Geography & Demographics

Geography, Climate & Demographics

Although Tehran is not Iran, but without this great metropolis, which is the focal point of Iran’s transportation network and the center in which more than 40% of the nation’s economic activities takes place, it would not be possible to fully comprehend the ever changing Iran. Tehran is the mirror of Iran. Those who inhabit this young metropolis have come from around the country with different beliefs, cultures, languages and life styles and live in a national and international context together. It can be noted that modern societies take form in large cities, and therefore, Iran’s future is being formed in Tehran.
Iran is a complicated and mysterious country and Tehran is more so. Activities, population and cultures have shaped a new and ever changing logic upon which people relate to one another without prior familiarity. This phenomenon, despite being problematic, expands and facilitates innovations and creativity.
Tehran Coordinates
Province: Tehran
Latitude : 35 40 N
Longitude: 51 26 E
City: 1500 km (579 sq. mi)
Urban: 686 km (265 sq. mi)
Elevation: 1200 m (3,900 ft.)
Population (2006): about 11,000,000
Density: 10000/km (25,899/sq. mi)
Time zone: +3.5 GMT
In fact, this is a characteristic of all metropolises to instigate new dynamism. Availability and awareness of economic, social and cultural information are necessary for understanding a city. These concepts, however, make sense only when they materialize within a country, an urban space or its periphery. Although the City of Tehran can be similar to Los Angeles or Shanghai in terms of urban planning, size, variety, internal dynamics and economic role, it cannot be understood without its territorial and cultural characteristic. Tehran’s population increased fifty folds from 200,000 in 1900 to10.3 million in 1996, of which 6.8 million live within the city limits of Tehran. In the same period, however, total population of Iran increased only five folds, from 9.8 million to 60 million. Tehran, which had only a 2% share in total population, now incorporates more than 15% share. This proportion has remained relatively stable since 1970s. This population explosion is the result of migrations due to the Capital’s unique attractions. A capital that was merely a town 100 years ago has now become a more or less modern metropolis, because of governmental Centralization and improvements in social welfare. Hence, Tehran, despite its many unique aspects, is comparable with large cities such as Ankara, Brasilia, and even St. Petersburg.
Tehran is located on the southern slopes of Alborz, and in approximately equal distance from eastern (Afghanistan) and western (Turkey, Iraq) borders, sitting on the ancient and famous City of Rey. Tabriz and Mashhad are respectively 550 and 750 kilometers away. Tehran is not far from Khazar (Caspian Sea) with an aerial distance of 100 kilometers. However Alborz and Emamzadeh Hashem passes, with an altitude of more than 2700 meters, must be overtaken on the way from Tehran to Mazandaran to reach the Sea. Isfahan, the capital during the Safavi dynasty, is 350 km to the south. Today, Iran’s Capital, although far from other big cities of the country, is located in an ancient strategic crossroads. On the one hand it is situated on the route from Anatolia (Turkey) to India and China along Alborz Mountains and on the other hand, at the intersection of roads that extend from southern parts of the country along Zagros Mountains (Persian Gulf, Shiraz, Isfahan) and from the west (Mesopotamia, Qasr-e Shirin, Kermanshah, Hamedan). Today, Tehran Metropolis is the most urbanized area between Istanbul and Karachi. These distinct elements, i.e. mountain, mountainside and desert, have formed the region’s landscape as well as its natural, social and cultural environment: from high to low, from cold to warm, and from summer resorts to winter resorts. Towns and villages are located on the mountainside between these two poles and human activities have followed suit.

Tehran is a mountainside city with an altitude of 900 to 1700 meters above the sea level. Its urban area spreads entirely over the Iranian plateau, on the slopes of a very high and dense mountain barrier, with a peak of 3933 m (better known as Towchal ) which is 2200 m higher than the City’s residential areas. From Qazvin to Varamin, the view is dominated by the Alborz Mountains, with rivers that are full in springtime and dry in summertime, flowing to satiate underground water tables hidden in the very thick layers of sedimentary rocks (gravel, sand and clay) from the Quaternary. Multiple aqueducts bring the water to surface that, in turn, flows through irrigation canals and brooks along all streets and avenues of Tehran and many other towns and cities within the province. Unlike Isfahan, no sizeable river passes through this province’s towns, other than Karaj. In higher parts of the slope, i.e. over 1500 m, it becomes cooler while major water resources in the area have provided for the development of big and arborous (mainly poplar and fruiters) villages. Lower parts, between 900 to 1200 m, have a fertile soil and a gentle slope that permit a productive agricultural activity. In these plains, there are many sources of surface or underground water tables, supplied by aqueducts, flood ways and branched out rivers.
In the south of Tehran and its suburbs, beyond the new airport, the desert begins. Dry and very hot weather in summer and sometimes very cold in winter, make this region seem hostile, although this open and bare space plays the role of a strategic reserve space for Tehran Metropolis and its 12 million inhabitants. From geographic, natural and human points of view the same desert is the negative of the mountain side and has no significant role in Tehran’s landscape and activities. Qom, with 800000 inhabitants, is closely related to Tehran. It is, however, separated from Tehran by the desert and belongs to a quite different geographic entity.
Tehran’s climatic condition has no significant negative impact on the City’s development and its inhabitants. The contrast between mountain and desert, and even between north and south of the City, prevents weather crises from taking shape in any part of the year. When heavy snow obstructs mountain roads, plains in the rim of the desert (Dasht-e Kavir) have often a mild sunny weather. When it is too hot in the desert, one can refuge in the mountain just a few kilometers away. The significant change of weather in different seasons is ultimately pleasing and allows a great variety of activities, either agricultural or recreational, to take place.
Tehran region has a dry climate. Unlike many other cities of the Middle-East, however, Tehran does not have an acute shortage of water supply. Although the annual rate of rainfall is only 229mm at the downtown, 400mm in northern neighborhoods and less then 150mm in arable lands of Varamin, heavy rainfalls in Alborz Mountains, mainly as snow, provide a fairly reliable source of water supply for Tehran’s residents and the City’s development.
Urban development has often relied on access to water sources. The wealthy have built their houses in higher elevations of the City in order to enjoy a cleaner and more copious water supply. This water flows through a number of rivers and flood canals toward the desert in the south and is swallowed up by the thick layers of alluvium. The traditional methods provide 20% of water mainly used for irrigating gardens, but the real source of Tehran’s water supply is a system of large dams built by Tehran’s Water Organization over Karaj River in 1956, over Jajrud River in 1968 and over Lar River in 1981. There is also a new dam under construction over Taleqan River.
Southern slopes of Alborz are dry (less than 500mm of rainfall in a year), while mountain tops and northern slopes are very humid and have an annual rainfall of more than 2000mm, mostly as snow. Thus, rivers are fed for a long time. Each valley of the southern slope defines the down stream town associated with it. Tehran, however, is an exception since no river passes through the City other than Kan floodway which is almost always dry. Eastward, Hableh rud River (with 225 million cubic meter of water per year) flows down Firuzkuh mountains and drains into Garmsar plain and the desert. This large and deep valley has always been an important route connecting the Iranian plateau and the Caspian sea, as evidenced by remnants belonging to Timurid, Safavid and Qajar eras. The old road of Safavid era is still being used by Iran’s railroad to pass over the Alborz Mountains, between Garmsar and Sari. Further west, is the small river of Kilan that irrigates Eyvanekey plain which is often dry in late summer. Jajrud (“the Furious River”, with 295/000/000m3 of water per year) flows down from Shemshak mountains, passes beyond Hezardarreh hills, east of Tehran, and irrigates the great arable plain of Varamin. Since 1970, most of its flow has been deviated toward Tehran to fill the water reservoir behind Latyan dam, causing the level of underground water sources in arable plains to drop. To solve this problem, Tehran’s sewage system is directed toward these lands.
Westward, Karaj river has the most copious flow in this region (535/000/000m3 of water per year). A diversion canal was built in 1860 to irrigate the gardens of northern Tehran in the Qajar era. This canal, known as “ab-e Karaj” is still there in now Keshavarz Blvd. Amir Kabir Dam is the first modern dam constructed in Iran over this river. Downstream arable lands of Karaj, between Shahriar and Eslamshahr, are one of the largest and richest agricultural zones of the Metropolis. Sometimes, floods of Karaj River reach the Grand Salt Lake (Daryacheh-e Namak) in the desert, north of Qom.
In the west of Tehran, Savojbolagh plain, between Karaj and Qazvin is not irrigated by any major river and only the small Kordan river flows through it. Taleqan and Alamut rivers flow through mountains westward and join to from Shahrud river, which joins with Qezel Uzen river to create Sefidrud River that irrigates Gilan’s plain, on the coasts of the Caspian sea. In Taleqan, in place of a small diversion dam built in 1970 to change the flow toward Qazvin’s plain, a big dam is now being constructed, to become operational in 2007. These new water resources provide for the development needs of Tehran Metropolis for at least the next two decades.
The main problem of Tehran in this regard is filtration of sewage. Since 1991, the project of constructing the main canals of the sewerage system for collection of the surface water has accelerated, although more work remains to be done. Tehran’s underground water tables are often contaminated by cesspools that exist in all buildings. Thus far, abundance and high quality of Tehran’s water supply had obviated the need for major investment in purification and recycling of water. Today, however, the only way to make sure that this metropolis can have a sustainable development is to think about water treatment and recycling.
The city of Tehran had a population of about 11 million people at the time of the last official census in 2006.
With its cosmopolitan air, Tehran houses diverse ethnic and linguistic groups from all over the country and represents the ethnic/linguistic composition of Iran (with a different percentage though). More than 60 percent of Tehranis were born outside Tehran.
Tehran is the largest Persian-speaking city in the world and Tehrani-spoken Persian is the standard spoken form of Persian language used throughout the country. Although indigenous people of Tehran before 19th century were Mazandaranis (Still residing in the southern slopes of Alburz), today the majority of Tehran residents are Persians who speak many different dialects of Persian corresponding to their hometown, including Esfahani, Shirazi, Yazdi, Khuzestani, Dari, Judeo-Persian, etc. The second largest linguistic group is that of the Azeri-speakers.
According to “Thomas Herbert”, Tehran’s fortification earlier surrounded a fairly small town with only 4.2 km2 area even though it had its 114 towers and 4 gates. In 1727 A.D., the City had a population of 3000 households, which was smaller than Kashan. However, it had a major marketplace (bazar) and good quality buildings that were used as temporary residence for kings and rulers who happened to pass through the City on their way to other regions of the country.
Tehran was reborn in 1759 A.D., when Karim Khan-e Zand arrived in Tehran and repaired the City’s fortification that was destroyed in Afghans invasion. He also built a palace in 1766 that became to be known as Golestan because he was planning to make Tehran the Capital of Iran. Tehran at that period, however, was at a crossroads for rival tribes of Zand and Qajar clans. Therefore, the Capital moved to the City of Shiraz during the Zand dynasty.
Tehran became Iran’s capital in 1786, when Agha Mohammad Khan Qajar had his coronation there. His successor, Fath Ali Shah Qajar (1797 – 1834) built palaces only within the royal citadel (Golestan Palace) and in northern quarters of the City, where later became the location of Qasr prison. In 1806, P.A Jaubert estimated Tehran’s population at 30000, and Ouseley in 1811 enumerated 300 mosques and schools in Tehran.
Ker Porter, however, argues that Tehran’s population was 10000 during summer and 70000 during winter because many escaped its unpleasant and dusty climate in summer to villages on Alborz mountain slopes in Shemiranat shahrestan. These seasonal migrations had major impacts on the city life until 1960 when the use of kerosene heaters made permanent residence in higher altitudes and greener parts of the City’s northern quarters possible. The constitutional Revolution (Mashrutiyat) in 1906, discovery of petroleum in 1908 and the First World War that led to the overthrow of Qajars in 1923 evolved the notion of citizenship profoundly. The new ideas accelerated the efforts and made Tehran a capital befitting a society involved in deep change
In 2004, the population of Tehran Metropolis passed beyond 12 million. This is a high figure but is not disproportionate with respect to the total population of Iran (15.6%). This proportion has remained nearly constant for the past 40 years. Tehran’s urban region, after a period of rapid growth between 1950 and 1970, similar to other metropolises of the world is now witnessing slow growth rate. Since 1976, other cities of Iran have had a faster growth rate than Tehran. Thus the proportion of Tehran’s urban region population to the total population, after its stability between 1930 and 1960 at around 25%, decreased from 30.4% in 1976 to 24.1% in 1996. In this sense, Tehran is neither disproportionate nor too large. It is a metropolis within scale of a country with 70 million inhabitants. Since 1976, and especially after 1986, development of Tehran Metropolis has been characterized by a rapid growth of its suburban areas that contain 30% of its now 12 million inhabitants. Therefore, Tehran’s urban region is geographically very different from 1970s, not only in terms of population (according to 1990 census, Karaj, Eslamshahr and Qarchak had 940000, 265000 and 138000 inhabitants, respectively) but also socially, culturally, economically and administratively.
According to “Thomas Herbert”, Tehran’s fortification earlier surrounded a fairly small town with only 4.2 km2 area even though it had its 114 towers and 4 gates. In 1727 A.D., the City had a population of 3000 households, which was smaller than Kashan. However, it had a major marketplace (bazar) and good quality buildings that were used as temporary residence for kings and rulers who happened to pass through the City on their way to other regions of the country.
Today, territorial divisions between rural and urban areas are more meaningless than before. There are villages with population of several thousand which cannot acquire the status of “cities”. This situation has caused some dehestan (rural cantons) to be considered as the most populous concentrations of the province. In the 1996 census, 7 cities had more than 100000 and 34 cities had more than 25000 inhabitants. Some dehestans could be considered as cities in terms of population, but do not have adequate facilities and services to be called cities. For example, Emamzadeh Abutaleb, near Robatkarim, has 125000 residents, or Mohammadabad, near Karaj, has a population 100000; yet both are considered as dehestans.
Distribution of population in the City of Tehran and its urban area is quite unbalanced because the province of Tehran has both vast rural areas in the desert regions with low population as well as very rich and well irrigated arable lands that include very populous large villages. Populated areas in old quarters of the City are in a clear contrast with industrial regions with nearly no residential population. Therefore, average population density in various regions is meaningless: average density of province is 5.3 persons per hectare (pph), while in the City of Tehran it is 92 pph and in the province without Tehran, it is only 1.9 pph.
Tehran is a capital with a low average density because it has vast areas which are unbuilt. Previously, cities and villages used to take from in groups. Scattered huts, houses or industries were rare. This manner of occupying lands had led to completely distinct urban and rural landscape identity. This distinction between the “city” and the “village” is still obvious, although they now have similar socio-geographic features in social, cultural and economic respects. Since the emergence of suburban settlement is a relatively new phenomenon, no suitable method is yet available to turn empty arable and barren lands into built-up ones. Arable and barren lands that surround Tehran have given this metropolis a very heterogeneous and unbalanced image. Differences are always striking between highly dense areas in the southern half of the City (with 412 pph in districts 10, 14 and 17, and an overall average density of 300 pph) and low density areas in northern quarters with 40-90 pph (Vanak 44, Zafaraniyeh 54, and Tajrish 63 pph).
Although southern quarters have a higher density, there is no real contrast between the City’s north and south. Rather a more complicated geographical situation has been shaped: the City center that previously had a higher population density is now facing a decrease in residential population and its density is now lower than the City average (Ferdowsi, 92 pph). Municipal districts 21 and 22, which are recent additions to Tehran’s limits, and are less populated, could be exceptional because the industrial zone between Tehran and Karaj as well as the vacant and afforested land are located within them.
The unbalanced distribution of population is also observable beyond Tehran’s borders as well. Between the less populous mountainous area to the north and the desert rim areas, with a population of less than one pph, to the south, population concentration is greater in the mountain’s base. Except the Varamin plain and specially in the southern part of Tehran, where agricultural activities have become marginal and where villages have become cities indeed, agricultural areas have remained very thinly populated (between 1-3 pph). Suburbs have often taken shape without a plan. They have developed on arable lands that are restricted by law to be used for building construction. Much of such land has turned into cities such as Qarchak (212 pph) or Akbarabad (825 pph). The situation in Eslamshahr (81 pph) or Karaj (49 pph) is better because their urban development was quickly brought under control.

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