توسعه مدل دراستيك اصلاح شده DRAST-VUL براي تعيين آسيب‌پذيري آبخوان در مناطق شهري

Modifying DRASTIC Model DRAST-VUL to determine groundwater vulnerability in an urban aquifer

در آﺑﺨﻮانﻫﺎي ﻣﻨﺎﻃﻖ ﺷﻬﺮي، ﺑﻪ دﻟﯿﻞ وﺟﻮد ﻣﻨﺎﺑﻊ ﻣﺨﺘﻠﻒ آﻻﯾﻨﺪه، اﺣﺘﻤﺎل آﻟﻮدﮔﯽ ﻣﻨﺎﺑﻊ آب زﯾﺮزﻣﯿﻨﯽ ﺑﺎﻻﺳﺖ، ﻟﺬا، ﺑﺮرﺳﯽ آﺳﯿﺐﭘﺬﯾﺮي ﻣﻨﺎﺑﻊ آب زﯾﺮزﻣﯿﻨﯽ ﻣﯽﺗﻮاﻧﺪ در ﺗﻌﯿﯿﻦ ﻧﻘﺎط آﺳﯿﺐﭘﺬﯾﺮ و ﺣﺴﺎس آﺑﺨﻮان ﺑﺴﯿﺎر ﻣﻮﺛﺮ ﺑﺎﺷﺪ. ﻫﺪف از اﯾﻦ ﻣﻄﺎﻟﻌﻪ، اراﺋﻪ و ﺗﻮﺳﻌﻪ ﻣﺪل دراﺳﺘﯿﮏ اﺻﻼح ﺷﺪه ﺑﺮاي ﺗﻌﯿﯿﻦ آﺳﯿﺐ ﭘﺬﯾﺮي آﺑﺨﻮان در ﻣﻨﺎﻃﻖ ﺷﻬﺮي اروﻣﯿﻪ اﺳﺖ. ﺑﺮاي اﯾﻦ ﻣﻨﻈﻮر، ﭘﺎراﻣﺘﺮﻫﺎي ﺑﺎ ﺗﺎﺛﯿﺮ ﮐﻢ، ﺷﯿﺐ و ﻣﺤﯿﻂ آﺑﺨﻮان از ﻣﺪل دراﺳﺘﯿﮏ ﺣﺬف و در ﻋﻮض ﭘﺎراﻣﺘﺮﻫﺎي ﮐﺎرﺑﺮي اراﺿﯽ، ﺷﺎﺧﺺ ﺷﻬﺮﻧﺸﯿﻨﯽ، ارزش و ﺑﻬﺎي آب و ﻣﻨﺎﺑﻊ آﻻﯾﻨﺪه دﺧﯿﻞ در آﻟﻮدﮔﯽ ﺑﻪ ﻣﺪل اﺿﺎﻓﻪ و ﻻﯾﻪﻫﺎي ﺗﻐﺬﯾﻪ و ﺗﺎﺛﯿﺮ زون ﻏﯿﺮاﺷﺒﺎع اﺻﻼح ﺷﺪ. ﻧﺘﺎﯾﺞ ﺣﺎﺻﻞ از ﻣﺪل دراﺳﺘﯿﮏ اﺻﻼح ﺷﺪه DRAST-VUL در ﻣﻨﻄﻘﻪ ﻣﻮرد ﻣﻄﺎﻟﻌﻪ ﻧﺸﺎن ﻣﯽ دﻫﺪ ﮐﻪ در ﺑﯿﺸﺘﺮ ﻣﻨﺎﻃﻖ رﯾﺴﮏ آﻟﻮدﮔﯽ ﮐﻢ ﺗﺎ ﻣﺘﻮﺳﻂ ﺑﻮده، وﻟﯽ در 29 درﺻﺪ از ﻣﺤﺪوده ﻣﻮرد ﻣﻄﺎﻟﻌﻪ ﺑﻪ دﻟﯿﻞ ﻓﻌﺎﻟﯿﺖ ﻫﺎي ﮐﺸﺎورزي، ﺻﻨﻌﺘﯽ و ﻋﻤﻖ ﮐﻢ آب زﯾﺮزﻣﯿﻨﯽ آﺳﯿﺐ ﭘﺬﯾﺮي ﺑﺎﻻﺳﺖ. ﺑﺮ اﺳﺎس ﻧﺘﺎﯾﺞ ﺣﺎﺻﻠﻪ، ﺑﯿﺸﺘﺮﯾﻦ ﺣﺴﺎﺳﯿﺖ ﻣﺪل ﻧﺴﺒﺖ ﺑﻪ ﭘﺎراﻣﺘﺮ ﻣﻨﺎﺑﻊ آﻻﯾﻨﺪه، ﮐﺎرﺑﺮي اراﺿﯽ و ﻣﻨﻄﻘﻪ ﻏﯿﺮاﺷﺒﺎع ﺑﻮده، ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ زﯾﺎد ﺑﻮدن ﺳﻄﻮح ﻧﻔﻮذﻧﺎﭘﺬﯾﺮ در ﻣﻨﺎﻃﻖ ﺷﻬﺮي، ﺣﺴﺎﺳﯿﺖ ﻣﺪل ﺑﻪ ﭘﺎراﻣﺘﺮﻫﺎي ﺗﻐﺬﯾﻪ ﺧﺎﻟﺺ، ﺿﺮﯾﺐ ﻗﺎﺑﻠﯿﺖ اﻧﺘﻘﺎل و ارزش و ﺑﻬﺎي آب ﮐﻢ اﺳﺖ. ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﻧﺘﺎﯾﺞ ﻣﺜﺒﺖ ﺣﺎﺻﻞ از ﺻﺤﺖﺳﻨﺠﯽ ﻣﺪل از ﻃﺮﯾﻖ ﻧﯿﺘﺮات، ﻣﺪل اراﺋﻪ ﺷﺪه ﻣﯽﺗﻮاﻧﺪ ﺑﻪ اﺑﺰار ﮐﺎرآﻣﺪ ﺑﺮاي ﺣﻔﺎﻇﺖ، ﭘﯿﺸﮕﯿﺮي و ﺑﻬﺮهﺑﺮداري ﺑﻬﯿﻨﻪ از ﻣﻨﺎﺑﻊ آب زﯾﺮزﻣﯿﻨﯽ در ﻣﻨﻄﻘﻪ ﻣﻮرد ﻣﻄﺎﻟﻌﻪ و ﻫﻤﭽﻨﯿﻦ، ﺑﻪ ﻋﻨﻮان ﯾﮏ ﻣﺪل آﺳﯿﺐ ﭘﺬﯾﺮي اﻟﮕﻮ، ﺑﺮاي ﺳﺎﯾﺮ آﺑﺨﻮان ﻫﺎي ﺷﻬﺮي اﺳﺘﻔﺎده ﺷﻮد.

Due to various sources of contamination in the urban aquifers, the potential for pollution of groundwater resources is high. Thus, the vulnerability of groundwater resources can be very effective in identifying vulnerabilities and sensitive groundwater aquifers. The aim of this study was to present a modified DRASTIC Model to determine groundwater vulnerability in Urmia urban aquifer. To this end, parameters with low impact such as slope and aquifer media were ignored from the DRASTIC Model. Instead, land use, urbanization index, water value and pollution sources were added to the model. Also, the impact of unsaturated zone media and recharge layers were corrected. Results of the modified DRAST-VUL Model in the study area demonstrate that in most areas, the risk of pollution is low to moderate and the vulnerability in 29% of study area is high due to agricultural and industrial activities and low groundwater depth. Considering the results, the vulnerability index is the most sensitive measure to the parameter of pollutant sources, land use and the unsaturated zone. The sensitivity of the model to recharge, transmissivity and water value parameters were low due to the increase of impermeable surface in urban area. Based on positive results obtained from model validation through nitrate, the proposed model can be considered as an effective tool for the protection, revention and optimal utilization of groundwater resources in the study area. Also, this vulnerability model can be used for other urban aquifers.