ﭘﺎﯾﺶ و ﻣﺪلﺳﺎزي ﺷﺪت ﺑﯿﺎﺑﺎنزاﯾﯽ ﺑﺎ اﺳﺘﻔﺎده ازﺗﺼﺎوﯾﺮ ﻣﺎﻫﻮاره ﻟﻨﺪﺳﺖ ﻣﻄﺎﻟﻌﻪ ﻣﻮردي ﺣﻮزه آﺑﺨﯿﺰ ﯾﺰدان آﺑﺎد زرﻧﺪ

Monitoring and Modeling of Desertification Intensity Using Landsat Satellite Images (Case Study of Yazdanabad-Zarand watershed)

ﭘﺪﯾﺪه ﺑﯿﺎﺑﺎنزاﯾﯽ در ﮔﺴﺘﺮه وﺳﯿﻊ اﻗﻠﯿﻤﯽ از ﻣﻨﺎﻃﻖ ﺧﺸﮏ و ﻧﯿﻤﻪﺧﺸﮏ ﺗﺎ ﻧﯿﻤﻪﻣﺮﻃﻮب ﺑﺮوز ﮐﺮده و در اﺛﺮ ﻋﻮاﻣﻞ ﻃﺒﯿﻌﯽ و ﻋﻤﻠﮑﺮد ﻧﺎدرﺳﺖ اﻧﺴﺎﻧﯽ اﯾﺠﺎد ﻣﯽﺷﻮد. ﺗﺨﺮﯾﺐ ﭘﻮﺷﺶ ﮔﯿﺎﻫﯽ ﻣﺮﺗﻌﯽ، ﮐﺸﺎورزي، ﺗﺨﺮﯾﺐ ﺧﺎك و ﻧﺎﻣﻨﺎﺳﺐ ﺷﺪن ﮐﯿﻔﯿﺖ ﻣﻨﺎﺑﻊ آﺑﯽ، ﺣﺎﺻﻞ اﯾﻦ ﭘﺪﯾﺪه ﻣﯽﺑﺎﺷﺪ. ﺣﻮزه آﺑﺨﯿﺰ ﯾﺰدانآﺑﺎد ﯾﮑﯽ از ﮐﺎﻧﻮنﻫﺎي ﻓﻌﺎل ﺑﯿﺎﺑﺎنزاﯾﯽ اﺳﺘﺎن ﮐﺮﻣﺎن اﺳﺖ و در ﻃﻮل زﻣﺎن ﺗﺤﺖ ﺗﺄﺛﯿﺮ ﻓﻌﺎﻟﯿﺖﻫﺎي اﻧﺴﺎﻧﯽ و ﺗﻐﯿﯿﺮات اﻗﻠﯿﻤﯽ ﻣﺨﺼﻮﺻﺎً ﺧﺸﮏﺳﺎﻟﯽ ﺑﻮده اﺳﺖ. ﻫﺪف از اﯾﻦ ﺗﺤﻘﯿﻖ ﺑﺮرﺳﯽ ﭘﺘﺎﻧﺴﯿﻞ ﺑﯿﺎﺑﺎنزاﯾﯽ ﺣﻮزه آﺑﺨﯿﺰ ﯾﺰدانآﺑﺎد زرﻧﺪ ﺑﺎ اﺳﺘﻔﺎده از دادهﻫﺎي رﻗﻮﻣﯽ ﻣﺎﻫﻮارهاي در ﺑﺎزه زﻣﺎﻧﯽ 20 ﺳﺎﻟﻪ از ﺳﺎل 1379 ﺗﺎ 1399 ﻣﯽﺑﺎﺷﺪ. در اﯾﻦ راﺳﺘﺎ اﺑﺘﺪا ﻧﻘﺸﻪ ﮐﺎرﺑﺮي اراﺿﯽ ﺑﺮاي ﺳﺎل 1379 و 1399 ﺗﻬﯿﻪ ﺷﺪ. از دادهﻫﺎي رﻗﻮﻣﯽ ﻟﻨﺪﺳﺖ ﺑﺮاي ﺑﺮرﺳﯽ راﺑﻄﻪ ﺑﯿﻦ ﺷﺎﺧﺺ ﭘﻮﺷﺶ ﮔﯿﺎﻫﯽ SAVI و ﺷﺎﺧﺺ اﻗﻠﯿﻤﯽ آﻟﺒﺪو اﺳﺘﻔﺎده ﺷﺪ. درﻧﻬﺎﯾﺖ ﺑﺎ اﺳﺘﻔﺎده از اﯾﻦ راﺑﻄﻪ، ﺷﺎﺧﺺ ﺑﯿﺎﺑﺎنزاﯾﯽ DDI در ﮐﻼسﻫﺎي ﻣﺨﺘﻠﻒ ﺑﯿﺎﺑﺎنزاﯾﯽ ﺗﻬﯿﻪ ﺷﺪ. ﻧﺘﺎﯾﺞ اﯾﻦ ﺗﺤﻘﯿﻖ ﻧﺸﺎن داد ﮐﻪ در ﺳﺎل 1379 ﺣﺪود 83 درﺻﺪ از ﺣﻮزه آﺑﺨﯿﺰ ﯾﺰدانآﺑﺎد را اراﺿﯽ ﻣﺮﺗﻌﯽ ﺗﺸﮑﯿﻞ دادهاﻧﺪ ﮐﻪ ﻣﺴﺎﺣﺖ آﻧﻬﺎ در ﻃﻮل اﯾﻦ ﺑﺎزه زﻣﺎﻧﯽ از 48124/7 ﻫﮑﺘﺎر ﺑﻪ 46095/6 ﻫﮑﺘﺎر ﮐﺎﻫﺶ داﺷﺘﻪ اﺳﺖ. اﯾﻦ ﮐﺎﻫﺶ در ﺣﺎﻟﯽ اﺳﺖ ﮐﻪ ﻣﺴﺎﺣﺖ ﮐﺎرﺑﺮيﻫﺎي اراﺿﯽ ﺷﻮرهزار، اراﺿﯽ ﮐﺸﺎورزي و ﻣﻨﺎﻃﻖ ﻣﺴﮑﻮﻧﯽ و اﻧﺴﺎنﺳﺎﺧﺖ ﺑﻪ ﺗﺮﺗﯿﺐ ﺣﺪود 831/5 ،91/4 و 1106/3 ﻫﮑﺘﺎر اﻓﺰاﯾﺶ داﺷﺘﻪاﻧﺪ. ﺑﺮرﺳﯽ ﻣﺘﻮﺳﻂ ﺳﺎﻻﻧﻪ دو ﺷﺎﺧﺺ SAVI و آﻟﺒﺪو ﻧﺸﺎن داد ﮐﻪ در ﺣﻮزه آﺑﺨﯿﺰ ﯾﺰدانآﺑﺎد درﻣﺠﻤﻮع ﺷﺎﺧﺺ SAVI روﻧﺪ ﮐﺎﻫﺸﯽ و ﺷﺎﺧﺺ آﻟﺒﺪو روﻧﺪ اﻓﺰاﯾﺸﯽ داﺷﺘﻪ اﺳﺖ. ﺑﺮرﺳﯽ ﮐﻼسﻫﺎي ﺑﯿﺎﺑﺎنزاﯾﯽ ﺣﺎﺻﻞ از ﺷﺎﺧﺺ DDI در ﺳﺎل 1379 و 1399 ﻧﺸﺎن داد ﮐﻪ ﺑﯿﺶ از 88 درﺻﺪ از اﯾﻦ دﺷﺖ در ﮐﻼسﻫﺎي ﺑﺴﯿﺎر ﺷﺪﯾﺪ و ﺷﺪﯾﺪ ﺑﯿﺎﺑﺎنزاﯾﯽ ﻗﺮارﮔﺮﻓﺘﻪ اﺳﺖ. اﯾﻦ ﻧﺘﺎﯾﺞ ﺣﺎﮐﯽ از آن اﺳﺖ ﮐﻪ اﯾﻦ ﻣﻨﻄﻘﻪ ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﺷﺮاﯾﻂ اﻗﻠﯿﻤﯽ و ﭘﻮﺷﺶ ﮔﯿﺎﻫﯽ ﺷﮑﻨﻨﺪه، ﺑﻪﺷﺪت ﺑﻪ ﺗﻐﯿﯿﺮات و ﺗﺨﺮﯾﺐ اراﺿﯽ ﺣﺴﺎس ﻣﯽﺑﺎﺷﺪ.

Desertification is in general surface degradation whose key nature reflects the weakening or loss of land potential for growing green plants (Fleskens & Stringer, 2014). This process refers to land degradation in arid and semiarid and arid and semi-humid areas that are affected by various factors, e.g., climatic changes and human activities (Guo, 2021). Desertification is one of the most serious threats to human life, which is more evident in arid regions. Arid regions constitute over 40% of land area and over 250 million people are affected by this phenomenon (Sivakumar, 2011). Changing vegetation cover is one of the key desertification analysis and assessment methods. Recent studies have employed various indices to study desertification. Accordingly, the present research aimed to present a desertification monitoring model based on a relationship between soiladjusted vegetation index (SAVI) and Albedo climatic index derived from the Landsat images over the 2000-2020 time interval