استفاده از مدل بيلان آب براي تعيين و پيش بيني زمان تاخير بين خشكسالي هواشناسي و هيدرولوژيكي

Determining and Estimating the Lag time between Meteorological and Hydrological Drought Using a Water Balance Model

ﻃﻮﻻﻧﯽ ﺷﺪن ﻣﺪت زﻣﺎن ﺧﺸﮑﺴﺎﻟﯽ ﻫﻮاﺷﻨﺎﺳﯽ ﻣﯽﺗﻮاﻧﺪ ﻣﻨﺠﺮ ﺑﻪ ﺷﺮوع ﺧﺸﮑﺴﺎﻟﯽ ﻫﯿﺪروﻟﻮژﯾﮏ ﺷﻮد. در اﯾﻦ ﭘﮋوﻫﺶ، ﺑﻪ ﺗﻌﯿﯿﻦ ﻓﺎﺻﻠﻪ زﻣﺎﻧﯽ ﻣﯿﺎن رﺧﺪاد اﯾﻦ دو ﻧﻮع ﺧﺸﮑﺴﺎﻟﯽ ﭘﺮداﺧﺘﻪ ﺷﺪه اﺳﺖ ﺗﺎ ﺑﺪﯾﻦوﺳﯿﻠﻪ ﺑﺘﻮان ﺑﺎ ﺷﺮوع ﺧﺸﮑﺴﺎﻟﯽ ﻫﻮاﺷﻨﺎﺳﯽ، زﻣﺎن رﺧﺪاد ﺧﺸﮑﺴﺎﻟﯽ ﻫﯿﺪروﻟﻮژﯾﮑﯽ را ﭘﯿﺶﺑﯿﻨﯽ ﮐﺮد. اﯾﻦ اﻣﺮ، ﮐﻤﮏ ﺧﻮاﻫﺪ ﮐﺮد ﮐﻪ ﺗﻤﻬﯿﺪات ﻻزم ﺑﺮاي ﻣﺪﯾﺮﯾﺖ ﺣﻮﺿﻪ را در ﺻﻮرت ﺑﺮوز ﮐﻤﺒﻮد آب از ﭘﯿﺶ ﻓﺮاﻫﻢ ﮐﺮد. ﺑﺮاي ﺗﻌﯿﯿﻦ و ﭘﯿﺶﺑﯿﻨﯽ ﻓﺎﺻﻠﻪ زﻣﺎﻧﯽ ﻣﯿﺎن دو ﻧﻮع ﺧﺸﮑﺴﺎﻟﯽ از ﻣﺪل ﺑﯿﻼن آب SWAT و ﺑﺮاي ﻣﻄﺎﻟﻌﻪ ﻣﻮردي از ﺣﻮزه آﺑﺨﯿﺰ ﻓﻮﻣﻨﺎت )ﺗﺎﻻب اﻧﺰﻟﯽ( در اﺳﺘﺎن ﮔﯿﻼن اﺳﺘﻔﺎده ﺷﺪ. ﺗﺤﻠﯿﻞ ﺣﺴﺎﺳﯿﺖ ﻣﺪل ﺑﯿﻼن، ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﺗﻮاﻧﺎﯾﯽ آن در ﺷﺒﯿﻪﺳﺎزي ﺟﺮﯾﺎن دراز ﻣﺪت رودﺧﺎﻧﻪ ﻫﺎي ﻣﻌﺮف در ﺣﻮﺿﻪ، ﺑﻪ روش OAT اﻧﺠﺎم ﺷﺪ و ﻧﺸﺎن داد ﮐﻪ از ﻣﯿﺎن ﭘﺎراﻣﺘﺮﻫﺎي ﻣﻮرد اﺳﺘﻔﺎده در ﻣﺪل SWAT، ﺳﻪ ﭘﺎراﻣﺘﺮ ﺷﻤﺎره ﻣﻨﺤﻨﯽ، آب ﻗﺎﺑﻞ دﺳﺘﺮس ﺧﺎك و ﻋﺎﻣﻞ ﺟﺒﺮان ﺗﺒﺨﯿﺮ در ﺧﺎك ﺑﻪﺗﺮﺗﯿﺐ ﺑﯿﺸﺘﺮﯾﻦ ﺗﺎﺛﯿﺮ را در ﺧﺮوﺟﯽ ﻣﺪل ﺑﺮاي ﻣﻮﺿﻮع ﻣﻮرد ﭘﮋوﻫﺶ دارا ﻣﯽ ﺑﺎﺷﻨﺪ. واﺳﻨﺠﯽ و اﻋﺘﺒﺎرﺳﻨﺠﯽ SWAT ﺑﺎ اﺳﺘﻔﺎده از ﻣﺪل SCH اﻧﺠﺎم ﺷﺪ و دﻗﺖ ﺷﺒﯿﻪﺳﺎزي ﺑﺎ اﺳﺘﻔﺎده از ﺷﺎﺧﺺﻫﺎي ﻧﺶ-ﺳﺎﺗﮑﻠﯿﻒ و ﺿﺮﯾﺐ ﻫﻤﺒﺴﺘﮕﯽ در دوره واﺳﻨﺠﯽ ﺑﻪﺗﺮﺗﯿﺐ 0/68 و 0/8 و در دوره اﻋﺘﺒﺎرﺳﻨﺠﯽ ﺑﻪﺗﺮﺗﯿﺐ 0/65 و 0/79 و ﻗﺎﺑﻞ ﻗﺒﻮل ﺑﺮآورد ﺷﺪ. ﺑﺎ داﺷﺘﻦ ﻣﺪل واﺳﻨﺠﯽ ﺷﺪه ﺑﯿﻼن، ﺑﺮاي ﻫﺮ ﺳﻨﺎرﯾﻮي اﺣﺘﻤﺎﻟﯽ در ﺧﺸﮑﺴﺎﻟﯽ ﻫﻮاﺷﻨﺎﺳﯽ وﺿﻌﯿﺖ ﺑﯿﻼن آﺑﯽ ﺣﻮﺿﻪ و ﻫﻤﭽﻨﯿﻦ، ﻓﺮﺻﺖ زﻣﺎﻧﯽ ﻣﻮﺟﻮد ﺑﺮاي رﺧﺪاد ﺧﺸﮑﺴﺎﻟﯽ ﻫﯿﺪروﻟﻮژﯾﮑﯽ ﻗﺎﺑﻞ ﭘﯿﺶﺑﯿﻨﯽ اﺳﺖ. ﺑﺮ اﺳﺎس ﻧﺘﺎﯾﺞ ﺑﻪدﺳﺖ آﻣﺪه ﺑﺎ اﺣﺘﻤﺎل ﺑﯿﺶ از 70 درﺻﺪ ﺗﺎﺧﯿﺮ زﻣﺎﻧﯽ ﯾﮏﻣﺎﻫﻪ و ﺑﻪﻫﻤﯿﻦ ﺗﺮﺗﯿﺐ ﺑﺎ اﺣﺘﻤﺎل ﺑﯿﺶ از 23 درﺻﺪ ﺗﺄﺧﯿﺮ زﻣﺎﻧﯽ دو ﻣﺎﻫﻪ ﺑﯿﻦ دو ﺧﺸﮑﺴﺎﻟﯽ ﻫﻮاﺷﻨﺎﺳﯽ و ﻫﯿﺪروﻟﻮژﯾﮑﯽ وﺟﻮد دارد.

Long meteorological drought can lead to the onset of hydrological drought. In this research, the lag time between the two types of drought was investigated for determining the hydrologic drought onset after realizing the climatological drought. This is a matter to provide managers with enough time for decision making before the occurrence of water shortage in the watershed. The SWAT water balance model was used to determine and predict the lag time between the two types of drought for Foomanat (Anzali wetland) watershed in Gilan province Due to the ability to simulate the long-term flow of representative rivers in the basin. The OAT method was employed for the sensitivity analysis of the water balance model. Among the parameters used in SWAT, three parameters including curve number, available water, and the evaporation compensation factor in the soil were recognized as the most effective parameters for the results of the model. Calibration and validation of SWAT were performed using SCH model. The calculated Nash-Sutcliff and correlation coefficient in estimating runoff as well as determining and predicting the lag time between the two types of drought by SWAT were acceptable. The Nash coefficient was obtained as 0.68 and 0.8 for calibration, and 0.65 and 0.79 for validation periods, respectively. Using the calibrated model, one can predict the water balance situation and the lag time between the onset of meteorological drought and the emerging hydrological drought in the watershed for any interested meteorological drought scenarios. Based on the results, the chance of having a one -month lag time, is more than 70 percent, while the chance of a 2-month lag time in the Foomanat watershed Anzali wetland) is more than 23 percent.