Hydrogeomorphology
mohsen rezaei; maryam zare
Abstract
Among the types of environmental hazards, flood is one of the most destructive natural disasters that causes a lot of damages and injuries. Therefore, it is very important to identify the potential areas of flood risk to reduce the damages caused by it. Using morphometric indices and AHP and ANP methods, ...
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Among the types of environmental hazards, flood is one of the most destructive natural disasters that causes a lot of damages and injuries. Therefore, it is very important to identify the potential areas of flood risk to reduce the damages caused by it. Using morphometric indices and AHP and ANP methods, this research seeks to identify flood vulnerable areas in the sub-basins of the Kashf Roud watershed. For this purpose, 16 morphometric indices include: basin area, basin perimeter, waterway length, basin length, shape factor, branching ratio, drainage density, roundness ratio, elongation ratio, tissue ratio, waterway frequency, shape index, maintenance index. The watercourse, basin elevation, elevation ratio, and elevation number were extracted from the DEM of the region, and the flood risk of all sub-basins was determined using two methods, AHP and ANP, and classified into five flood classes: very high, high, medium, low, and very low. were classified The comparison results of AHP and ANP methods were evaluated using Spearman's correlation and checking the percentage of changes. Finally, it was found that the ANP method is more effective in preparing the flood map of the basin. According to the results of this method, 24.3% of the basins are in the very high flood class and 25.7% are in the high class, and in total, more than 50% of the basins are in the high and very high flood class.
yaser hoseini
Abstract
1-Introduction Flood is a natural phenomenon, which threatens the life and properties of a large number of people all over the world, yearly. Flood discharge, regarding water resource exploitation, flood control, construction of dams, basin management, and hydrologic studies, is of high importance in ...
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1-Introduction Flood is a natural phenomenon, which threatens the life and properties of a large number of people all over the world, yearly. Flood discharge, regarding water resource exploitation, flood control, construction of dams, basin management, and hydrologic studies, is of high importance in studies. Therefore, the accuracy of these studies and the safety of waterworks and water structures depend on the methods of studies to a large extent. It is impossible to manage water resources in basins without the accurate determination of the peak flood discharge. The advances in flood estimation techniques have made it possible to use rainfall-runoff models to assess the hydrographic properties of the flood in watersheds and decrease the risks of the flood. In studies on water resources, it is of high importance to determine the flood discharge of different basins. Studies of Dile and Srinivasan (2014) and Hoseini et al. (2017) showed that basin level and rainfall can be the most important factor in runoff flow. Consequently, proper simulation and modeling of flood runoff are the important parameters in flood management in the region. However, it is necessary to use new models to determine flood hydrograph parameters. So, this study aimed to determine the peak flood discharge of the Darrehrood basin using regression mode for return periods of 10, 25, 50, and 100 years. 2-Methodology Darrehrood basin is located in Northwest Iran. The basin is surrounded by mountains and is considered the main basin of Ardabil Province. It lies within 47°30' to 48°55' longitude and 37°45' to 39°42' latitude. Its area is approximately 12900 km2. Discharge data were collected from 16 hydrometric stations with a statistical period of 15 years during 2001-2015. Incomplete data related to stations were completed using statistical methods and considering the best statistical distribution of floods in the studied sub-basins, floods with different return periods were calculated then the physiographic characteristics of sub-basins that affect flood rate include: area, slope, shape factor, height average, concentration-time, and curve number achieved using ArcGIS and WMS (watershed modeling system). To evaluate the model, maximum error (ME), root mean square error (RMSE), relative percentage error (ε), mean absolute error (MAE), coefficient of determination (R2), Coefficient of residual mass (CRM), and model efficiency (EF) were used. 3-Results and Discussion The model calibration results showed that the simulated peak discharge and flow volume are in good correspondence with the observed values, so that, the lowest goodness of fit (R2) value in the return periods of 10, 25, 50, and 100 years were estimated to be 97, 96.6, 95.8 and 94.7 %, respectively. The results showed that the linear regression model with very good accuracy can predict the peak discharge in the sub-basins in Darrehrood using the physiographic parameters of the basin and with increasing the return period, the accuracy of the model is slightly reduced. Model evaluation indicators for the return period of 100 years include root mean square error (RMSE), relative percentage error (ε), mean absolute error (MAE), Coefficient of residual mass (CRM), and model efficiency (EF) were calculated 40.75, 52.12, 0.52, 0.92 and 0.62 respectively. Cross-validation diagrams showed that all models were partially underestimated and the scatter of points around the one by one axis was very suitable for the whole return periods. According to the paired t-test of the difference between predicted and actual values in different return periods in the level confidence of 1% are not significant. 4-Conclusions The results of this study show that the model has good accuracy for estimating floods in sub-basins of Ardabil province.
Morad Darabi; Hossein Malekinezhad; Ali talebi; masoumeh hidari
Abstract
1-Introduction Floods have historically been the most common, deadliest and most expensive hazards among natural hazards. The risk of flooding has increased over time, especially since countries have allowed changes in the land uses and land coves in floodplains and plains. In Iran, like the other ...
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1-Introduction Floods have historically been the most common, deadliest and most expensive hazards among natural hazards. The risk of flooding has increased over time, especially since countries have allowed changes in the land uses and land coves in floodplains and plains. In Iran, like the other flood-prone areas of the world, the severity of floods and the extent of their damages have increased dramatically in recent decades. Land use and vegetation play an important role in the production of runoff due to its effect on infiltration, erosion, evapotranspiration and transpiration. 2-Methodology Khorrambid watershed having an area of 88.7 km is a part of the Sivand Dam watershed. The average rainfall of this basin is 228 mm and it has a semi-arid climate in the view of Domarten. Khorrambid metropolitan basin consists of 12 smaller sub-basins in the study area with three main waterways named A, B and C that cross the city upstream of Khorrambid and pass through the city. In this study, the design, purpose, and efficiency amount of the flood and runoff output amount have been evaluated and finalized from the hydrographic network. The set of Management, Biological and Structural works carried out in the Khorrambid urban basin of the Sivand Dam Branches include: management excavation, piling, seeding, Dry working forage, Dry Stone Structures, rock and PVC mesh, rock and earth dams. Detailed studies and implementation of Khorrambid urban watershed was carried out in 1999 and the implementation of watershed management projects started in 2002 and by the end of 2010 about 33% of the projects were implemented in the study phase. At the same time, the evaluation process regarding the effect of these projects on flood and runoff control took place. This study aimed to evaluate the performance of projects (management, biological and structural) on the runoff and water resources in Khorrambid watershed in Fars province. In this study, first, the height of the dams, the length of the reservoir and the slope of the canals were measured under the basins where structural projects were carried out to determine the route of the new water movement. Then the new concentration time was calculated using the Branse-Williams method. In the next step, soil cover layer data such as the percentage of canopy cover, hydrological groups and vegetation status were obtained to determine the number of curves and maximum holding and infiltration potential in the soil. Then using SCS method and Hyfa software, modeling the flood volume and outflow runoff for sub-basin were estimated. 3- Results and Discussion By analyzing the results of statistical analysis of changes it can be said that there were many changes in all land use and land cover as well as the implementation of structural and biomechanical projects in the studied area. To investigate the effect of land use and structural changes on the hydrological regime of the studied basin, SCS method was utilized. This model was formulated using GIS techniques. The results showed that due to the increase in rangeland land use (from poor to good condition) and the construction of watershed structures, flooding in the area has decreased in case there were 24-hour rainfall. This amount of runoff reduction in the basin A and C was 41% and 72%, respectively. 4- Conclusions It is suggested that by evaluating the projects, if the performance of these projects could be evaluated in appropriate ways and from various technical and engineering aspects, the results would lead to finding the causes of the proposed operation failure and presenting appropriate solutions to address them. On the one hand, this could improve the quality of implementation of watershed management activities, on the other hand, it would increase operational efficiency, and the learnt lessons would enhance future plans. On the other hand, it is recommended that since watersheds are in fact considered as a natural-human system as well as a planning and work unit, comprehensive management of these watersheds is essential for achieving sustainable development goals. Watershed management is a complex process whose practical goals should be in line with the promotion of stakeholders` interests and stakeholders` engagement at all levels of planning and decision making. Integrated Watershed Management requires a flexible process that taking into account the challenges and constraints of the Watershed System, makes good use of its opportunities and potential conditions to ensure the social and economic well-being of its stakeholders while maintaining the security of water, food and environment in order to meet its goals of sustainable development.
Ezzatollah Ghanavati; Feridoun Babaee Agdam; Taher Hemmati; Masoud Rahimi
Volume 2, Issue 3 , January 2017, , Pages 121-135
Abstract
Khiav Chai basin is located in Ardabil province as the sub basin of Gharasou basin. The
main river of this basin is Khiav Chai basin originating from the Sabalan Mountain,
which after passing through the Moeil valley flows into Gharasou River. Since the
Meshkin Shahr city is located downstream of ...
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Khiav Chai basin is located in Ardabil province as the sub basin of Gharasou basin. The
main river of this basin is Khiav Chai basin originating from the Sabalan Mountain,
which after passing through the Moeil valley flows into Gharasou River. Since the
Meshkin Shahr city is located downstream of this basin and is facing the frequent
danger of flooding, there should be special attention to prevent the flooding risk in this
area. This study focuses on the zoning potential floods in Khiav Chai basin using the
Fuzzy logic. To achieve this end, 8 parameters are used in this study including
vegetation density, drainage density, distance from drainage, lithology, land use,
rainfall, altitude and slope. In this model, all the layers with raster format were uploaded
into the Arc GIS software. Then the layers were fuzzified according to their functions.
In the next step, using different Fuzzy model functions, the zoning of the flooding of the
basin was completed. The results showed that the valleys, thalwegs with concave
slopes, and downstream areas were the most effective watershed areas in preventing
flood hazards. The results of this research can help reduce the loss of life and property
in downstream residential parts in the area, and can also be used as a basis for further
studies in relation to natural hazards.
