GEOGRAPHICAL RESEARCH
Year:2007 | Volume:23 | Issue:3 (86)|Papers Count:8

At the present time, the improper land use change in the fringes of big cities and smaller urban areas of Iran has turned to a big challenge, which puts agricultural production at risk. This research was conducted in the framework of a research project sponsored by Soil and Water Research Institute of Iran. The aim was to acquire quantitative data on geographical distribution, potentialities and production capacity of soils of agricultural lands that were converted to urban uses on the fringes of six big cities of Iran, namely Tehran, Karaj, Tabriz, Ahwaz, Shiraz and Mashhad cities and their suburbs. The geographic extent of urban areas in 1955 was delimited on a photo-interpretation map which was produced by interpretation of air photos, obtained in the same year. Similarly, the limits of residential sprawl into agricultural areas between 1955 and 2001 were determined on a map that was produced by visual interpretation of satellite image of 2001. The information on geographical distribution and potentialities of soil resources were extracted from soil maps, produced by Soil and Water Research Institute of Iran. In areas where soil maps were not available, land class and soil production capacity were estimated based on knowledge of soil survey experts. Separate information layers, produced in this research, were integrated in the ARC/INFO environment. Data integration led to information extraction on the aerial extent of urban sprawl and the lost opportunities for agricultural production on the converted farmlands. The results are indicative of rapid conversion of agricultural lands to urban areas over the past five decades. Between 1955 and 2001, more than 2, 950 hectares (ha) of agricultural lands per year were converted to urban uses on the fringes of the six big cities of Iran and their suburbs. Population of these cities increased seven fold (except for Karaj city with a population increase of about 75 times), while their population density decreased about 67%, leading to an increase of more than 260% in per capita land in urban areas, during the same period. More breathing space for residents of urban areas was achieved to the price of lack of ability to produce 500, 000 tons of wheat that could be produced a year, on 136,000 ha lost farmlands, including 39,000 ha class-I land with soils having no limitation, 43, 000 ha class-II land with slight limitations; and 54, 000 ha class-III land with soils having moderate limitations for Irrigated agriculture.

The study area is located in the north -western slope of Sabalan and northern slope of Gushe Dagh (38o 15' -38o 30' N, 47o 00' – 47o 38' E). This region, is mainly formed of new volcanoic rocks. Bedrock is generally covered by coarse regolith, debris and colluvials. The accumulation areas of large debris flows and forms large debris fans (up to several meters in diameter) on bedrocks, show that this bedrocks are suitable to the derived debris. As a result of suitability of these rocks to forms of debris, associated with favorable climatic condition and present of snow patch most of time, debris flow of the study area is active. The debris situated often in valleys and located in the course of 2 and 3 order streams. These debris, gradually by different factors, for example, the occurrence of flood, moving and transporting by streams and rivers to long distances.The debris deposition on foot of valley wall is a reason for changing of the river flow pattern and then a cause for cut off of valley in other side of valley. The debris flows in study area, have special characteristics, because of existence of topographical factors and morphogenesis. The length of debris flows in the study area is longer than its width. This rate in difference of altitudes is 1: 3 to 1: 5. This ratio in old debris flows is great and in present debris flows, is small. The results of statistical analysis show that, the role of the depth of channels, in the growth of the length of debris cones is remarkable.

As a result of inefficiency of the comprehensive pattern of urban developmental plans, a kind of systematic and strategic planning became prevalent in the west which investing acts the process of providing the "urban developmental plans" in the frame of "Analysis, Plan, and Domination". In this study, the attempt is to make an analytic comparison between the first urban guide plan of Mehriz and the present situation of the revised urban guide plan and then, to analyze and investigate the fulfillment of this plan regarding to population, physical and urban per capita aspects. The research method is descriptive - analytic. the findings show that the population fulfillment has been 72 percent so that not only we won't have the predicted population until the plan limits but it will also be about 664 individuals less than the present situation of the first plan.Physical and spatial development of the city have been fulfilled more than 100 percent and the calculations done on the basis of Holdern method indicate that the city has had an extreme extension so that in the future 26 years, the city limits will have enough land to attract population. The fulfillment of the urban efficiencies, except those related to green space, storehouses and transportation which are facing lack of enough space, has been over 15 percent. Not reaching the fulfillment of the predicted population, incorrect estimation of the per capita indices, inattention to the role and position of the city in the province and area and lack of pre- dominant plans have had negative effects on the appropriate fulfillment of the urban guide plan.

Soil temperature is one of the main physical parameters of soil. Plant growth and soil generation processes are subject to temperature changes. The study of soil temperature in different depth is of utmost importance in meteorology specially, in micro scale, in climatology, agriculture and industry. Soil temperature change is subject to weather temperature of earth surface. Relationship of soil and weather temperature is one of the most important relationships which can be applied in forecasting cold weather and estimation of damages incurred on agricultural products. Boroujen area is one of agricultural areas of chaharmahal province. This study has been in this area for decreasing the frost bite damages incurred on farmer's products of that area and proper information providing for them. In this study, the minimum weather temperature, minimum earth surface temperature and the temperature of different depths of earth (5-10-20-30-50 and 100 cm of earth) have been analyzed in definite standard hours, 6: 30 in the morning, 12: 30 of noon, and 6: 30 in the afternoon after collecting the data and doing different tests (data qualification and homogeneity). Observations show that the temperature changes range in 24 hours is decreased as the earth depth is increased and that a time delay is occurred in lower depths before the temperature reaches its maximum point. The annual temperature cycle shows a time delay and a temperature changes range decrease by depth increase. The annual average temperature of earth is more than the annual average temperature of air because the energy absorbed in earth is more then the energy absorbed in air and a part of heating energy absorbed in earth is transferred to lower depths. The depth of a frost bitten layer of earth has been determined in different seasons especially in the spring and fall and finally the predication of earth minimum temperature has been offered for the prognosis of the occurrence of these phenomena. The study shows that the reason of sudden temperature decrease in the spring has mainly been radiation temperature decrease. The temperature change of earth in 50 cm. depth has been slow in such a way that the total temperature changes have been about 19.3oC. The most temperature changes range in this area has been in 5 cm.depth and about 29.1oC. This study has shown that the correlation of the minimum weather temperature and minimum earth temperature in all months is linear. The most correlation has been 0.98 in June and the least correlation has been 0.52 in May. The change of earth temperature has been wavy and has been decreased from surface to depth. The maximum temperature has been in 50 cm depth of earth in August with one month delay.

The present research has been carried out to test the relationship between migration and population growth in Sabzevar with change and imbalance of labour market in this city and rural settlements of province during the last decades. In this research which is a causal-historical one, the migration rate and population growth in this city during (1956-1996), have been analyzed using labur market account through comparing the changes of the labour market in the city and rural settlements. The result of this research indicates that the population growth in Sabzevar during the late decades results from of rural Steelers to the city. This migration rate during the different periods has had positive and direct relationship with the qualitative and quantitative imbalance in the city labour market and rural settlement. It means that every period in which this city has had job surplus and its rural areas have had more job shortage, the rate of immigrants to city and emigrants of villages have been very high. According to the qualitative aspects of labour market, the result shows that the economical growth in this city and its attractions for the rural migration are indebted to the service activities and the industrial jobs has played a little role in the labour markets of the city.

Houses that their effective floor area are between 50m to 70m and constructed in large volume for poor people are called social housing. Social housing politics in Iran started since second development plan (1994-1998). In that plan, construction of 250, 000 house predicted and included the Kohgiluyeh va boyerahmad province in southwest of Iran. In this paper, social housing in Yasoug city is discuses. The main objective of this paper is to propose the influential factors on social housing demand in Yasouj city. This research applied a survey method. The data are gathered through a questionnaire. Statistic community of the research is consisting of 200 house-holds simple random method. In the analysis that selected by of the data, the statistical procedures used were chi-square, one sample T-test, Friedman test, and Kruskal-wallis test in 95 percent confidence interval. The result shows that economic factors are the most important element, that influencing social housing demand in Yasouj city.

A landslide occurred in 16.3.1384, in the way of Ardabil- Tabrize in Saien defile. One person died due to fall of his automobile and several machines damaged and more heavy damages occurred in the road. Effective factors to make this landslide were: gradient of the slope (more than 35 degree), spring rains some days before landslide occurrence (from the first day of Farvardin 1384 until sixteenth of Khordad 150mm rainfall occurred, that some of this rain infiltrated into the soil and increased liquefaction of soil.Intense weathering of earth surface materials (more than 5 meter depth), permeable and relatively thick soil (.5- 1.5 meter). In the surface of earth, excess of saturation capacity superficial formation (on the average 53 percent), surplus of plastic limit (26.30 percent) and liquid limit (34.92 percent) under surface formations such as: volcanic tuffs and other volcanic rocks that to make difficult infiltration of water in the depth of earth prepare the way for occurrence landslide. Along with the landslide, some of geomorphic phenomena occurred that we can present them such as: landslide escarpment, landslide cup, lake of landslide and etc. Reconstruction operations by Ardabil province's road and transportation office led to change in the geomorphologic landscape, and sometimes had led to morphogenesis. In this study, we will try to study the beneficial factors in landslide occurrence in 16.3.1384 and its geomorphic results.