is specifically designed for spatial data processing for use in RAS modeling and for processing RAS results in the GIS environment. Processing ground data and other GIS data in ArcGIS software using GEO-RAS allows the user to create and export a geometric file for RAS analysis. To perform hydraulic calculations using the HEC-RAS model, first the cross sections must be defined, for which the desired layer of the TIN map is extracted in the ArcMap software environment. After forming the TIN layer, different layers such as center flow line layer, river bank line layer, flow range layer and cross-section layer are drawn and after processing by ArcMap software, it is ready to be extracted for HEC-RAS hydraulic model work. The HEC-RAS model can perform water level profile calculations for Gradual variable steady flow in rivers and artificial canals in subcritical, supercritical and mixed flow regimes.
3- Results
The TIN layer is the basis for extracting the alignment lines and the required RAS layer, and the more accurate the obtained river elevation figure, the closer the 3D model will be to reality. In this study, due to the use of topographic map 1: 2000 and also the adaptation and casting of existing maps on the ETM satellite image of the region, it was found that TIN obtained from digital maps is able to significantly simulate floodplains and plains around Nooranchai River. The basis can be a good reference for conducting research and creating flood simulation layers of the Nooranchai River. The minimum altitude is 1220 meters and the maximum altitude is 1530 meters above sea level. According to the flood zoning map (Figure 11), the flood area with a return period of 2 years along the Nooranchai River is about 122 hectares. These zones mainly correspond to the bed of Nooranchai river, which locally surround the river channel. The average width of areas exposed to floods with a return period of 2 years is about 160. In general, such floods do not pose a threat to human communities living in urban and rural areas. Finally, the highest flood zone with a two-year return period covers the lower part of the Nooranchai River, which has entered the Ardabil plain, and the lowest flood zone with a two-year return period can be seen upstream of the Nooranchay River. However, these floods are of great importance in the formation and morphological changes of the Nooranchai River duct due to their high frequency and potential for shaping the channel platform. Also, the average flood width of 50-year-old floods is about 307 meters. These floods cover flood zones with return periods of 2, 5, 10 and 25 years. As a result of this increase in area and width in areas (3), (4), the areas leading to the Ardabil plain, which are lower than areas (1), (2), has led to more flood zones in the above areas This has caused the flooding of agricultural lands around the Nooranchai River, and even damaged some residential areas of Ardabil and the villages through which the Nooranchai River passes, and even resulted in casualties. In general, such floods can pose a threat to human communities living in urban and rural areas. Finally, the highest flood zone with a return period of 50 years is downstream of Nooranchai River, which flows through Ardabil, and the lowest flood zone with a return period of 50 years can be seen upstream of Nooranchay River. The impact of floods with a return period of 200 years along the Nooranchay River increases by about 329 hectares. Also, the average flood width of 200-year-old floods is about 500 meters. These floods cover flood zones with a return period of 2, 5, 10, 25, 50, 100 years. As a result of this increase in area and width, more can be seen in all parts of the upper, middle and lower reaches of the Nooranchai River. In other words, during the return period of 200 years, the flood zone of Nooranchai River has covered all parts of the river. Due to high discharge and the participation of discharges of different tributaries, such floods can affect a large part of the floodplain area of the river and in addition to human and financial losses and destruction of agricultural lands, have many morphological consequences such as shortcuts, and so on. Floods with a return period of more than 200 years affect the residential areas of the villages around the Nooranchai River and even the riverbed in the part entering the Ardabil plain; they can also affect part of the residential areas of Ardabil.
4- Discussion & Conclusions
Considering the flood simulation of Nooranchai river using HEC-RAS hydraulic model, it was concluded that it shows a very high spatial variability of flood risk along Nooranchai river. This variability stems from variable geomorphological conditions along the river. The results show that floods with a return period of 2 years do not pose a serious threat to human communities living in the vicinity of the Nooranchai River. These floods mainly affect the agricultural lands along the river. The risk of floods also increases with increasing return periods. Floods with a return period of 50 years due to the inclusion of a large area of the river and affecting residential areas will lead to property and human losses. These floods can also lead to morphological changes around the river, as well as extensive damage and loss of life and property. Rather similar findings were obtained by scholars such as Rad et al. (2018), who conducted a study in Khorramabad watershed located in Lorestan province and indices such as flow boundary conditions, maximum instantaneous flow with different return periods, cross sections and their distance and manning roughness coefficient for each section in HEC-hydraulic model RAS implementation and water level profile were obtained in different flood return periods. In addition, Shafiemotlagh & Ebadati (2021) used HEC-RAS software to zone the flood and simulate the hydraulic behavior of the Maroon River. They concluded that the flooding area for the return periods of 5, 10, 25 and 50 years is equal to 1265, 1651, 2334, 4450 hectares, respectively, and the number of endangered villages is equal to 5, 3, 2 and 9, respectively.
Rivers are considered as the main sources of water for humans and other organisms, and sometimes this source of life causes destruction and irreparable damage. Predicting the hydraulic behavior of rivers in the face of potential floods to reduce damage to urban and rural areas, facilities under construction, farms and other existing uses around the river is of particular importance (Askari et al., 2014) because they can be used to provide measures and solutions to control floods and minimize the damage caused by it. One of the key topics in geomorphology, engineering and river management is the morphology of river canals, which provides useful information about the geometric shape, bed shape, longitudinal profile, cross sections and their deformation and location over time (Yamani et al, 2012). ). Hejazi et al. (2020) zoned for flood risk in the Varkeshchay catchment using the HEC-RAS model. The results of these researchers showed that 110 km of the total catchment area is affected by floods with a return period of 50 years and 63 km of it is affected by floods with a return period of 25 years. Shafiei Motlagh and Ebadati (2020) used HEC-RAS software (Case study: Maroon River - southwest of Iran) to perform zoning of the flood and simulating the hydraulic behavior of the river. They concluded that the flood area for different return periods of 5, 10, 25 and 50 years is equal to 1265, 1651, 2334 and 4450 hectares, respectively, and the number of endangered villages is equal to 5, 3, 2 and 9, respectively. In a study aimed at producing flood risk maps in Kazakhstan, Ongdas et al. (2020) stated that the village of Volgo was flooded during a 100-year flood event. Aynalem (2020), in a study on the Muga River, reported floodplains for 5, 10, 25, 50, and 100-year return periods of 18, 21, 26, 34, and 43 km2, respectively. Therefore, the aim of the present study is to morphologically simulate the occurrence of floods in the Nooranchay River using the HEC-RAS hydraulic model.
.2- Methodology
Geological maps 1: 100000, topographic maps 1: 50000, and 1: 2000, data of synoptic stations, rain gauges, and flowmeters are among the most basic data of the present study which were prepared by Ardabil Regional Water Organization. HEC-RAS software or software river US Army Engineering is a set of tools that allows the user to perform river hydraulic calculations in steady-state and non-steady-state flow. The HEC-RAS system includes three components of one-dimensional hydraulic analysis to perform water level profile calculations in steady-state flow, non-steady-state simulation and sediment transport calculations at the moving boundary. These three components share a common geometric representation and use the same geometric and hydraulic calculation process is set of tools that can be used in the GIS software environment. This add-on creates a link between ArcGIS software and HEC-RAS software, and is specifically designed for spatial data processing for use in RAS modeling and for processing RAS results in the GIS environment. Processing ground data and other GIS data in ArcGIS software using GEO-RAS allows the user to create and export a geometric file for RAS analysis. To perform hydraulic calculations using the HEC-RAS model, first the cross sections must be defined, for which the desired layer of the TIN map is extracted in the ArcMap software environment. After forming the TIN layer, different layers such as center flow line layer, river bank line layer, flow range layer and cross-section layer are drawn and after processing by ArcMap software, it is ready to be extracted for HEC-RAS hydraulic model work. The HEC-RAS model can perform water level profile calculations for Gradual variable steady flow in rivers and artificial canals in subcritical, supercritical and mixed flow regimes.
3- Results
The TIN layer is the basis for extracting the alignment lines and the required RAS layer, and the more accurate the obtained river elevation figure, the closer the 3D model will be to reality. In this study, due to the use of topographic map 1: 2000 and also the adaptation and casting of existing maps on the ETM satellite image of the region, it was found that TIN obtained from digital maps is able to significantly simulate floodplains and plains around Nooranchai River. The basis can be a good reference for conducting research and creating flood simulation layers of the Nooranchai River. The minimum altitude is 1220 meters and the maximum altitude is 1530 meters above sea level. According to the flood zoning map (Figure 11), the flood area with a return period of 2 years along the Nooranchai River is about 122 hectares. These zones mainly correspond to the bed of Nooranchai river, which locally surround the river channel. The average width of areas exposed to floods with a return period of 2 years is about 160. In general, such floods do not pose a threat to human communities living in urban and rural areas. Finally, the highest flood zone with a two-year return period covers the lower part of the Nooranchai River, which has entered the Ardabil plain, and the lowest flood zone with a two-year return period can be seen upstream of the Nooranchay River. However, these floods are of great importance in the formation and morphological changes of the Nooranchai River duct due to their high frequency and potential for shaping the channel platform. Also, the average flood width of 50-year-old floods is about 307 meters. These floods cover flood zones with return periods of 2, 5, 10 and 25 years. As a result of this increase in area and width in areas (3), (4), the areas leading to the Ardabil plain, which are lower than areas (1), (2), has led to more flood zones in the above areas This has caused the flooding of agricultural lands around the Nooranchai River, and even damaged some residential areas of Ardabil and the villages through which the Nooranchai River passes, and even resulted in casualties. In general, such floods can pose a threat to human communities living in urban and rural areas. Finally, the highest flood zone with a return period of 50 years is downstream of Nooranchai River, which flows through Ardabil, and the lowest flood zone with a return period of 50 years can be seen upstream of Nooranchay River. The impact of floods with a return period of 200 years along the Nooranchay River increases by about 329 hectares. Also, the average flood width of 200-year-old floods is about 500 meters. These floods cover flood zones with a return period of 2, 5, 10, 25, 50, 100 years. As a result of this increase in area and width, more can be seen in all parts of the upper, middle and lower reaches of the Nooranchai River. In other words, during the return period of 200 years, the flood zone of Nooranchai River has covered all parts of the river. Due to high discharge and the participation of discharges of different tributaries, such floods can affect a large part of the floodplain area of the river and in addition to human and financial losses and destruction of agricultural lands, have many morphological consequences such as shortcuts, and so on. Floods with a return period of more than 200 years affect the residential areas of the villages around the Nooranchai River and even the riverbed in the part entering the Ardabil plain; they can also affect part of the residential areas of Ardabil.
4- Discussion & Conclusions
Considering the flood simulation of Nooranchai river using HEC-RAS hydraulic model, it was concluded that it shows a very high spatial variability of flood risk along Nooranchai river. This variability stems from variable geomorphological conditions along the river. The results show that floods with a return period of 2 years do not pose a serious threat to human communities living in the vicinity of the Nooranchai River. These floods mainly affect the agricultural lands along the river. The risk of floods also increases with increasing return periods. Floods with a return period of 50 years due to the inclusion of a large area of the river and affecting residential areas will lead to property and human losses. These floods can also lead to morphological changes around the river, as well as extensive damage and loss of life and property. Rather similar findings were obtained by scholars such as Rad et al. (2018), who conducted a study in Khorramabad watershed located in Lorestan province and indices such as flow boundary conditions, maximum instantaneous flow with different return periods, cross sections and their distance and manning roughness coefficient for each section in HEC-hydraulic model RAS implementation and water level profile were obtained in different flood return periods. In addition, Shafiemotlagh & Ebadati (2021) used HEC-RAS software to zone the flood and simulate the hydraulic behavior of the Maroon River. They concluded that the flooding area for the return periods of 5, 10, 25 and 50 years is equal to 1265, 1651, 2334, 4450 hectares, respectively, and the number of endangered villages is equal to 5, 3, 2 and 9, respectively.
Type of Study: Research |
Received: 2022/02/7 | Published: 2022/09/21
Received: 2022/02/7 | Published: 2022/09/21
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