عنوان مقاله [English]
Phenomenologists believe that in nature there is a dual structure that depends on each other intrinsically, one is a structure that is objectively visible to any observer, and second the complex and interconnected structures that are not exposed to tangible objectivity. Geomorphology, based on the phenomenological view, also tries to understand non-tangible structures.Damavand Peak is a Quaternary volcanic phenomenon with an altitude of 5671 meters in the middle of Alborz sedimentary ridge. This phenomenon has changed the overall structure of the region and imposed certain changes on the whole Alborz region. Damavand has a different structure compared to other volcanoes, such as Sahand, Bazman and Kilimanjaro, and does not follow the radial form. It has the shape of the Owl's Eye . The main goal in this paper, is to clear the effects of structure on the behavior of the Haraz River and emphasize to spatial memory, energy distribution pattern and the changes of river flow.
Materials and Methods
The variables used in this research are mostly those of defining the structural pattern of the region. These variables are classified into three groups, linear, point and superficial, often defining-geometric patterns are considered in geomorphology. The variables analyzed here are i) the linear variables comprising fault lines, drainage networks, ii) the surface variables including the erosional surfaces along the Hazard River and iii) the points variables constituting the villages and peaks. All analyzes are based on satellite images and 30-meter DEM of Iran and the accuracy of these analyzes has been checked with field visiting (15 times). All of these information is presented in the framework of the phenomenological method, relying on the chaos theory, and the concepts of behavior geomorphology.
Discussion and results
The special structure of Damavand and its activity, have been reflected on structure of region, behavior of Haraz River, capture river, and defined a new space identity.
How Damavand has changed the structure of region
A: Changes in the fault systems
Generally, structural patterns in the Alborz region have been influenced by fault activity. Damavand volcano as a new plutonic activity has changed the tectonic structure and plays a decisive role in structure of this region. Comparing the tectonic structure of region (without volcano's activity) with the current structure (after volcano's activity) revealed the new structure created by Damavand is considered as a turbulence in the general structure.
B: Expand area of Haraz River basin
As shown in figure (3), there are three fault systems in the area. By evaluating and measuring the northern fault systems, the length of all this fault was 15 to 45 km, except that of Haraz with length reaching to 104 Km . This indicates that Damavand's activities have caused such a change in the area of draining basin.
In other words, the Haraz River basin was much smaller, and after the volcanic activity its basin has increased sharply and all branches of the river that have already flown south (Tehran) have been redirected to the north.
C: change the pattern of draining system
Investigating the drainage network in the area shows that the structure of the drainage network in Damavand has different patterns with other adjoining areas. As you can see, there are two distinct patterns in this area, one dendritic pattern and another spiral pattern . Changing draining patterns with Damavand volcanic activity is routine, but the Damavan rotational form is a special feature that separates it from other volcanoes such as Kilimanjaro, Bazman and Sahand. Because almost all of them have a radial form and Damavand has a structure Owl's eye model with a clockwise movement. This form has caused many processes to change and has had important effects on the distribution of energy and matter, especially in the Haraz River.
D: How Damavand have changed behavior of Haraz River
The sediments of these lakes now are at higher elevation than the current level of rivers in the areas of Nandel, Baijan, Gazeneh, Lasem and Lar. The excavation started in the Lagos valley from mid-December 2017, confirming the depth of sediment, more than 100 meters, and this indicating the depth of the lakes. This process has made the river function as a continuous and normal flow is converted into a cascade stream
E: change the space identity
After overflow and breaking the lakes, along the banks of the rivers, sedimentary beds have been leftover and created numerous villages on them. This phenomenon in Iran means the change of space identity, because in the mountains of Iran, villages take their space identity from the Water-Ice Equilibrium line (WIEL).
If we call geomorphology as a knowledge of land forms and analysis of patterns, we can claim that the Damavand volcano is different from the other volcanoes like Kilimanjaro, Sahand, Sabalan, and Bazman, and this difference is related to its chaotic structure. Damavand volcano have been affected on the environmental processes, such as the distribution of energy, matter and Haraz river behavior, and the main aim of this paper is to explain this. Although the patterns of the formal structure in Albourz Mountain are more influenced by the faults, the structure of the Damavand formative have completely confused the tectonic structures and changed the rule of formative system and behavior of Haraz River. The influence of structure in a variety of dimensions, such as the distribution of energy and matter on the region, river capture and river behavior, river basin expanding and sequences sediment has been able to create general space identity of this region. This article is the result of a studying in sabbatical leave at the University of Wurzburg based on the principles of phenomenology and the results is obtained show that:
*The Damavand form has followed the structure of the Owl's eye model and created a land-cyclone.
*Damavand has changed the patterns of distribution of energy and matter in this region, created a river capture and expanded the Haraz river network.
*The structure of the owl's eye of Damavand Has been created a special space identity in this region.
Key words: chaos theory, Structuralism, Spatial identity, Haraz River, Damavand cone