Geography and Environmental Sustainability
Year:2012 | Volume:1 | Issue:1|Papers Count:7

In this research, geometric configuration and temporal rate of subtropical high pressure was studied at the level of 500 hPa. This study has been done using daily data of geopotential height at 12 GMT in NCEP/NCAR database with spatial resolution of 2.5×2.5 degree in a 55 years period including 20089 days from Dey, 11th, 1329 to Dey, 10th, 1384. At First, the mean geopotential height at 12 GMT is extracted for all days of solar calendar to determine geometric configuration of subtropical high pressure and its relation to the contiguous patterns. Then, an agglomerative hierarchical cluster analysis on the basis of ward linkage method has been carried out using Matlab software. According to this analysis five circulation features in the north hemisphere have been recognized. To identify temporal rate of subtropical high pressure with the selection of a suitable framework, the mean of geopotential height at 500 hPa level has been calculated and standardized for each day of solar calendar from 1330 to 1383. Thus, a matrix of size 19724×1 was obtained which indicates positive and negative anomalies (strengthening and weakening of subtropical high pressure) in each day. Comparing the frequency of positive phase occurrence days with that of negative phase event days in the level under study showed that during recent 50 years the aggravation days of subtropical high pressure were definitely more than weakening days of this dynamic system. Applying contingency table method and calculating X2 statistic during statistical period (1330-1383) showed that occurrence of precipitation in about 3.1% of studied stations (33 out of 1066) is independent of the influence of subtropical high pressure. These stations mainly encompass south coast of Caspian sea and north west of Iran. According to this analysis, the occurrence of precipitation in 96.9% of studied stations (1033 out of 1066) are intensively under control of subtropical high pressure at the time of the predominance of this system over Iran.

Being in different geographical latitudes, the existence of a variety of uneven lands, and the entrance of diverse synoptic systems during the year are among the major factors affecting Iran’s climate. One of the main parameters which determine the climate of a region is temperature in degree-day, which is the average daily air temperature. We intend to calculate, depict, and analyze both the average monthly, seasonal, and annual cooling degree-day and the average monthly, seasonal and annual heating degree-day of the country through temperature thresholds of 25 degrees using Asfazary database. This database includes average daily temperature from 1962 till 2003 on cells with dimensions of 15*15 kilometers across the country. Therefore, average daily temperature in Asfazary database is an array with dimensions of 15992*7187 whose lines show time (day) and the columns place (cells equal to15*15 kilometers). The average daily temperature in database Asfzary array has dimensions of 7187 * 15 992 whose rows indicate the time (day) and the columns location (cell). by adding the average cooling and heating degree days up monthly energy plans were obtained. Then by adding seasonal energy balance we got the required seasonal energy map, and finally by accumulating the average annual energies the required annual energy balance was achieved. Results of the analysis of monthly mean maps of the country’s energy balance represent a macro-climatic zoning in Iran. In the warm half of year, the flat part needs a higher energy balance due to higher cooling. But in the second half of year the uneven part is in need of the most energy balance.

The study of runoff as a destructive phenomenon and meanwhile very important from the viewpoint of application is very useful. On the other hand, the recognition the area susceptible to produce flood and a program for its harness need a multi- dimensional study of the factors which effect flood. This study has been done on Dinevar River for the same reason. First the regional watering curve of Dinevar basin was drown using the annual maximum discharge of 10 hydrology stations to estimate the annual maximum discharge of four Dinevar sub-basins. Secondly, by overlaying of fourteen factors as information layers in GIS, the Dinevar basin has been divided to 5 zones containing the areas with high, relatively high, intermediate, relatively low and low classes. These layers efficient in the forming of runoffs were slope, litho logy, geomorphology, land use, hypsometer, slope aspect, the length of first grade flood channel in litho logy, the length of second grade flood channel in litho logy, the number of first grade flood channel in litho logy, the number of second grade flood channel in litho logy, the length of first grade flood channel in geomorphology, the length of second grade flood channel in geomorphology, the number of first grade flood channel in geomorphology, and the number of second grade flood channel in geomorphology. Result shows that although the slope and lito logy are important factors in Dinevar flood, the geomorphologic structure of Dinevar is the main reason of Dinevar River. In other words, the hogback structure with steepness and impermeable slope is the reason of Dinevar flood. This characteristic causes 35% of Dinevar land have high to relatively high talent and 50% intermediate talent in flood.

The wind erosion, digging the land, the transfer of materials, and cramming it in a different spot change the earth face. This study aims at examining the behavior of wind in sedimentation on the surfaces with different slopes in laboratory. To fulfill this an experiment was done in the laboratory in the form of a random pattern with 7 Tamaris including the slope of zero percentage, ±%2, ±%5, ±%10. The results of radiance analysis show a meaningful difference in the slopes less than %1 in sedimentation by tamaris. Comparing the average of tamaris by Duncan shows that the most sedimentation occurs in the surface without any slope so that with the growth of slope (direct and inverted) the sedimentation decreases. In order to express the relations between the percentage of sloping and sedimentation, the regression analysis has been used; it shows the decrease of sedimentation of wind as the slope of the surface grows. To examine the sedimentation of different slopes the model 2 was chosen, the others being the model 3 and the linear model. Finally, using the regression analysis, the relation between distance of tunnel exit and extent of sedimentation has been examined, which showed that the wind behavior and it’s function of sedimentation is different depending on the rate of slopes. Finally the process of sedimentation was specified for each surface by appropriate models: Including the linear model, model2, and model3 for the positive slope (direct) and the zero slope and model 2 for the negative slope (inverted). According to the results of this study, the laboratory simulation could be used as an appropriate method for studying the wind behavior in sedimentation on surfaces with various features.

Precipitation is one of the most complicated atmospheric elements having a lot of spatial and temporal variability. Specifying its characteristics and humidity sources, makes it possible to predict and understand this atmospheric element in a better and deeper way. The Red Sea trough is a surface low pressure which is extended over the Red Sea. This trough is usually associated with dry and warm weather. Simultaneous existence of a trough in middle level with surface trough can cause heavy precipitations and showery weather in east of Mediterranean and also in Iran. To verify the effect of the Red Sea trough on the precipitation of Iran, firstly the Iran precipitation data for a specific period (1/1/1340 to 10/10/1383 solar) were prepared. Secondly the Red sea trough for this period was also identified. Cluster analysis of the red sea trough showed that this trough has three main patterns. Then precipitation increment percent for each month of the year for every pattern of the Red sea trough was calculated and their maps were drawn too. This work was done for each day of the year as well.

Trips, as an inevitable part of the urban life, take place in various modes, each having its own special consequences on the urban space. For this reason the different modes taken by citizens can be assessed by urban planner carefully from different aspects. more sustainable trip mode, however, are encouraged by them to achieve more desirable urban environment which, in turn, would lead to sustainable cities. There are some main factors which affect trip modes, including urban spatial structure characters, individual and family characteristics, economic situation, and etc. This paper aims at investigating the effects of individual and spatial factors on trip mode choice of households in Babol as one the main cities in the north of Iran. The research question is finding out the spatial factors effects on trip modes in proportion to those of the individual factors.300 of households were surveyed using questionnaire which were delivered based on where samples live in three zones; inner (around CBD), middle and fringe zones. The results, obtained by multinomial regression analysis, show that both of these factors affect family’s trip mode choice to roughly the same extent.

The outbreak of rural migration takes place due to a wide range of socio-economic factors. Once the villagers, provided with better economic and social facilities, didn’t feel any reason to leave the villages, finding it as a suitable place for living. The goal of this study is, using the field study, to explore the probable changes in recent migration flows. To fulfill it, a number of villages of Bandar Anzali have been selected and studied via the questionnaire, and then the information was analyzed using SPSS. Findings show that factors once assuring the villagers’ residence at the village now have been evolved into the important factors for the migration from rural areas for the new generation. This problem together with the old factors will leave a double impression on unsustainability of rural society which could be called as "Intensive migration".