All other Geographic fields of studies , Interdisciplinary
Fariba Karami; Maryam Bayati khatibi; Narges Rostami Homaiolia
Abstract
Introduction Flood is one of the natural hazards affecting rural areas around the world. International statistics confirm the fact that, during the last two or three decades, natural hazards like flood has occurred many times compared to the past; it has also caused various harmful effects on rural regions. ...
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Introduction Flood is one of the natural hazards affecting rural areas around the world. International statistics confirm the fact that, during the last two or three decades, natural hazards like flood has occurred many times compared to the past; it has also caused various harmful effects on rural regions. Due to having a close relationship with natural environment and a limited capacity to confront environmental threats, the rural societies and the related production activities have been exposed to natural destructive forces more than other societies. Since the East Azerbaijan Province is a submergible province in Iran and regarding the several-year experience obtained from the loss of life and property caused by floods, it seems necessary to change the attitudes from “exclusive focus on vulnerability reduction” to “increased resilience” against natural phenomena such as the occurrence of floods. Moreover, because Tabriz city and the surrounded villages have been exposed to the danger of floods from the past, the objective of the present study was to explore and clarify the rate of resilience of rural areas in the southeastern suburbs of Tabriz metropolis against floods.Data and methodsThe present survey was an applied descriptive-analytic research. Data collection was done using library and field studies and relying on a questionnaire distributed among families and Rurals heads. The validity of the questionnaire was determined by using the opinions of the experts in rural and natural disasters, indicators, and components through the collective wisdom of Delphi method; its reliability value was also calculated by Cronbach’s alpha as 0.86. The population included the settlements of 5 villages in the east and southeastern suburbs of Tabriz city. Out of 8554 households in the population, 370 households were selected as the sample of the study according to the Cochran formula. The Kolmogorov-Smirnov test was used to examine variable normality. Regarding the normality of the research variables, the one sample t-test, regression, and one-way ANOVA were used to explore the rate of resilience dimensions (economic, physical, institutional, social, and ecological) in the intended villages. Furthermore, path analysis was used to explore the impact of the five dimensions of resilience (independent variable) on the resilience rate of rural settlements (dependent variable).Results The results of the one sample t-test indicated that among the indicators (social, economic, institutional, physical, and ecological), the social (average=3.50), economic (average=3.33), physical (average=3.10), institutional (average=2.54), and ecological (average=1.98) indicators have the highest impact on rural houses, respectively. The results of ANOVA showed that regarding resilience rate against floods, there is a statistically significant different among the villages. The resilience rate against floods is higher in Leili Khan Rural (average=1.548); it is lower in Chavan village (average=1.373). Besides, the average resilience of the villages against floods is 14.7, which is lower compared to the theoretical average (15); the significance level was less than 0.000. Thus, the resilience status is lower than average in the studied villages which is not desirable. Exploring the impact of each resilience indicator on the durability of rural settlements by path analysis revealed that economic status (β coefficient=0.405) and ecological indicator (β coefficient=0.181) are of the highest and lowest share in the durability of rural settlements in southeastern suburbs of Tabriz city against floods.ConclusionThe results of the analyses show that among resilience dimensions, the social dimension is of the best status and the ecological dimension is of an unfavorable status. Altogether, among the five dimensions (economic, physical, institutional, social, and ecological), the most important factors affecting the resilience of the villages in southeastern suburbs of Tabriz city were identified. The most important items (factors) in the economic, social, institutional, physical, and ecological dimensions were respectively “dependence on a job”, “villagers’ participation in helping flood victims”, “village heads’ planning and tact”, “age of buildings”, and “geographical properties (topographic status, elevation slope, slope, etc.)”. According to the results, the following recommendations are presented. Interaction should be established in order to increase the economic, social, institutional, physical and ecological dimension so as to increase the resilience of Tabriz County. Plans should be set based on the conditions and deficiencies of each village so that they can endure against accidents and hazards. The residents’ awareness of the impact of cultural influence and social relationships on the reduction of vulnerability should be boosted. Moreover, increasing coordination and obliging the crisis management organizations, improving the institutional and organizational contexts, and creating a mutual relationship between local organizations and rural people to increase satisfaction and institutional resilience, especially in the studied villages, are of great importance.
Geomorphology
Masoumeh Rajabi; Shahram Roostaei; Mohsen Barzkar
Abstract
IntroductionThe concept of morphometry involves the measurement and numerical analysis of land surface, shape, dimensions and form of land. In relation to flooding, watershed morphometry includes quantitative indicators describing watershed physical characteristics that control the pattern and quantitative ...
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IntroductionThe concept of morphometry involves the measurement and numerical analysis of land surface, shape, dimensions and form of land. In relation to flooding, watershed morphometry includes quantitative indicators describing watershed physical characteristics that control the pattern and quantitative characteristics of floods such as amount, time of occurrence, delay time, and flow hydrograph. Unusual development of cities due to population growth and consequent land use change has caused disruption of hydrological balance and increased flooding of basins. The purpose of this study was to prioritize the sub-catchments of Zab River based on a novel combination of morphometric analysis and statistical correlation and zoning of flood potential under sub-catchments.Data and Methodto disregard for human and social sub-basins, which has a great impact on the hydrological processes of the catchment. Based on the validation results, the Shinabad and Sufian basins have the highest priority, and the new method of morphometric analysis and statistical correlation have considered them the highest priority for managers' attention.The elongation ratio helps to understand the hydrological characteristics of the drainage basin and ranges from 1 for circular basins to 0 for extended basins and its high values indicate the shape of the basin circle, high peak discharge and high flood potential. Is. The values of tensile strength in all sub basins are more than 0.5 and indicate high potential for flooding. Straller (1964) considers the circle ratio a quantitative measure for visualizing the shape of the basin. High values of this parameter indicate circular shape, high to medium ruggedness and low permeability in the basin, which causes peak discharge in less time. The ratio of the circular ratios under the Lavin Tea Basins is 0.17, Copar 0.19, and Zab Small 0.27, indicating relatively low flooding potential in this parameter. The amount of this parameter is 0.35 under Shinabad basin and 0.31 under Sufian basin which indicates their higher flood potential in this parameter (Table 7). The branching ratio is an important parameter affecting peak runoff hydrograph discharge with high values indicating high instantaneous discharge and flood event. The mountainous and steep areas have a split ratio of 3 to 4. Branching ratio values indicate low flooding potential except for Shinabad basin which shows this ratio of 6.19 and this ratio indicates high flood potential Results and DiscussionSince hydrological units are based on morphometric parameters to prioritize flood mapping, firstly, using channel networks and elevation curves, topographic maps of 1: 50000 and digital elevation data are analyzed. The boundaries of the hydrological units became. Then, because the catchment morphological parameters have different effects on soil erosion processes and runoff formation, prioritization of the sub-basins was done in a new way based on the difference of morphological parameters and statistical correlation analysis between them. Morphometric parameters were calculated for all sub-basins in GIS software. Then, statistical correlation of morphometric parameters was performed based on the t-Kendall method using SPSS software. Based on the correlation matrix we can analyze the relationship between the parameters and define the relative weight for each parameter without All twelve variables including circular elongation ratio, branching ratio, flow frequency, drainage density, drainage texture, compaction index, shape factor, mean slope, roughness ratio, roughness, and roughness number for all sub-basins are calculated in Table 2. The Kendall correlation coefficient was used to investigate the relationship between Validation results showed that the new method of morphometric analysis and statistical correlation did not perform well in prioritizing all sub-basins, but this method was accurate in identifying the most priority sub-basins (most acute conditions). The reason for this may be due to the lower performance of morphometric analysis and the characterization of waterways in low-slope catchments. Also, the precise reason for not estimating the priority of some sub-basins is due.ConclusionThe selected twelve parameters are directly related to runoff and flood potential. Therefore, high values of parameters have a direct relationship with runoff and flood potential due to their greater impact on the selected twelve parameters. Indicator (Cv) values for each sub-basin are obtained from averaging of 12 indices and accordingly sub-basins of Shinabad and Sufis with high flood potential, sub-basin with small potential and sub-basin zab basin. Copar and Lavin Tea have physiographic and morphometric characteristics of the sub-catchments have a great influence on flooding and hydrological behavior, it is possible to study the status and potential of flooding below the catchments. In this research, in order to potential of flooding, firstly, Zab sub-basins were prioritized based on the new method of morphometric analysis and statistical correlation. Based on this method, the results showed that the Shin abad and Sufi basins are the top priority for the implementation of management measures to ensure.
Geomorphology
Mousa Abedini; biuk fathalizadeh; Masomeh Rajabi
Abstract
Introduction
When a natural process threatens human life or property, it is called natural hazard. Disasters’ statistics have shown that their effects are, considerably, increasing all over the world. Most of such disasters originate from geomorphological events. In fact, natural disasters have ...
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Introduction
When a natural process threatens human life or property, it is called natural hazard. Disasters’ statistics have shown that their effects are, considerably, increasing all over the world. Most of such disasters originate from geomorphological events. In fact, natural disasters have been a global concern and most of them have mainly been geomorphological. Hence, developing countries, in particular, are deeply influenced by such disasters. One way of decreasing damages caused by natural disasters is identification of disaster-prone areas and prevention of their development in such areas relying on land use planning. In this research, geomorphological hazards of flood, landslide and neotectonics were investigated in Zonouzchay catchment. The catchment in an area of 323 square km has been located in political-administrative zone of Marand county.
Methodology
The aim of the present study is to evaluate geomorphological hazards in Zonouzchay catchment through preparing zoning maps of flood, landslide and neotectonics hazards. Digital evaluation model images of height (DEM), geological maps and sentinel satellite images are the most important data used in the present study. For preparation of flood and landslide hazards’ map in Zonouzchay catchment, ten variables and effective parameters on flooding and flood spreading were combined in GIS environment. These variables are considered for zoning flooding hazard factors such as height, slope, convexity of the land surface, valley depth, lithological units, drainage density, distance from the main streams, height of the runoff, use and vegetation. For zoning landslide occurrence risk, the above mentioned variables (except for stream height, drainage density and valley depth) were used along with the three variables of distance from fault, slope direction and rainfall. ANP model in GIS was used in order to combine effective variables on flooding risk and landslide in Zonouzchay catchment. Moreover, zoning relative neotecnic activities for the underlying area was conducted by using relative tectonic activity index (Al Hamdouni, et al, 2008). Relative tectonics activity index (Iat) is developed by combination of other indexes. The index classifies the perspectives in four classes of relative tectonic activities:
Class 1: too high tectonic activities with values 1 < S/n < 1.5
Class 2: high tectonic activities with values 1.5 < S/n < 2
Class 3: medium tectonic activities with values 2 < S/n < 2
Class 4: low tectonic activities with values S/n < 2.5
Results and Discussion
Zoning Relative Tectonic Activity
Results of Iat index-basedzoning indicate that neotectonic activities in Zonouzchay catchment are, generally, medium to relatively weak. Field observations also indicate that erosive processes (in spite of resistant formations) are predominate in the study area. Lack or rare dispersion of neotectonic landforms, retreat and destruction of mountain fronts and widening of the valleys are among the reasons, which show relative weakness of the active tectonic in Zonouzchay catchment. The main part of the morpho-tectonic landforms of the catchment is in line with Zonouz-Harzand fault. For most of the sub-catchments Iat values are in classes 3,4, which shows average to weak status of the relative active tectonic in the catchment.
Zoning Flood Event Risk
ANP model-based results indicate that from among the employed variables, slope, distance from river and land surface convexity are, relatively, the most important variables with coefficients 0.23, 0.19 and 0.16. Findings of the study indicate that about 4% of Zonouzchay catchment area is in too high risk class, 7.4% in high risk class, 8.3% in medium risk, 21.7% in too low risk class and 58.6% is in too low risk class. Almost all upstream parts of the study catchment are in low risk to high risk classes. In the middle parts of the study catchment, flood zones are mostly bounded to two main valleys of the catchment. Width of the valleys has increased in different periods and, consequently, flood plains have been formed in the basin of such valleys. Some parts of Miyab and New Harzand villages have been located in this geomorphologic position. In the downstream parts of the catchment, width of Zonouzchay has increased considerably and also the two main streams of the study catchment join each other in this part. Presence of low slope lands, low relative height, adjacency to the main rivers, lower values of convexity index, higher density of drainage and the valley depth are considered as the most important effective factors of this part of the catchment in terms of flood event.
Landslide Risk Zoning
According to the results of ANP model, the three variables of slope with coefficient of 0.24, lithology with coefficient of 0.22 and rainfall with coefficient of 0.16 have the key influence on landslide occurrence in the study area. Hence, about 16.6 % of the catchment area is in too low risk class, about 38.1% is in low risk class, about 23% is in medium risk class, 15.8% is in high risk class and finally 6.5% is in too high risk class. Spatial distribution of the risk classes indicates concentration of high risk and too high risk classes in the middle arts of the study catchment. This can be related to various factors. Maybe, the most important reason is related to presence of geological formations prone to landslide and appropriate slopes for occurrence of such geomorphological process. In fact, in the middle parts of the study area dominance of slope 10%-40% , presence of high alluvial terraces , also occurrence of Marens , conglomerate formulations with Maren interlayers and dispersion of Flysch type have provided appropriate conditions for landslide.
Conclusion
Results of geomorphological indexes indicate that considerable part of anomalies of this index are originated from lithological differences of the area. Moreover, active tectonic zoning of the area shows relative weakness of neotectonic processes and movement of the area’s faults along with dominance of erosive processes. Regarding flood occurrence risk, results of ANP model indicated that the variables of slope, distance from river and convexity of the land surface have higher importance in flooding. From flooding occurrence perspective, about 4% of Zonouzchay catchment is in too high risk class and 7.4% is in high risk class. The dangerous zones are accordant to valleys’ bed of the two main streams of the catchment and hence, some parts of the residents in these valleys are exposed to destructive floods. Finally, based on results of ANP model results, three variables of slope, lithology and rainfall have higher importance in probability of landslide occurrence in the study area. About 16% of Zonouzchay catchment is in high risk class, and 7% of it is in too high risk class of landslide. Landslide occurrence in the middle parts of the catchment is highly expected due to a set of conditions such as vulnerable slope and geological formations.
Geomorphology
Batoul Zeinali; Mahdei Aalijahan; fatemeh dashtbani; Rahim Fazeli
Abstract
Floods are one of the most destructive atmospheric hazards which push different communities all over the world to suffer from life and financial damages. The present research has the aim of detection of synoptic and hydrometeorology features of flood in Herochay. For this goal, the data from daily rainfall ...
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Floods are one of the most destructive atmospheric hazards which push different communities all over the world to suffer from life and financial damages. The present research has the aim of detection of synoptic and hydrometeorology features of flood in Herochay. For this goal, the data from daily rainfall of stations in Khalkhal, Khanghah, Arpachayi and Lamber and the data from Hydrometer station in River Kivichay was used to detect the rainfall and flood happened and for synoptic inspection of this phenomenon, the data from Sea level pressure, upper layers of atmosphere like Geopotential high, Omega, Orbital wind, Meridional wind and Relative humidity in levels of 500 to 1000 HPA was used. The obtained results show that presence of low-pressure system on the surface of ground, occurrence of blocking and located of the study area on the east of the trough on the upper levels, negativity of atmospheric eddies and omega on different levels with humid supply of Black Sea and Mediterranean sea on the levels of 500 to 700 HPA, Red sea and Persian Gulf and Oman Sea on the levels of 850 and Caspian Sea on the levels of 925 and 1000 HPA have prepared the conditions needed for generation of instability over the atmosphere of the studied area. The mentioned conditions have caused intense thunderstorm and increase of Herochay discharge and generation of flood in that region.
Jamshid Yarahmadi; Mohammadreza Nikjoo
Volume 16, Issue 39 , May 2012, , Pages 151-169
Abstract
The present work aims to assess the effects that landuse change has induced on the flood frequency regime. Study area covers upstream of Alavian Dam (250 km2) in the Sofi Chai basin. The torrential periods (in terms of flood event frequency and duration) has been carried out by comparing each daily discharge ...
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The present work aims to assess the effects that landuse change has induced on the flood frequency regime. Study area covers upstream of Alavian Dam (250 km2) in the Sofi Chai basin. The torrential periods (in terms of flood event frequency and duration) has been carried out by comparing each daily discharge with the base flood. Here, the base flood (flood with 2 years return period) was calculated from maximum annual discharge based on fitting various distribution models, and then the best fit model was chosen by considering RSS criteria. The results indicate that flood events and their duration tended to be abated on the last decade.
In this research, landuse/cover changes have been detected by interpretation of remotely sensed data based on object oriented method. The results indicated that the positive changes of crop patterns (overdeveloping of orchards as well as dry farming increasing) were occurred in the study basin.
HEC-HMS model was applied for simulation of rainfall-runoff process and assessment of the effects of landuse changes on the flood frequency. HEC-HMS simulated results based on corresponding CN derived from 2000 to 2005 satellite images show 36% abated of flood event respectively.
It should be noticed that the construction of a part of mechanical watershed management operations can reduce the flood events by reserving the surplus runoff.
Masood Goodarzi; Saeed Jahanbakhsh Asl; Majid Rezaee Banafsheh
Volume 16, Issue 37 , November 2011, , Pages 133-149
Abstract
Flood risk estimation is one of the most important subjects for hydrologists and other scientists. The main objective of flood risk estimation is to study the past events in order to foresee the future flood risk. There are various methods for flood risk estimation. Rainfall- runoff and empirical equations ...
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Flood risk estimation is one of the most important subjects for hydrologists and other scientists. The main objective of flood risk estimation is to study the past events in order to foresee the future flood risk. There are various methods for flood risk estimation. Rainfall- runoff and empirical equations are among the most used methods. In these methods, rainfall is the main parameter influencing flood mechanism. In this research, spatial distribution of rainfall pattern in Esfahan province is studied. Esfahan province with 10.5 million hectars of area has located in the central part of Iran with different topography, climate and ecological condition. Over 203 rain-guages located in the study area and its neibourhood were studied. The duration base of data record was 33 years. A total of 1654 storm events with less than 1 hour to 72 hours duration were considered, in which three index events, i.e. widespread and maximum events were used. The common methods of geostatistics, Krigging, Co-Krigging, IDW and TPSS were applied to interpolate the recorded points to non-observed ones. Among the studied interpolating methods, Krigging shows the best results, from which the Gussian and spherical models best fits to the observed points. In order to gain the best results, it is recommended to add the number of rainfall guage sites according to the World Meteorological Organization (WMO) standards. Also, we propose grouping the study area into homogeneous regions and studying DAD in each homogeneous region is advised.
