نوع مقاله : مقاله پژوهشی
نویسندگان
1 پردیس کشاورزی و منابع طبیعی دانشگاه تهران
2 کارشناس ارشد آبیاری و زهکشی پردیس کشاورزی و منابع طبیعی دانشگاه تهران
3 استادیار گروه مهندسی آب دانشگاه گیلان
4 دانش‌آموخته دکتری گروه خاکشناسی، دانشکده کشاورزی، دانشگاه تربیت مدرس
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Salinity is a phenomenon that does not satisfy the crop water requirement and leads reduction vegetation. To control of this phenomenon requires appropriate management and monitoring of spatial and temporal salinity variations from the past to the present
In this study the spatial and temporal changes of soil salinity of irrigation and drainage network located in Garmsar, Iran, is investigated from 1986 to 2013. For this purpose, using satellite images and ground data, temporal changes of field area ratio are studied in three salinity levels of low, medium and high at the end of fall and spring planting period during these years by and five satellite indexes. Finally trend of changes is determined using Mann-Kendal test.
Also determined the trend of changes the value of each salinity index’s pixel by Mann-Kendall test and zoning changes the salinity was extracted Results show that with a probability of 95%, at the end of fall planting period the trends of area ratio of fields with low, medium and high soil salinity are decreasing, increasing and increasing, respectively. At the end of spring planting period, trends are similar to fall planting period for fields with low and high levels and medium level shows no significant trend. Also zone classification of soil salinity show that north, south and west regions of Garmsar plain are at the risk of increasing salinity during the time and the north-east and central regions that have secondary irrigation network presents a decreasing trend in soil salinity. During considered years, of the total 16 thousand ha areas, fields with low soil salinity decrease around 6.5 thousand ha and the areas of fields with medium and high salinity increase around 4.5 thousand ha and 2 thousand ha, respectively, in this region.
کلیدواژه‌ها [English]
Salinity lowers plant water uptake and therefore crop cover. Control this phenomenon requires appropriate management and constant monitoring of the spatial as well as temporal salinity variations from time to time. In this study the spatial and temporal changes in salinity of Irrigation and Drainage Network soils in Garmsar, Iran, were investigated from 1986 to 2013. To Follow the purpose, employing satellite images and on the ground data, temporal changes of field area ratio were studied in three salinity levels of low, medium and high at the end of fall and spring planting seasons during the mentioned years through five satellite indexes. Finally the trend of changes was determined applying Mann-Kendal Test. Also Through a determination the trend of changes, the value of each salinity index’s pixel (through Mann-Kendall Test) as well as zoning changes the salinities were extracted. Results indicate that (with a probability of 95%), at the end of fall planting period the trends of ratio of fields with low, medium and high soil salinity are decreasing, increasing and increasing, respectively. At the end of spring planting season, trends are similar to fall planting period for fields with low and high salinity levels and while medium levels indicating no significant trend. Also zone classification of soil salinity shows that north, south and west regions of Garmsar plain are at the risk of increasing salinity during the time while the north-east and central regions that are equipped with secondary irrigation network present a decreasing trend in soil salinity. During the considered years, of the total 16 thousand ha area, fields with low soil salinity decrease around 6.5 thousand ha while the area of fields with medium and high salinity increase for around 4.vs. 2 thousand ha, respectively, within the studied region.
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