Ezatolla Ghanavati; Amir Saffari; Amir Karam; Esmail Najafi; Gholamhossein Jahandar
Volume 3, Issue 6 , January 2017, , Pages 33-54
Abstract
Ezatolla Ghanavati [1]* Amir Saffari [2] Amir Karam [3] Esmail Najafi [4] Gholamhossein Jahandar [5] Abstract Hydrogeomorphology is one of the branches of physical geography that studies the forms of roughnesses caused by the action of water in the environment. Investigationand understanding the ...
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Ezatolla Ghanavati [1]* Amir Saffari [2] Amir Karam [3] Esmail Najafi [4] Gholamhossein Jahandar [5] Abstract Hydrogeomorphology is one of the branches of physical geography that studies the forms of roughnesses caused by the action of water in the environment. Investigationand understanding the causes and characteristics of hydrogeomorphology and how to manage watershed areas within order to reduce the damage caused by flood events has more importance. This study aimed to investigate of hydrogeomorphologic characteristics of Tehran metropolis watersheds with emphasis on the flood prone zones through the assessment and review of watershed physiographic characteristics which dominate the metropolis of Tehran. Preparation and geomorphological mapping and map of the hydrological response units, flow charts drawn up for Hafthowz stations (Darake), Sooleghan (Kan), Poletajrish (Darband) and Qlak (Darabad) were done next. Extended aim of this study was to investigate the characteristics of the watershed of Tehran metropolis with an emphasis on flood through the assessment of watershed physiographic characteristics that dominate the area. Research approach was analytical- descriptive, using library studies, 1: 50,000 topographic maps and 1: 100000geological maps, 30 meter DEM of area, air photos of the year 1955 and satellite images of Google Earth and the utilization of ArcGIS, FreeHand, WMS and Excel were done. The results show that, due to the impact of watershed physiographic features including, watershed shape, area and low of drainages length, height and steep north-south difference that dominate the metropolis of Tehran, a small distance exists between the apex of watersheds and the receiving watersheds output and short duration of time of concentration and human interventions, and the urban runoff from rainfall in the study area. HRUS map of studied catchments represents the great diversity of hydrological response units most of the watersheds, especially the Kan watershed. The maximum instantaneous flow rate data charts, showed that Hafthowz and Qlak stations have a high variability due to the flood history in Tehran metropolis, due to their situation and hydrogeomorphologic properties of its upstream watershed which is heavily affected by flood events and that will be ordinary in Tehran region. Keywords: Hydrogeomorphologic characteristics, Tehran metropolis, Watersheds, Flood prone. [1]- Associate Professor, Faculty of Geographical Sciences, Kharazmi University, Tehran, Iran Emaiol:ezghanavati@yahoo.com. [2]- Associate Professor, Faculty of Geographical Sciences, Kharazmi University, Tehran, Iran. [3]- Associate Professor, Faculty of Geographical Sciences, Kharazmi University, Tehran, Iran. [4]- Ph.D. Candidate of Geomorphology, Faculty of Geographical Sciences, Kharazmi University, Tehran,Iran. [5]- Master of Urban Planning.
Amir Saffari; Mariyam Jan Ahmadi; Monireh Raeati Shavazi
Volume 2, Issue 3 , January 2017, , Pages 81-97
Abstract
Nowadays, one of the main problems that the societies encounter is discharging of the ground waters and the lack of suitable substitution for that. In Bushkan Plain vast use of agricultural lands has caused a drop in groundwater level. One of the suitable solutions to reduce this crisis is artificial ...
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Nowadays, one of the main problems that the societies encounter is discharging of the ground waters and the lack of suitable substitution for that. In Bushkan Plain vast use of agricultural lands has caused a drop in groundwater level. One of the suitable solutions to reduce this crisis is artificial feeding of groundwaters. To this end, the most important step in the floodwater spreading plan is suitable zonation for water spreading and forcing the water to penetrate into underground water tables. In this study, a hybrid AHP-Fuzzy method in Geographic Information Systems (GIS) and 8 parameters of the slope, alluvium thickness, electrical conductivity, geology, land use, drainage density, conductivity and altitude are used. First, these layers were converted to Fuzzy and then were evaluated using Analytical Hierarchy Process (AHP) and Expert Choice software. The values achieved in ARC GIS 10/2 on fuzzy layer were multiplied to Fuzzified layers by using Raster calculator and were combined with Fuzzy overlay command and the final maps were then prepared. The results show that gamma value of 0/9 has the best overlapping and eventually, the optimal gamma was found on 5 classes as high improper, improper, average, proper and high proper in the plain. 7/11 percent of the study area was calculated within high improper class, and 11/1 percent of the study area belonged to the high proper class. The southwestern parts of the plain, where pasturage density is low, are the best areas for flood spreading.
