بررسي اثر خشكسالي بر منابع آب استان كرمانشاه با استفاده از تصاوير ماهواره اي TRMM

Investigation of the effect of drought on water resources using TRMM satellite imagery in Kermanshah Province

ﻣﻄﺎﻟﻌﻪ ﺗﺄﺛﯿﺮات ﺧﺸﮑﺴﺎﻟﯽ ﺑﺮ ﻣﻨﺎﺑﻊ آﺑﯽ در ﮐﺸﻮر اﯾﺮان و ﺑﻪ وﯾﮋه در ﻧﻮاﺣﯽ ﮐﻮﻫﺴﺘﺎﻧﯽ ﺑﻪدﻟﯿﻞ ﻋﺪم ﭘﺮاﮐﻨﺶ ﻣﻨﺎﺳﺐ اﯾﺴﺘﮕﺎه، ﻧﺒﻮد داده ﻫﺎي ﻃﻮﻻﻧﯽ ﻣﺪت و ﻧﻮاﺣﯽ ﻓﺎﻗﺪ آﻣﺎر، ﻫﻤﻮاره ﺑﺎ ﻣﺸﮑﻼﺗﯽ ﻣﻮاﺟﻪ اﺳﺖ. از اﯾﻦ رو، ﻫﺪف اﺻﻠﯽ اﯾﻦ ﭘﮋوﻫﺶ، ﺑﺮرﺳﯽ ﺧﺸﮑﺴﺎﻟﯽ ﻫﺎي اﺳﺘﺎن ﮐﺮﻣﺎﻧﺸﺎه و ﺗﺄﺛﯿﺮ آن ﺑﺮ ﻣﻨﺎﺑﻊ آﺑﯽ ﺑﺎ اﺳﺘﻔﺎده از داده ﻫﺎي ﻣﺎﻫﻮاره اي TRMM و ﻫﻤﭽﻨﯿﻦ، ارزﯾﺎﺑﯽ دﻗﺖ آن ﻫﺎ در ﻣﻘﺎﺑﻞ دادهﻫﺎي اﯾﺴﺘﮕﺎه ﻫﺎي ﺳﯿﻨﻮﭘﺘﯿﮏ اﺳﺘﺎن ﮐﺮﻣﺎﻧﺸﺎه اﺳﺖ. ﺑﺮاي رﺳﯿﺪن ﺑﻪ اﯾﻦ ﻣﻨﻈﻮر، از روش ﻫﺎي آﻣﺎري و ﺳﻨﺠﺶ از دور اﺳﺘﻔﺎده ﺷﺪ. داده ﻫﺎي ﻣﻮرد اﺳﺘﻔﺎده ﺷﺎﻣﻞ داده ﻫﺎي ﺑﺎرش 42 ﻧﻘﻄﻪ ﻣﺪل TRMM ﺑﺎ دﻗﺖ ﻣﮑﺎﻧﯽ 0/25× 0/25 درﺟﻪ ﺟﻐﺮاﻓﯿﺎﯾﯽ، داده ﻫﺎي ﺑﺎرش اﯾﺴﺘﮕﺎه ﻫﺎي زﻣﯿﻨﯽ اﺳﺘﺎن ﮐﺮﻣﺎﻧﺸﺎه ﻃﯽ دوره 15 ﺳﺎﻟﻪ 2000-2014 و داده ﻫﺎي دﺑﯽ ﭼﺸﻤﻪ ﻫﺎي ﮐﺎرﺳﺘﯽ اﯾﻦ اﺳﺘﺎن اﺳﺖ. ارزﯾﺎﺑﯽ دﻗﺖ داده ﻫﺎي دو ﭘﺎﯾﮕﺎه داده ﺑﺎ اﺳﺘﻔﺎده از آﻣﺎره ﻫﺎي NRMSE ،Slope ،IA ،EF ،R2 ،R و Bias در ﻣﺤﯿﻂ ﻧﺮم اﻓﺰار MATLAB اﻧﺠﺎم ﺷﺪه اﺳﺖ. ارزﯾﺎﺑﯽ دﻗﺖ داده ﻫﺎي ﻣﺪل TRMM در ﻣﻘﺎﺑﻞ داده ﻫﺎي ﺑﺎرش ﺛﺒﺖ ﺷﺪه اﯾﺴﺘﮕﺎه ﻫﺎي زﻣﯿﻨﯽ در ﻣﻘﯿﺎس ﻣﺎﻫﺎﻧﻪ ﻧﺸﺎن داد ﮐﻪ داده ﻫﺎي اﯾﻦ ﻣﺎﻫﻮاره در ﺳﻄﺢ اﺳﺘﺎن از دﻗﺖ ﺑﺴﯿﺎر ﻣﻨﺎﺳﺒﯽ ﺑﺮﺧﻮردارﻧﺪ و 70 ﺗﺎ 80 درﺻﺪ وارﯾﺎﻧﺲ ﺑﺎرش داده ﻫﺎي اﯾﺴﺘﮕﺎﻫﯽ، ﺑﻪ ﮐﻤﮏ داده ﻫﺎي ﺑﺎرش اﯾﻦ ﻣﺎﻫﻮاره ﺗﺒﯿﯿﻦ ﻣﯽ ﺷﻮﻧﺪ. ﻫﻤﭽﻨﯿﻦ، ﻣﻘﺪار اﻧﺤﺮاف داده ﻫﺎي ﻣﺎﻫﻮاره از داده ﻫﺎي اﯾﺴﺘﮕﺎﻫﯽ ﺑﺴﯿﺎر ﻧﺎﭼﯿﺰ و ﮐﻤﺘﺮ از 10 ﻣﯿﻠﯽ ﻣﺘﺮ اﺳﺖ. ﭘﺎﯾﺶ ﺧﺸﮑﺴﺎﻟﯽ در ﺳﻄﺢ اﺳﺘﺎن ﮐﺮﻣﺎﻧﺸﺎه ﺑﺎ اﺳﺘﻔﺎده از داده ﻫﺎي TRMM و ﺷﺎﺧﺺ SPI در ﻣﻘﯿﺎس ﻫﺎي ﻣﺎﻫﺎﻧﻪ، ﻓﺼﻠﯽ و ﺳﺎﻻﻧﻪ ﻧﺸﺎن داد ﮐﻪ ﻣﻌﻤﻮﻻ ﻓﺮاواﻧﯽ ﺧﺸﮑﺴﺎﻟﯽ در اﯾﻦ اﺳﺘﺎن ﺑﯿﺶ از ﺗﺮﺳﺎﻟﯽ اﺳﺖ، اﻣﺎ ﺷﺪت دوره ﻫﺎي ﺧﺸﮏ ﮐﻤﺘﺮ از دوره ﻫﺎي ﻣﺮﻃﻮب اﺳﺖ و ﭼﻨﺪ دوره ﺧﺸﮏ ﺑﻪوﺳﯿﻠﻪ ﯾﮏ دوره ﻣﺮﻃﻮب ﺟﺒﺮان ﻣﯽ ﺷﻮد. ﺗﻮزﯾﻊ زﻣﺎﻧﯽ ﻧﻤﺮات اﺳﺘﺎﻧﺪاردﺷﺪه ﺑﺎرش ﻧﯿﺰ ﻧﺸﺎن داد، دوره ﻫﺎي ﻣﺮﻃﻮب ﻋﻤﺪﺗﺎ در اﺑﺘﺪاي دوره ﻣﻄﺎﻟﻌﺎﺗﯽ و دوره ﻫﺎي ﺧﺸﮏ در اﻧﺘﻬﺎي دوره ﻣﻄﺎﻟﻌﺎﺗﯽ از ﺗﻤﺮﮐﺰ ﺑﯿﺸﺘﺮي ﺑﺮﺧﻮردارﻧﺪ. از اﯾﻦ رو، ﻣﻘﺪار ﺑﺎرش اﺳﺘﺎن در ﺣﺎل ﮐﺎﻫﺶ و ﺳﻬﻢ ﺑﺎرش ﻫﺎي ﺑﻬﺎري ﻧﺴﺒﺖ ﺑﻪ ﺑﺎرش ﻫﺎي ﭘﺎﯾﯿﺰه و زﻣﺴﺘﺎﻧﻪ در ﺣﺎل اﻓﺰاﯾﺶ اﺳﺖ. ﻧﺘﺎﯾﺞ ﺣﺎﺻﻞ از ﻣﻘﺎﯾﺴﻪ داده ﻫﺎي دﺑﯽ و ﺑﺎرش و ﺑﺮرﺳﯽ اﺛﺮات ﺧﺸﮑﺴﺎﻟﯽ ﺑﺮ ﻣﻨﺎﺑﻊ آب ﻧﺸﺎن داد، ارﺗﺒﺎط ﺑﺴﯿﺎر ﻗﻮي ﺑﯿﻦ ﺑﺎرش و دﺑﯽ ﭼﺸﻤﻪ ﻫﺎي ﮐﺎرﺳﺘﯽ اﺳﺘﺎن ﮐﺮﻣﺎﻧﺸﺎه وﺟﻮد دارد و ﺧﺸﮑﺴﺎﻟﯽ ﻫﺎي ﺷﺪﯾﺪ ﻫﯿﺪروﻟﻮژﯾﮏ ﺑﻪ ﺷﺪت ﻣﺘﺄﺛﺮ از ﮐﺎﻫﺶ رﯾﺰش ﻫﺎي ﺟﻮي اﺳﺖ. ﺑﻪﻃﻮريﮐﻪ، ﻣﻘﺪار ﻫﻤﺒﺴﺘﮕﯽ ﺑﯿﻦ ﺑﺎرش و دﺑﯽ ﭼﺸﻤﻪﻫﺎي ﮐﺎرﺳﺘﯽ ﻣﻨﺘﺨﺐ ﺑﯿﻦ 0/77 ﺗﺎ 0/88 اﺳﺖ و در ﺑﻬﺘﺮﯾﻦ ﺣﺎﻟﺖ، ﻣﻘﺪار ﺿﺮﯾﺐ ﺗﻌﯿﯿﻦ ﺑﺮاي اﯾﺴﺘﮕﺎه رواﻧﺴﺮ ﺑﻪ 0/77 ﻣﯽرﺳﺪ.

The effects of drought on water resources in mountainous areas in Iran, is very difficult, due to lack of proper distribution of the station as well as lack of long-term data. The main objective of this study is to investigate the droughts in Kermanshah. The data used included the precipitation data of 42 points of the TRMM model with a spatial accuracy of 0.25 × 0.25 degrees, precipitation data of ground stations for the 15-year period (2014-2000) and the discharge of karst springs. The accuracy of data from two databases was evaluated by using R, R2, EF, IA, Slope, NRMSE and Bias statistics in the MATLAB software. The evaluation of the TRMM model's accuracy in comparison with the recorded rainfall data of ground stations on a monthly scale showed that the satellite data is very accurate and 70 to 80 percent of the precipitation data variance is explained by satellite rainfall data. Also, the amount of satellite data deviation from the station data is negligible and less than 10 mm. Drought monitoring using TRMM data and SPI index in monthly, seasonal and annual measurements showed that the frequency of drought in this province is usually more than wet, but the severity of the dry periods is less than wet periods and some dry periods are compensated by a wet period. The time distribution of SPI showed that wet and dry periods are more concentrated at the beginning and the end of the study respectively. Therefore, rainfall is decreasing and the contribution of spring rainfall is rising relative to fall and winter rainfall. The correlation coefficient (R) between precipitation and discharge of selected karst springs is between 0.77 and 0.88 where the highest coefficient of determination (R2 = 0.77) occurred in Ravansar station.