extraction of soil salinity zone in arid and semi arid regional using of remote sensing data (case study: darab township)

introduction soil salinity and expansion tts it, in the arid and semi-arid areas is including environmental issues that in recent years attention has been due to population growth and the need to utilizeland. in order to human was tried that using of different techniques determined salinity area between remote sensing data in recent years have provided relatively accurate results as a source of information (long & nielsen; 1987, 221 : everitt et al; 1988, 1283 : csillage et al; 1993, 231 : verma et al; 1994, 1901 : bishop &mcbratney; 2001, 149 , carre& girard; 2002, 241 ,douaoui; 2006, 217, fernandez-buces et al; 2006, 644: melendez-pastor et al; 2010, 55: gutierrez & johnson; 2010, 46,bouaziz et al; 2011, 237). also in iran has been studied with remote sensing data and technique (abdinam; 2004, 33, dashtkian et al; 2008, 139, nourozi et al; 2011, 59, zare; 2011, 74).remote sensing is as technique and science access to information about the phenomena without physical contact with the area. also geographic information system is used as a system in collect, store and analyzes information related to the phenomenon. obviously, that both techniques are appropriate for gathering information, making fast, accurate. in the two late decades using of field technique and mixture to remote sensing data has been significant aid to mapping of soil salinity. remote sensing has capability and potential to extraction and problem study of salinity in large-scale zones. also remote sensing has provided forecast possible, assessment of salinity effect. extractive salinity map has capability much in agriculture and other human activities. darab township is including regional that have environmental conditions ofaridan dsemiarid, one of problems has been soil salinity.in this research we tried to using of landsat satellite image and also field survey extractive salinity zones and analyses due to salinity. study area darab township located in southeast fars province and 54o, 11// to 54o, 24// east longitude and 28o, 33// to 28o, 49// northern latitude. viewpoint of geomorphology study area is part of zagros south east (fars region). in this region zagros reached its maximum width and face rough appearance is different from other parts of the zagros. so that waves of chains is more open and is panache as syncline ponds and anticline disks. syncline ponds often has created very open plain (darab plain) through arrival of anticline axis connected together.most of the rainfall occurred in january. in the summer it has been very hot and dry climates due to being away from moisture resource, water vapor entry path and sometimes the lack of qualified. this dryness status is also reflected in the rain. of course is seen in darab summer monsoon rainfall that is related to the southeast regime. this property is reflected in the days of 10 mm. material and method in this paper the materials relate to the topic was collected first using. after according to purpose research was used from satellite images landsat (landsat tm path and rows 161 and 40 to june 15, 2010 and 16 june 1987, with a pixel size for the thermal band 57 meter band panchromatic 25/14 meters and for the rest of the band 79 m). this image was downloaded of the glcf site for easy access.after using of landsat image satellite (1987 and 2010 years) and khaier method (2003) through detectiontechniques (band 5 – band 7 / band 5 + band 7) in software has extracted soil salinity zones. for superimpose of extraction map salinity zones to fact was doing field survey of study area. we should say that the main technique in this research is detection pixels salinity represented. also in this study using of geology and topography maps, digital elevation model (dem) 30 m of aster. to calculate the impact of climate factors was analyzed darab synoptic station data. for ensure and accuracy finding was performed three stages of field survey. in the first stage was observed landforms of near. in the second phase was photographed of saline lands, their distance from salt domes and water way transport salt. in the third stage to validation findings was a complying extraction zone (with varying degrees of salinity) withthe earth surface, to have determined rate accuracy of calculation and soil salinity map. finally was concluded based on research finding and investigate their right. results and discussion based on output map (image 2010), 545.37 square kilometers of the study area has high salinity (8.33 percent), 1804.69 kilometers with significant salinity (27.58 percent), 2343.41 square kilometers represent moderate salinities (35.81%), 1645.23 square kilometers represent low salinity (25.14%) and 204.91square kilometers from the city darab has very low salinity (3.13 percent). compare this map to extraction map (1987) has showed reduction highsalinity, significant,insignificant zones and increased lowand mediumsalinityzones. result showed that salt domes are main factor salinitization of soil and between corsia salt dome played most of role. in around of corsia salt dome existences salinity springs that not observed in other salt domes. every year the significant amount of salt through these springs has left besides the corsia salt dome. field observations show that almost half of the salt dome has been eliminated in the erosion caused by flowing water (rainfall showery). their main symptoms are formation of salt fan in the foot of the salt dome.in late years human with creation trench cause to aggregation armed with salt water. it is interesting to note that field visits showed that salinization of lands caused by corsia salt dome erosion has cut in the time to around, in other words has been limited salinization.it can be because limit is appearance of shahyjan river in east salt dome and golabi spring in west its. seem that extraction map of salinity zones can be significant role in environmental management for achieve tosustainable development.major of land high salinity located in west and southeast of darab.can be that diversity of landforms has led substantial area (60 percent) of the land in darab are capable to cultivate. of course in north and northeast are seen salt stains that due evaporate sediments. exist of diver alluvial fans in north darab and fresh floods that every year transport and left significant amounts of sediment (including soil, etc.), its watershed from upstream to downstream and the city. so many of alluvial fans of darab is active and been developed (but human interpretations of the sediments should be noted) and prone lands have been prepared for cultivation. conclusion the main operating of salinity is salt dome in the study area. in darab town existence six salt domes that among them corsia salt dome plays most role in salinity of lands. around this salt dome existences spring that each year remained a significant amount of salt in surrounding. due to high salinity in around salt domes only plants can be growth that was resistant to salinity. in addition the effect of salt domes in the soil salinity, also groundwaters are affected by then. so that in khosoei strait the electrical conductivity of waters appears up to 5000  m per square centimeter. existences of river and fresh flood have caused prevention to expansion of saline lands and its have washed the area well land and salt transport to khosoei strait.in the mouth of the khosoei strait man has attempted to create a barrier that behind the dam each year, some salt is left behind. in the past that that there was no barrier waters moved to the southeast through the narrow river tngecharkhi. salinity of forg and abshore area in southeast darab was as a result, the river crossing. of course join water of fedami waterfall to river reduces extent of salinity in this section.so that palm groves and lands in section irrigation to river water.the achievement of this research is to determine to the salinity zones, identify and analyses effective factors on soil salinity in study area. output map as a scientific document can play a significant role in environmental management.