نشریه جغرافیای طبیعی
پیاپی 8 (تابستان 1389)

Annually, climate hazard in Iran leave financial and man loss. According to this, acquaintance and asses this hazards include high importance in order to reduce its effects. Regarding to the vast geographical extension of Iran and unsuitable dispense of land sensing stations, access and gathering land hazards data had encountered many problems and difficulties. Today, developing technology of remote sensing, there have been made great opportunities in gathering and assess hazards. In this research, dust storms hazard in July 1, 2nd 2008 in Khuzestan, flood in Feb 11, 2005 in Chabahar and Gono in 6 Jon 2007 have chosen for consideration and study. Assess this hazard have been made by AVHRR, MODIS, SEAWIFS, VISSR sensors and also TM and MSS, in some cases.
In the current research, visual observation method has been used for hazard recognition in images. In this method, for hazard recognition, we use features such as: tone, color,shape, size and tissue that each one are as an appear characteristics. Besides, color composite images (RGB) has been used for detect hazards with special color, in this research. Ultimately geometrical correction did on images for assess the cover surface. The study results show that for hazard tracing, high temporal resolution sensors and for inform of details and source of spatial resolution hazards, are practical and useful. For detection dust storms, the SEAWIFS, MODIS and also MODIS sensor has been introduced more useful than other sensor also for flood detection. METEOSAT satellite sensor has been introduced as the best sensor for assess the heavy rainfall because of super temporal resolution (each 15 – 30 min).

In order to analyze the synoptic origin of precipitation of the Larestan area, the rain days with more than one millimeter rain were obtained from the Iranian Meteorological Organization for the 1960-2007 periods. First the wet periods of 1-6 days long were determined. From these wet periods the most intensive and longest rain period during both cold and warm seasons were identified as February 1993 and July 1995. The synoptic systems producing these rain periods were extracted from the 12 GMT surface and 700 hPa and 500 hPa maps. The results of the study showed that the main pressure patterns of these rains are westerly cyclones, Sudan low, and upper level troughs during cold season. But during summer season the Monsoon and weakening Subtropical High are main pressure patterns.

One of the obstacles in the development of Gol-e-Gohar iron ore in Sirjan is the shortage of fresh water in the region. Chah_Deraz plain aquifer that located in adjacent of salty pan of Sirjan, is currently one of the sources of required water supply of Gol-e-Gohar mine, but salt water take in the lower aquifer, has limited the increasing withdrawals of fresh water. Optimal management and developing withdrawals of the aquifer requires knowledge of the placement position of the mass of salt water in the aquifer. This study tries to determine the status and border of salt and fresh water by reviewing hydrochemistry of aquifer and sampling of observation wells as deep and surface and measuring electrical conductivity. Groundwater level around exploitation wells is about 1685 meter and in output areas output of the plain is about 1690 meter. The situation of the border of the salt and fresh water exploitation wells in downstream is 1625 meter and around the exploitation wells at 1649 meter level was determined. Also groundwater model results show that by increasing the pumping wells twice, a drawdown of three meter is occurred around exploitation wells which in turn the salt water with electrical conductivity of more than 10000 μs/cm intrudes to the floor of exploitation wells.

One useful way in providing water in dry areas is to increase the amount of underground water resources. Construction of underground dams and optimum use of surface water are two ways for providing and developing water resource. The first and most important step in the construction of an underground dam is to identify suitable site for dam construction. In this study, after considering the results of onducted researches and examining basic information by using RS and GIS techniques the suitable site will be selected. It is remarkable to note that there are many factors which play important roles in selecting the suitable site; therefore the use of Analytical Hierarchy Process (AHP) will be very helpful to make a right decision. It should be noted that 27 suitable sites were identified in the initial stage. However, only 9 regional priorities that were introduced in the form of a map are given the priority ordering.

Geomorphic systems in systematic geomorphology approach are non-linear complex dynamic systems which have chaotic, random and unpredictable behavior. The theory of chaos studies these non-linear systems which are sensitive to their primal conditions. Geomorphic systems are however self-organized and Fractal indeed. This property could be seen in many fluvial, mass movements, soil systems and coastal wetlands. The chaos theory helps us to make a relationship between Form (Fractal dimension) and process (selforganized) in geomorphic phenomena. Chaos theory helps to recognize, analyze and perceive predictability of geomorphic systems. Complexity and chaotic behavior of geomorphic systems are so extraordinary that we cannot definitely apply math and physic rules on them or generalize them into a large scale. So, new approaches try taking use of simple and micro scale rules (math and physic) in the form of cellular automata models for analyzing & simulating the non-linear complex systems behavior in geomorphology.

Improper use of land has led to gradual erosion and degradation, reduction of crop products as well as decreased benefits of agricultural areas and rangelands. Therefore, planning for proper use of the land based on its capability and land use optimization is an important and major solution in soil conservation practices. The main purpose of this research was to determine optimum area of each land use in order to decrease soil erosion while to increase income in Zakherd catchments. The study area is located in Fars province, Iran. First, land use map of the region was prepared based on Land sat satellite images and field studies. Then, the rate of soil erosion was predicted by implementing MPSIAC model. Meanwhile, the net income for each land use was calculated separately. After characterization of limits and objective functions in the study area, optimization area for each land use was obtained by using multi-objective linear programming. The obtained results revealed decrease of dry and irrigated farming and increase of orchards and rang lands in the optimum condition. It means that orchards and rang lands area increased up to 212.87% and 303.26%, respectively while dry and irrigated farming area decreased to 65.02% and 57.55%, respectively. Also, the results indicated that land use optimization could reduce soil erosion rate in the study area up to 13.16% whereas the benefits were increased at rate of 27.04%. The results of sensitivity analysis of the model parameters showed that any change in the area of orchards and dry lands farming will have the most impact on the benefits and soil erosion change of the studied catchments.

Semirom is located in Zagros Mountains in the south of Isfahan. It has changing climate conditions including semi-arid in the north of the city, Mediterranean climate in the center and semi-humid to humid in the southern part. Generally, this city has a hot and dry climate in summer and cold and humid in winter.
This area has been known for its nice weather in summer and considering its natural attractions, it has a high potential in attracting visitors. But this potential has not been well exploited. To promote tourism in this area, we need to specify proper times and places for visitors. Among the visitors’ basic needs knows about the climate and proper times for traveling.
In this study, proper times and places for visitors have been specified through using Tourism Climate Index (TCI) and GIS potential in interpolation, generalizing point data to scatter data and combining maps. The findings of this study indicate that the best time of year to attract visitors to this area is September followed by May. January, February, March and December are the worst months. Also, the northern part of the city has better conditions to attract visitors than the southern part as far as local distribution is concerned.

The alternative occurrence of high water and water scarcity in the basins is evident phenomenon. The occurrence of these periods in the Kasha's basin, addition to effect on quantitative condition of surface water, cause to changes in the quality of water in this basin. So, in this research using regression analysis in the soft ware’s environment Spss, Excel follow two main purpose. First, the study of relationship between high water and water scarcity periods with quality parameters of Kashkan basin’s surface water. Second, evaluating the surface water’s quality of mentioned basin for use in the agricultural and watering use during the high water and water scarcity periods. So, use the analyzed statistic of 12 parameters of water quality and daily discharge statistic of 8 hydrometer station in the rivers such as Dehno, Doab Aleshtar, Upper Kashkan, Khorram Abad, Middle Kashkan Cholhool, Madinrood, Down Kashkan in the 30 years (1351-1380) statistic periods.
Also flow continuity curve draw for each of mentioned rivers and extract the Q95 index as hydrologic drought threshold from this curve. The result show that in the majority cases, there is meaningful logarithmic relationship between high water and water scarcity periods with water quality’s parameters, and in the following of high water and water scarcity periods, the amount parameters of studied water quality in this rivers have upward and downward trend and lead to changes in surface water’s quality of this basin. Also, with evaluating the surface water’s quality of basin for agricultural and watering use indicate that in the alternative wet and dry period, the water of rivers such as Dehno, Doab Aleshtar, Upper Kashkan, Khorramabad, Middle Kashkan and down Kashkan has been among the good quality water and in the Cholhool and Madianrood rivers was acceptable and medium.