GEOGRAPHICAL RESEARCH QUARTERLY
Year:2008 | Volume:40 | Issue:64|Papers Count:14

A great part of Iran's area, especially Yazd province is formed as deserted areas. Kavir Siahkooh is one of the most important desert areas of province. The researches show that the arid areas have an ideal condition for remote sensing and it can consider and show the plant coverage of the area .The aim of this study is to evaluate Kavir Siahkooh plant coverage and its comprise with the data received from remote sensing. Data used in this research are TM, ETM+ Landsat satellite on the dates September 1990 and 2000. With the use of vegetation index (NDVI) on two series of satellite data kinds of plants and area are determined. The method of this research is correlation and comparison. The interpretations of data are done through computer, S.P.S.S software and IDRISI. The results show that kavir area is not changed in the period of ten years and the best vegetation index is NDVI Index for the study area. Regarding the importance of remote sensing and it application, it is proposed to use the satellite data especially from the images of high resolution and up to date for area of study. Secondly it is proposed that this area Investigate for purposes of soil moisture, salinity and salty crust with remote sensing data.

With due attention to importance of climate change and natural ecosystem sensibility of the study area, in this research have been studied the probable climatic departure from normal and the existence of trend in climatic time series is detected by statistical tests. The first on the basis of rank- method Mann Kendal, it is tried to identify of changes and then recognize their type and time. The results which are provided of data analysis by this method show that the most changes started as abrupt and it is known that these changes belonged to both type of trend and oscillation. The minimum temperature shows a positive trend and the maximum temperature shows a negative trend in the most of selected stations. Therefore, it seems the range of temperature has reduced during the study period. Also, the percentage of changes on winter and summer has been more than spring and autumn situation. Eventually, there aren't any coincident between the selected stations for purposes of changes beginning.

Studying the various issues related to dam- building projects is of high importance, and the results derived from these increase the success rate in performing such projects. Studies concerning erosion and sedimentation in the watershed catchments are among those issues. Ilam Dam is located on the konjancham area and the Amir- Ababd diversion Dam is under construction on the konjancham River, this research then has evaluated the erosion and the sedimentation in the given area from the qualitative and quantitative points of view by using the MPSIAC method in the GIS environment. To do so, after entering the data layers into the GIS environment and combining these layers, area was divided into 336 sedimentation units, of which 216 units are situated above the Ilam Dam. The minimum and maximum amounts of sedimentations in this units 2.3 and 26.7 ton/h/year and the average of produced sediment of the region is estimated by MPSIAC model as 14.98 ton/h/year. The amount of sedimentations in the basin has been estimated at 32994.9 tons per year and The amount of sedimentations of the basin at the dam has been calculated to be 2340309.13 tons per year which is tantamount to 181716.12 cubic Meters per year. Furthermore the amount of sedimentations of the basin at the Amir- Abad diversion dam, without calculating its six above sub- basins, has been estimated to be 265016.77 cubic meters per year. Considering erosion classes and sedimentation intensity, the basin has been divided into classed called low, medium and high classes.

Temperature is the most important environmental factor that affects flowering and fruiting. The temperatures induce reproduction and cause damaging to tree or its crop. This paper analyzed daily minimum temperatures 0.0 oC, and maximum temperatures 12.5 oC from October 1 to May 31 at nine sites in olive producing and cultivating regions, and one control station, using thermal adaptability model. To determine the probability of high temperature damage during flowering within each region, temperatures equal to or higher than 37.8 oC were considered. To determine damage produced by last frost, temperature equal to or below 0 oC that occurred during flowering within each region, was considered. The model has introduced indicates that Shiraz, Manjil, Gorgan, Gonbad and Sarpol zohab stations show Temperature pattern similar to olive producing regions.

This survey accomplished for asessment and mechanism recognition of Chenaran watershed landslide effective factors and its zonation based via LIM model. Primarily recognized effective factors, through studing and field survey and evaluated by Landslide Index Method (LIM) then based on their weight in model, landslide hazard zonation was done. then evaluated this model competence in zonation, by cross operation between landslides and zonation maps.the results show that, Shurijeh formation (Ksh) consists of clay, marly & evaporites impermiable layers, soluble calcareous sement and maximal weight (Lnwi=2.3341) is very important factor for landslide generating in Chenaran watershed. then aquifers, garden landuse, altitude (1570-1715 meters) and its processes, slope (38-78.8 degrees), Chenaran river undercutting and snow cover agent in shape of effective factors at mitigation shearing resistance and augmentation shearing stress have maximal impact at basin's landslide. About 89.35 percent of basin,s landslides are located in areas with richly potential that shows this model ability at landslide zonation.

Paleo-Geography investigation of coastal area is one of main topic of coastal researches. Recognition of coastal zone Paleo-geography will indicate coastal evolution and geology and hydrodynamic processes which dominate in that area. Coastal Makran zone which is known as active coastal area is located between 250, 15´ to 250, 30´N and 590, 15´to 610, 21’ E in south- east of Iran. This area is composed of Omega shaped bays, sandy beaches, estuaries and marine terraces. The main goal of this research is recognition and planning of late quaternary Paleo-geography of Coastal Makran zone. Research methods are based on GIS and 14C dating and filed observations. The main achievement of research is planning and identification of late quaternary Paleo-geography indicators such as Paleoshorelines and sea stocks in Guader, Chabahar, Pozm and Gurdim bays and Tang, Drango, Karti and Galak estuaries. The age of Paleo-geography indicators (Paleoshorelines) was obtained by 14C dating of some fossil samples. The oldest Paleoshorelines is 17600 years old that locates at north of Chabahar bay caused by Flandrain sea transgression after last maximum glaciations at 18000 yr BP. Also, 22 Paleoshorelines developed at north of Chabahar bay are constituents of regression coasts created during sea level falling or uplifting of coasts at late quaternary. Results showed that the construction duration of each paleoshorelines at Guader, Chabahar and Drango bays lasted 113, 223 and 130 years respectively. Due to neo-tectonic events, uplifting rates have increased as much as four times since 5000 yr BP. On the other hand, Mio-Pliocene rock units as islands and detached breakwaters cause sedimentation behind them and creation of Tombolos and then Omega shaped bays.

In order to study the type and range of the changes in TAJAN basin, in recent year, the images of TM and ETM+ were studied. For assessment of land use changes after enhancement and geometric correction, differencing change detection techniques, false color composite, vegetation index and post- classification comparison methods were used. The result of this study indicates the extended land use changes including decrease of forest extent, rangeland and increase of agricultural land and gardens. Analysis of runoff and rainfall from 1969-1970 to 2000-2001 periods indicates that in spite of decrease of rainfall amounts, the runoff has increased ,while the total mean of vegetation index and the mean of vegetation index of forest and rangeland has decreased about 12.89, 9.85, 34.7 percent respectively. With consideration of stability of topography, slope gradient results show runoff increased in this area due to decrease of vegetation. Therefore climatic and environmental factors had not important role on increase of runoff in studied basin.

A mountain glacier, when it occupies a river valley, immediately begins to change the cross-section and profile of that valley. River valleys in mountain areas tend to have V-shaped profiles. Glaciers work to widen as well as deepen their valleys and the typical cross-section of a glacial valley is U-shaped. The U-shaped glacial valley is one of the most characteristic of glacial landforms. With growth and spreading of ice cap in Sahand Mountain in late quaternary (wurm), many of Sahand valleys (northern and northern west valleys) have about characteristic of glacial valley. But in comparison with Alpine landscapes, it has rather had development. In fact study of cross-profiles of Sahand glacial valleys and simulation model of form development, shows that these valleys are in third time step. The importance of cross-section of glacial valleys has made it the focus of this study. Therefore models of glacial valley development were used in Sahand glacial valleys. Graf relations, ratio of valley depth to its width, have coincidence only in a few cases. Mathematical equation, Y=aXb (where Y is the vertical, and X the horizontal distances from the midpoint of the valley bottom, a,b are constants) and other equations is used in one relatively typical glacial valley namely Ligvan Chay. Results show there is poor relation. Therefore glacial valley of Sahand mountains have had little evolution.

This research was conducted in the Pegah - Sorkh sub-catchments area, a semi-arid region in SW Iran, Using Geographic Information systems (GIS) and Remote Sensing (RS) to compare the Erosion Potential Method (EPM) and Modified Pacific Southwest Interagency Committee (MPSIAC) models in erosion-potential mapping and sediment yield assessment. The study area with approximately 4600 Ha shows different type of lithological units and vegetation covers. Data were collected from available sources were further processed with image processing and field observations. Also all the factors needed for EPM and MPSIAC models were provided using common abilities of RS and GIS. Comparison of the EPM and MPSIAC results with field observation showed that although the results of the two erosion potential maps are very similar, but the results the MPSIAC are reliable in identifying areas with very high erosion potential.

The purpose of this paper is to inform students and researchers of geomorphology from the situation of this science at present and in future, in Iran, after the Islamic Revolution. To fulfill this purpose and to prouide full information about the situation of geomorphology in Iran, various areas of this science are presented chronologically at the beginning of the article. The findings of this study shows that, daring the last twenty five years, geomorphological studies were concentrated in the four areas of general geomorphology, fluvial, structuran and mass moments morphology. Other subjects like weathering, wind proce, Coastal, Glacial and applied geomorphology were not considered so much. Although the findings of this article proves that geomorphological studies are started again, after the Islamic Revolution but, still there is a long way to go for achieving the desired situation.

The aim of this paper is to investigate annual and seasonal precipitation trends of some selective meteorological stations of central region in Iran using non-parametric methods. Two non-parametric methods including Mann-Kendall and Sen's estimator slope methods were used here to analyze the seasonal and annual trends of precipitation data. Some 48 meteorological stations in central region of Iran which in the period of (1971-2000) had full records were selected and two mentioned tests were applied and results were compared. The results showed that the application of these two methods is almost similar, although the Sen's estimator slope method showed better performance where the number of zero in the time series of data was considerable. There is a significant negative trend in both tests in some of the time series, but no significant positive trend for both tests was confirmed. Since the number of series with significant trend in comparison to series without any trend was small, therefore a general trend can not be attributed to the region.

Soil erosion is one of the main problems in terms of natural resources. Some methods can be to control erosion with studying its factors. In first, to determine the effects of topography on the soil erosion intensity, some homogeneous zones were selected in terms of geology and land use in the west of Zaremrod watershed. Topographic units were extracted in these areas .The mean topographic factors (slope, aspect, elevation) were estimated using Arc/View (GIS) software in 30 topographic units. Also the mean erosion intensity was estimated. Finally, these values were analyzed with Multi-variant Regression method using SPSS software. In this stage, erosion intensity was selected qua dependent variable and topographic factors independent variables. The results of this study showed that slope has the most correlation with soil erosion intensity. Also, slope aspect has significant relation with erosion intensity and elevation has not significant relation with erosion intensity.