پديد آورندگان :
ﯾﻐﻤﺎﺋﯿﺎنﻣﻬﺎﺑﺎدي، تفيسه داﻧﺸﮕﺎه ﮔﯿﻼن - گروه ﻋﻠﻮم ﺧﺎك , اسدي، حسين داﻧﺸﮕﺎه ﺗﻬﺮان - ﮔﺮوه ﻋﻠﻮم و ﻣﻬﻨﺪﺳﯽ ﺧﺎك , رضايي، صديقه داﻧﺸﮕﺎه ﮔﯿﻼن - گروه ﻋﻠﻮم ﺧﺎك
كليدواژه :
ﺑﯿﺎﺑﺎن زاﯾﯽ , ﻣﺪاﻟﻮس , ﺳﺎﻣﺎﻧﻪ اﻃﻼﻋﺎت ﺟﻐﺮاﻓﯿﺎﯾﯽ , ﮐﯿﻔﯿﺖ ﺧﺎك
چكيده فارسي :
ﺳﺎﺑﻘﻪ و ﻫﺪف: اﻣﺮوزه ﺗﺨﺮﯾﺐ اراﺿﯽ در ﻧﺘﯿﺠﻪ ﻋﻮاﻣﻞ ﻣﺨﺘﻠﻔﯽ ﻣﺎﻧﻨﺪ ﺗﻐﯿﯿﺮات اﻗﻠﯿﻤﯽ و ﺑﻬﺮهﺑﺮداري و ﻣﺪﯾﺮﯾﺖ ﻧﺎدرﺳﺖ اﻧﺴﺎن، ﺑﻪ ﻋﻨﻮان ﻣﻌﻀﻞ ﺟﺪي در ﺑﺴﯿﺎري از ﻣﻨﺎﻃﻖ ﺧﺸﮏ، ﻧﯿﻤﻪ ﺧﺸﮏ و ﺧﺸﮏ ﻧﯿﻤﻪ ﻣﺮﻃﻮب دﻧﯿﺎ ﻣﻄﺮح ﻣﯽ ﺑﺎﺷﺪ. اﯾﻦ ﭘﺪﯾﺪه ﻣﺪت ﻫﺎ اﺳﺖ ﮐﻪ ﺑﻪ ﻋﻨﻮان ﯾﮏ ﻣﺸﮑﻞ ﺟﺪي اﻗﺘﺼﺎدي، اﺟﺘﻤﺎﻋﯽ و زﯾﺴﺖ ﻣﺤﯿﻄﯽ در ﺑﺴﯿﺎري از ﮐﺸﻮرﻫﺎ ﺷﻨﺎﺧﺘﻪ ﺷﺪه اﺳﺖ .ﺑﺮاي ارزﯾﺎﺑﯽ وﺿﻌﯿﺖ ﺑﯿﺎﺑﺎن زاﯾﯽ و ﺗﻬﯿﻪ ﻧﻘﺸﻪ ﻣﺮﺑﻮط ﺑﻪ آن ﻣﺪل ﻫﺎي ﻣﺨﺘﻠﻔﯽ اراﯾﻪ ﺷﺪه اﺳﺖ .ﻣﻨﺎﺳﺐ ﺗﺮﯾﻦ روش ﺑﺮاي ﺑﺮرﺳﯽ ﻋﻮاﻣﻞ ﻣﺆﺛﺮ در ﺗﺨﺮﯾﺐ اراﺿﯽ و ﺷﺪت ﺑﯿﺎﺑﺎن زاﯾﯽ از ﻧﻈﺮ ﻣﺘﺨﺼﺼﺎن اﺳﺘﻔﺎده از ﻣﺪل هاي ارزيابي بيابان مي باشد. مدل ESAs به علت آساني ،در دﺳﺘﺮس ﺑﻮدن داده ﻫﺎ و ﺳﺎزﮔﺎري ﺑﺎ ﺷﺎﺧﺺ ﻫﺎي ﻣﺆﺛﺮﺗﺮ در ﺗﺨﺮﯾﺐ اراﺿﯽ و ﺑﻪ ﮐﺎر ﮔﺮﻓﺘﻦ ﻣﯿﺎﻧﮕﯿﻦ ﻫﻨﺪﺳﯽ ﺑﻪﺟﺎي ﻣﯿﺎﻧﮕﯿﻦ ﺣﺴﺎﺑﯽ، ﻣﺰاﯾﺎي ﺑﯿﺶﺗﺮي ﻧﺴﺒﺖ ﺑﻪ ﺳﺎﯾﺮ ﻣﺪل ﻫﺎ دارد. ﻫﺪف اﯾﻦ ﭘﮋوﻫﺶ ﭘﻬﻨﻪ ﺑﻨﺪي و ارزﯾﺎﺑﯽ ﺗﺨﺮﯾﺐ اراﺿﯽ در ﺣﻮﺿﻪ ﺳﯿﺎﻫﭙﻮش اﺳﺘﺎن اردﺑﯿﻞ ﺑﺎ اﺳﺘﻔﺎده از مدل ﻣﺪاﻟﻮس اﺳﺘﺎﻧﺪارد و اﺻﻼح ﺷﺪه ﻣﯽ ﺑﺎﺷﺪ.
ﻣﻮاد و روش ﺑﻪ ، ﻫﺎ: در اﯾﻦ ﭘﮋوﻫﺶ ﻣﻨﻈﻮر ارزﯾﺎﺑﯽ ﺗﺨﺮﯾﺐ اراﺿﯽ و ﺗﻬﯿﻪ ﻧﻘﺸﻪ آن در ﺣﻮﺿﻪ ﺳﯿﺎﻫﭙﻮش، از ﻣﺪل ﻣﺪاﻟﻮس اﺳﺘﺎﻧﺪارد و اﺻﻼح ﺷﺪه اﺳﺘﻔﺎده ﺷﺪ. ﺑﻪ اﯾﻦ ﻣﻨﻈﻮر ﭼﻬﺎر ﻣﻌﯿﺎر (ﮐﯿﻔﯿﺖ ﺧﺎك، اﻗﻠﯿﻢ، ﭘﻮﺷﺶ ﮔﯿﺎﻫﯽ و ﻣﺪﯾﺮﯾﺖ و ﺳﯿﺎﺳﺖ) ﮐﻪ در ﺑﯿﺎﺑﺎن زاﯾﯽ ﻣﻨﻄﻘﻪ ﻣﺆﺛﺮ ﺑﻮدﻧﺪ، اﻧﺘﺨﺎب ﮔﺮدﯾﺪ .ﺑﺮاي ﻫﺮ ﮐﺪام از ﻣﻌﯿﺎرﻫﺎ در ﻣﺪل ﻣﺪاﻟﻮس ﺷﺎﺧﺺ ﻫﺎﯾﯽ ﺗﻌﺮﯾﻒ ﺷﺪه اﺳﺖ .ﻻﯾﻪ ﻫﺎي اﻃﻼﻋﺎﺗﯽ ﺷﺎﺧﺺ ﻫﺎي ﻣﺮﺑﻮط ﺑﻪ ﻫﺮ ﯾﮏ از ﻣﻌﯿﺎرﻫﺎ ﺑﺎ اﺳﺘﻔﺎده از ﺳﺎﻣﺎﻧﻪ اﻃﻼﻋﺎت ﺟﻐﺮاﻓﯿﺎﯾﯽ ﺗﻬﯿﻪ ﺷﺪ .اﯾﻦ اﻃﻼﻋﺎت ﺑﺮ اﺳﺎس روش ﻣﺪاﻟﻮس اﻣﺘﯿﺎزدﻫﯽ ﺷﺪه و از ﻣﯿﺎﻧﮕﯿﻦ ﻫﻨﺪﺳﯽ ﺷﺎﺧﺺ ﻫﺎي ﻫﺮ ﯾﮏ از ﻣﻌﯿﺎرﻫﺎ، ﻧﻘﺸﻪ ﻧﻬﺎﯾﯽ وﺿﻌﯿﺖ ﻫﺮ ﻣﻌﯿﺎر ﺗﻬﯿﻪ و از ﻣﯿﺎﻧﮕﯿﻦ ﻫﻨﺪﺳﯽ ﻣﻌﯿﺎرﻫﺎ، ﻧﻘﺸﻪ ﺣﺴﺎﺳﯿﺖ ﺑﻪ ﺑﯿﺎﺑﺎن زاﯾﯽ منتقه تهيه گرديد.
ﯾﺎﻓﺘﻪ ﻫﺎ: ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﮐﻪ دو ﻣﻌﯿﺎر ﮐﯿﻔﯿﺖ ﻣﺪﯾﺮﯾﺖ و ﮐﯿﻔﯿﺖ اﻗﻠﯿﻢ ﺑﻪ ﺑﯿﺶ1/91 و 1/62 ﺗﺮﺗﯿﺐ ﺑﺎ ﻣﺘﻮﺳﻂ وزﻧﯽ ﺗﺮﯾﻦ ﺗﺄﺛﯿﺮ را در ﺑﯿﺎﺑﺎن زاﯾﯽ ﻣﻨﻄﻘﻪ داﺷﺘﻪ ، در ﮐﻼس ﻣﺘﻮﺳﻂ و ﻣﻌﯿﺎر ﮐﯿﻔﯿﺖ ﭘﻮﺷﺶ 1/39 اﻧﺪ .ﻣﻌﯿﺎر ﮐﯿﻔﯿﺖ ﺧﺎك ﺑﺎ ﻣﺘﻮﺳﻂ وزﻧﯽ ، در ﮐﻼس ﺑﺎ ﮐﯿﻔﯿﺖ ﺑﺎﻻ ﻗﺮار دارد. از اﯾﻦ 1/41ﮔﯿﺎﻫﯽ ﺑﺎ ﻣﺘﻮﺳﻂ وزﻧﯽ رو، ﻣﻨﺎﺳﺐ ﺗﺮﯾﻦ ﻣﻌﯿﺎر، ﮐﯿﻔﯿﺖ ﭘﻮﺷﺶ ﮔﯿﺎﻫﯽ ﻣﯽ باشد.ﻣﯿﺰان ﺷﺎﺧﺺ ﺑﯿﺎﺑﺎن زاﯾﯽ ﺑﺮاي ﻣﻨﻄﻘﻪ ﻣﻮرد ﺑﺮرﺳﯽ در ﻣﺪل ﻣﺪاﻟﻮس اﺳﺘﺎﻧﺪارد و ﻣﺪاﻟﻮس اﺻﻼح ﺷﺪه ﺑﻪ ﺗﺮﺗﯿﺐ ﺑﻪ1/38 ﺗﺎ 1/76 و 1/37 ﺗﺎ 1/93 دﺳﺖ آﻣﺪ .در ﻫﺮ دو روش ﮐﻞ ﻣﻨﻄﻘﻪ ﻣﻄﺎﻟﻌﺎﺗﯽ در ﮐﻼس ﺑﺤﺮاﻧﯽ ﺑﯿﺎﺑﺎن زاﯾﯽ ﻗﺮار ﮔﺮﻓﺖ .
ﻧﺘﯿﺠﻪ ﮔﯿﺮي: از ﺑﯿﻦ ﻣﻌﯿﺎرﻫﺎي ﻣﻮرد ﻣﻄﺎﻟﻌﻪ، ﻣﻌﯿﺎرﻫﺎي ﻣﺪﯾﺮﯾﺖ و اﻗﻠﯿﻢ ﺑﻪ ﻋﻨﻮان ﻧﺎﻣﻨﺎﺳﺐ ﺗﺮﯾﻦ و ﻣﻌﯿﺎر ﮐﯿﻔﯿﺖ ﭘﻮﺷﺶ ﮔﯿﺎﻫﯽ ﺑﻪ ﻋﻨﻮان ﻣﻨﺎﺳﺐ ﺗﺮﯾﻦ ﻣﻌﯿﺎر ﻣﺸﺨﺺ ﺷﺪﻧﺪ.ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﯾﺎﻓﺘﻪﻫﺎ وﺿﻌﯿﺖ ﺑﯿﺎﺑﺎنزاﯾﯽ در ﻣﻨﻄﻘﻪ ﺷﺪﯾﺪ ﻣﯽ ﺑﺎﺷﺪ، ﺑﻪ ﻃﻮري ﮐﻪ در روش ﻣﺪاﻟﻮس اﺳﺘﺎﻧﺪارد و اﺻﻼح ﺷﺪه ﺑﻪ ترتيب 90/1 و 99/2 درصد ازمنطقه مطالعاتي ،در كلاس بحراني شديد( C3) قرار گرفته است كه نيازمند توجه و مديريت هرچه بيش تر سازمان هاي مربوط و اعمال برنامه عملي پايش و مهار بحران بيابان زايي براي اصلاح شاخص هاي يادشده مي باشد .
چكيده لاتين :
Background and Objectives: Nowadays, land degradation is a serious problem in many parts of the world. Land degradation occurs as a result of various factors including climatic change, improper land use and management in arid, semi-arid and dry sub-humid areas. It has been recognized as a major socioeconomic, social and environmental problem in many countries of the world. Various models are provided in order to assess desertification in the world. It seems that the MEDALUS model has apparent advantages compared to the other ones, such as easy style, data accessibility and taking geometric mean. The objectives of this study were to mapping and quantitative evaluation of land degradation in Siyahpoush catchment using MEDALUS and adjusted MEDALUS model.
Materials and Methods: In this study, MEDALUS and adjusted MEDALUS models were applied to desertification assessment and mapping in Siyahpoush catchment. For this purpose, four important criteria (soil quality, climate, vegetation cover, management and policy) which were effective on desertification have been selected. Indices for each criterion are defined in the MEDALUS model. Index layers for each criterion were prepared using GIS. These indices were ranked in accordance with MEDALUS model. The geometric mean was then calculated and map was produced for each criterion. Land degradation map of the study area was finally prepared using the geometric mean criteria.
Results: The result showed that management quality and climate quality criteria with a geometric average of 1.91 and 1.62 have played the most important role in sensitivity of the area to desertification. Soil quality criterion with a geometric average of 1.39 and vegetation quality criterion with a geometric average of 1.41 were classified in moderate and high quality, respectively. Therefore, vegetation quality was determined as the most appropriate criterion. The ESAI index for MEDALUS and adjusted MEDALUS model ranged 1.38 to 1.79 and 1.37 to 1.93, respectively. This means that all area is located in critical class of desertification.
Conclusion: The management and climate quality were identified as the most inappropriate criteria and vegetation quality was found as the most appropriate criterion. According to the obtained results, the study area is classified as critical class by ESAs model, so that 90.1% and 99.2% of the study area is located in the severe critical sub-class (C3) whit MEDALUS and adjusted MEDALUS model, respectively. However, implementing management policies would help to restrain this phenomenon at field or regional level. In addition, monitoring of land degradation needs to be considered that have involved more effective indices in this region.
