Journal of Spatial Analysis

Illegal sale of extra building density (footages) and building violations all are being considered as the most important measures regarding urban management rent issues in Tehran, between 1991-2001. This in turn, intensifies the occurrence of building violations and instability regarding to Tehran’s spatial organization during the mentioned decade. This study aims to investigate the type, rate and spatial distribution of building violations and spatial-physical changes in districts of Tehran metropolis. The objective of this paper is to identify and explain the types of urban management functions and their resulting consequences in Tehran metropolis. The distribution pattern of building violations and some of their impacts are the major outcome of this research. This research based on its objective, possesses applied nature at strategic level. This study is based on spatial-structural and analytical approach. The under study area are all constructions in 22 districts of Tehran metropolis. It further supports the application of documentation. Data analysis demands descriptive statistic as well as GIS technique. This study suggests that 59% of all the issued construction permissions are associated with zone 1-5 followed by 67% which pertains to zones 1-7 between 1993-2002. These northern zones possess large holdings, good location, comparative advantage and very beneficial vertical density. About 117028 building licenses contain extra building footage problems. Total area of these violations occurrences has been amounted up to 32710210 meters. The distribution of the extra building footages associated with different zones represents a sharp but regular gradient with north-south direction. Moreover, this study suggests most of the governmental institutions committed violations associated with illegal land possessions as well as construction of illegal land uses in the area of public lands during 1990 decade. In addition, 249 illegal constructions pertaining to public institutions were identified by 2002 out of which 137 (55%) were visited by Tehran's municipalities.

     The statistics associated with Tehran's building violations which referred to variance number 1 of 100 municipality law represents a high magnitude and level of violations occurrence during 2000 decade. The total area deal with these building violations inspected by these commissions has been amounted to be 2810559 and 1565644 square meters in 2001 and 2008 respectively. However, some of these types of violations informally resolved without ever referred to this corresponding municipality commissions. Most of these violations are associated with land use changes (56.98%). This is followed by violations pertaining to extra density footages. It is argued that 3.5 violation cases registered against each issued construction license between 1997-2008 in Tehran metropolis. Generally, the issuances of building permits and sale of extra construction density and footages were dealt with market demand and geared toward gaining its resulting rents. These measures and actions were contradicted with Tehran's master plan principles. These violations possess a sharp gradient with north-south directions in Tehran's south and north economic-social basins. These activities are harmful to public interests and simultaneously very beneficial to very small inclusive private group which possess capital and lands. This in turn, is associated with lack of a master plan and subsequent spatial equalization, imbalanced land uses per capita and services and cons equally. Tehran's unsustainable physical development, For instance, Tehran's residential per capita in 1991, 1996, and 2001 has been amounted to be 20.35, 22.51 and 23.88 square meters respectively. This amount is associated with 17.37% growth rate unit during 1990 decade. However, Tehran's residential per capita in 1996 and 2001 have been underestimated and amounted to be 17.8 and 12.8% respectively compared with 1995 estimation (27.39 square meters). Tehran's existing commercial per capita in 2001 (2.05 square meters) compared with previous estimation of 1996 (0.87 square meters) shows 136.44% growth. This has been resulted from change in existing residential unit in central part of Tehran. Tehran's military per capita land use in 2001 (7.50 square meters) compared with the previous estimation of 2006 (1.5 square meters) shows 400.87% growth as well.

Tectonic geomorphology is part of Earth Sciences, which deal with study of the interaction of tectonic and geomorphology. In other words it studies the effective tectonic processes in forming and changing the landforms. Geomorphic and morphometric indicators are suitable tools to the morphotectonic analysis for different areas. These indicators are used as the base tool to identify and recognition of tectonic deformation or estimates of the relative instability of tectonic activity in a particular region. Some of geomorphic indicators has been widely used, then the results of research projects are used to obtain comprehensive information about active tectonics. Full assessment of contemporary tectonics and tectonic activities, especially the young tectonic and its hazards need to Full understanding of geomorphologic processes speed and made for this purpose, geomorphological methods play an important role in this context.

     This research uses a descriptive-analytical approach, using library studies and aims at determininge the activity of Neotectonic in 7 Watersheds of Tehran metropolis (from west to east: Kan, Vesk, Farahzad, Darakeh, Velenjak, Darband and Darabad). In the first step, using topographic and geological maps of  under the studied area, faults, drainage networks and watersheds are identified, then to evaluation  the indicators of Mountain Front sinuosity (Smf), the main river sinuosity (S), the drainage watershed asymmetry (Af), rivers density index (D), hypsometric integral (HI), the ratio of the watershed shape (BS), the ratio of valley floor width to valley height (Vf), river longitudinal gradient index (SL) and Index active Tectonic(IAT) have been determined. Survey of these indicators by topographic and geologic maps and Google Earth images of the under studied area using software of Google Earth, Arc GIS and Global Mapper are derived and calculated. In the following, parameters and how they are calculated are given:

-Mountain Front sinuosity is the result from equation (1):

Smf = Lmf / Ls     (1)

In the equation (1), Smf is index of sinuosity Mountain Front. Lmf is the front along the foothills and mountains of the specified slope failure and Ls: straight line along the front of the mountain.

- The main river sinuosity index is as follows: S = C / V.  In this formula, S is main river sinuosity.  C: along of the river. V: valley along of the straight line.

- Rivers density index, drainage density is obtained from the formula:

                            µ=  

Li is length in kilometers of drainage Watershed, A is area in square kilometers, μ is total drainage watershed in terms of kilometers per square kilometer.

- Hypsometric integral is an indicator which represents the distribution of surface heights variation from equation (2) is obtained:

HI= H - Hmin / H max – H min    (2)

In this equation Hi is hypsometric integral, Hmin and Hmax respectively are the minimum and maximum height and H is the height of watershed.

- The ratio of width to height of the valley floor is another geomorphologic parameters to investigate the tectonic forces in the region .This index is obtained from the equation (3):

VF =      (3)

VF, represents the relationship of the valley floor width to valley height, VFW: the valley, Eld and Erd to the height of the left and right and Esc is valley floor elevation valley.

- The ratio of the area ratio of the area and the equation (4) is obtained:

BS= Bl / BW      (4)

-BS; the shape of the watershed; Bl; length dividers watershed of water to the bottom of the watershed outlet and BW:  width of the flat portion of the watershed.

-The longitudinal gradient index (SL) for a range of drainage path is calculated and determined by the relationship: SL = (ΔH / Δ L) * L. In this regard, SL: the longitudinal gradient index, ΔH: height difference between two points measured, ΔL: during the interval and L: total length of the specified channel to assess where the index to the highest point of the canal.

The classification provided for indicators Sl, Smf, Vf, Bs, Af by Homduni et al (2008), this indicator is obtained based on the amount of 1, 2, 3 classified in three classes. Index of active tectonic (Iat) Geomorphic indicators by means of different classes Calculated based on the value of (S /n) is divided into four classes, That the division are characterized by class 1 with very high activity Neotectonic, Class 2 with high Neotectonic activity, Class 3 with medium Neotectonic activities and and Class 4 with low Neotectonic activity. In this classification of Class1 have the highest and Class 3 have the lowest Neotectonic activities (Table11).

On the basis of Iat indicator Neotectonic activities in the under studied area were assessment and results were is in table (13). Based on the data in Table (13) , watersheds of Kan and Darband hava a high Neotectonic activities and located in Class 2 and watersheds of Vesk, Frahzad, Darakeh, Velenjak and Darabad  have a medium Neotectonics activities and and located in Class 2, and Neotectonic activities are a high relative tectonic activity in all watersheds. Geomorphic indicators are reflecting activities in the metropolitan Tehran watersheds can say that tectonically active watershed has not yet reached stability and tectonic activity are relatively high. Geomorphologic indicators drainage watershed asymmetry, the main river sinuosity, the valley floor width to height ratio of density of rivers and valleys, structural geology and tectonic activity in the7watersheds of Tehran metropolis better show it.

The results show that Tehran metropolis Watersheds have a high relative tectonic activity in all watersheds, because of the proximity to the major faults (such as Mosha- Fasham and North Tehran faults) and minor faults, tectonic activity exists. Finally it can be stated that, due to the presence of multiple faults and background seismicity and tectonic activity in Tehran metropolis and its watersheds, occurrence of earthquakes in the study area is not unexpected and this issue requires serious consideration and management.