فصلنامه پژوهش های جغرافیای طبیعی
پیاپی 68 (تابستان 1388)

In semi arid area geomorphological impacts of dams are very major. Dams, as man- made structures, have major impacts on river hydrology, primarly through in the timing, magnitude, and frequency of low and high flows, ultimately producing a hydrologic regime differing significantly from the pre-impoundment natural flow regime. Despite the profiles of dams on river regulation for water resources management, they create artificial flow regimes downstream and also interrupt the transfer of sediments from headwater source area. These changes are started on acts of the fluvial processes at below dams, and caused adjustments of channel form. For study of effects of dams on upstream and downstream of semi arid catchments, Garangoo,s catchments is selected.This catchment is located on eastern slopes of Sahand Mt., (from 46°. 27' to 47°. 42 E., from 36°. 58´ to 37°. 44´N). In this paper emphasizes the downstream effects of Shand,s dam on Garangoo river, on the sedimentatation,s rate of dam and also, on the effects of dam of Sahand on downstream geomorphology. For assessing of rate of erosion, amount of sediment, is used of bivariated method and GIS and then produced map of suitable area for erosion, sedimentation and landslides. The mapping is often performed through the identification and analysis instability factors. For mapping, firstly distribution map of factor produce and digitized of factors and then analyzed by bivariated methods and the next stage, weighted to factors and final stage, produced hazard donation map by using of Arc/View. This map shows that, upper part of Garangoo,s catchment, erosion is critical and about of all products of erosion processes and materials of resulted by the landslides occurrence, remove into streams, and the final stage, deposit in sea of dam. The results of study also show that, responses of rivers to damming are as linear erosion, lateral erosion, meander and deeping river's beds.

Through this article, the distribution of air pollutants in Tehran have been simulated based on wind patterns with and without the presence of synoptic by TAPM (a meso-scale model). The simulation covers three horizontal resolution domains 30, 15 and 5 kilometers. The pollutants chosen for this are CO and PM10 and wind data is 10 meter height level. The result has shown that the model simulated the wind direction with an index of agreement 90 percent, the wind speed with 60 percent and the emission about 51 percent. This can be acceptable, because the station measures the pollution based on point sources while the model does simulation in the surface level.The statistical result also has shown that concentration of pollutants increases from north to south and east to west. The variance analysis shows that two city zones (11, 12) are the most polluted areas and the zone 21 is the cleanest one. This is due to the wind direction ruling in Tehran. With the presence of synoptic conditions, the wind speed increases in height level and the contours show harmony while in conditions without the presence of synoptic, the wind speed decreases and the contours do not show any harmony. Since the wind speed is almost always less than the Tu. Coefficient, it is not expected that the wind refine the air in Tehran.

Estimation of pure runoff is a house virtually is complex and different methods of calculation have been proposed. Modern methods of solving problems in river engineering and water homes and assess the flow method is used, is that the artificial network pattern of human brain neural network training process, while implementation of the internal relationships between the data and discover for other situations will generalize. The main objective of this study to estimate the runoff through the analysis of relations rainfall-runoff by geomorphology and quantitative data and using geomorphologic artificial neural networks technique in Amameh sub basin in Jajrood basin. This study based on geomorphologic stracture and ed Hydrologic network, a geomorphologic system with three-layer neural network with the number of intermediate nodes or the number of paths situations hydrology network in order to estimate direct runoff was established. The weights of system input connections within the network structure model determined with using geomorphologic variables. Results from the above network model with information derived from direct observations to indicate the efficiency was compared. Assessment results, indicate a very good function (R2=0.97) geomorphologic network model to determine the response of hydrological basin is studied. Means, this model shows the preference of them than the other common procedure methods.

Policy making and planning for agricultural development and conditional improvement of rural and farmers requires accurate and real time information and statistics. In Iran, accessing relevant agriculture statistics is mainly gained through expert knowledge and traditional methods. Studies show that these have a high percent of error. This research has been aimed so to, by using new methods including RADARSAT data and Remote Sensing techniques, meet agricultural statistics and information with minimum error. using data integration in Geographic Information System, not only leads to the results with high accuracy, but also it will be possible to input, save, retrieve, and analyze complex data for modeling different resources activities. In this research, RADARSAT data acquired in 1998 and TM LANDSAT images used to map and estimate paddy Rice agricultural lands in SARI suburb. After geo-referencing of data, different image processing techniques such as data classification based of MLC have been used. Results show that statistics generated from remote sensing techniques are much more accurate than those reported from traditional methods.

Nowadays researchers are paying due attention to climatic parameters in order to offer justifiable grouping for farm products cultivation areas. Accordingly, the influence of climatic factors has already been proven in regard with the regionalization of vineyards. Although the temperature parameter has been emphasized so far, it seems that relying on single-parameter techniques has not been such effective in regionalization. Based on such an assumption from quantities of monthly minimum temperature, maximum temperature, precipitation, relative humidity, mean wind speed, and besides amount Penman potential evapotranspiriation in 45 synoptic stations of Iran in January-September from 1985-2005 that according SCI. Organization site were grape-growing regions, 3 index "Huglin's heliothermal, cool night, potential water balance index of Riou" have been calculated. These indices are representative of variability of viticultural climate of Iran. Then 16 climatic groups of grape-cultivation areas were identified using Tonietto and Carbonneau (2004) technique and their specifications were studied. Central and eastern regions of Iran were included in the hot region with hot nights and high aridity; while other regions enjoyed climatic variations. Based on the patterns introduced in this paper, it is possible identify new areas with higher potential for grouping grapes and achieving the highest yield in production, using different varieties of the cultivated grapes in different climatic areas.

This research that was made on 66 cyclones in wet periods of Midwest of Iran in a given period (1973-2003) shows that in intense wet periods, cyclogensis centers of Mediterranean sea, Sudan, Red sea and Mesopotamia were severely active and have been very effective in rainfall of study area. Such systems in general, with respect to dominant synoptic patterns, enters into study area from three main tracks: A) From west and central Mediterranean cyclogensis centers and also north of Cyprus island toward northeast of study area. These systems with reinforcing in east of Caspian Sea follow to Aral's lake. B) From cyclogenesis area of Cyprus and north of Mesopotamia toward study area in east of Zagros ranges extended to northeast and Aral's lake. C) From Cyprus and north part of Red sea and Mesopotamia toward north Persian Gulf and by passing from Zagros ranges extended to southeast and northeast of Iran. Cyclone's frequency and tracks have change very much in autumn because of variation in equatorward motion of STHP. Winter cyclones have long duration than the other seasons and their central pressures are higher than spring and lower than autumn ones. In addition, these cyclones- because of their dynamic conditions- have longer tracks. Although spring's cyclonic tracks have more variety, but with slight change two marked tracks of winter are also shown in spring.

Manoeuvre, is One of the principles of war in most of the world’s armies. Mobility and manoeuvre of the operational and support forces in the battle fields occur in bed of natural and cultural geographic factors, i.e, avenue approach and frontier transportation networks. So for this reason analyzing this geographical Factors in skills such as line identification in tactical and operational levels will perform by communicational and operational commanders and officers. East-Azarbyjan is one of the 16 frontier province of Iran, which is always considered as a chief of all frontier provinces. Its extension from East to West and the parallel form of its mountains areas limit civic relations with outpost areas just from especial axises. Axisis without proper road-connections is deficient in military activitites. So, a deep survey on the importance of transportation system in this province is quite necessary for militarist. In this research for military analysis digital information pads were created with the use of Arc gis 9.2 software to format pad for east Azarbayjan, the leading frontier accesses were recognized and various tactical dimensions like control points, defence positions, beacon zones, concealment, camouflage, daily tonnage capacity and geographical positions were analyzed. After ward, numerous maps from beacon zones, straight and non straight scopes, linear profiles, proper and substitutional strands for frontier roads were prepared and the posed questions were responded and the research hypothesis was tested.

The main aim of the current paper is to discuss the important effective variables, particularly synoptic patterns, in creating flood in Masoule basin using flood discharge data in Komadoul station during 20 year period (1984-2003). To achieve the aim, daily average and instantaneous maximum of discharge in mentioned station were used. Data accuracy was done using the data for Chomesghal station and technical report from the unexpected events section in the area. In the study period, among the 181 identified flash flood events, 61 events were chosen between years 1996-2003. Then, based on the most effective creator parameters, they were classified into two main groups; events which were due to atmospheric instability and synoptic patterns and those occurred as a result of combination rainfall and short length of main channel. About 51% and 49% of destructive floods in the study area belong to the first and second groups, respectively. Using the synoptic maps of surface level, 700 and 500 HP, and based on the position of cyclone and anticyclone on basin and their movement over the moisture resources, three specified patterns was distinguished. The cyclonic systems come from Mediterranean Sea and Black Sea, while the anti-cyclonic models mainly come from Caspian Sea and rarely from Black Sea. The result of the research also showed that mentioned systems, based on their characteristics or establishment period on the basin, have been made flood with different magnitude. Among the sampled events, 34, 13, and 14 events were adjusted with one, two and three consecutive day rainfall, respectively. From the temporal point of view, distribution of flood shown that most of them were occurred between Sept. and Oct., late winter and early spring.