امكان‌سنجي جمع‌آوري آب باران در يك منطقه نيمه‌خشك استان فارس

Rainwater harvesting potential in a semi-arid region of Fars Province

اﺳﺘﺤﺼﺎل آب ﺑﺎران ﺑﺎ ﺳﺎﻣﺎﻧﻪﻫﺎي ﮐﻮﭼﮏ ﯾﮑﯽ از ﮔﺰﯾﻨﻪﻫﺎي ﺗﻮﺳﻌﻪ ﻣﻨﺎﺑﻊ آب در ﻣﻨﺎﻃﻖ ﺧﺸﮏ اﺳﺖ ﮐﻪ ﻣﯽﺗﻮاﻧﺪ ﺑﺨﺸﯽ از آب ﻣﻮرد ﻧﯿﺎز ﺑﺨﺶ ﮐﺸﺎورزي دﯾﻢ را ﺗﺄﻣﯿﻦ ﮐﻨﺪ. ﺑﺮاي اﻓﺰاﯾﺶ ﭘﺘﺎﻧﺴﯿﻞ اﺳﺘﺤﺼﺎل آب در ﺳﺎﻣﺎﻧﻪ ﮐﻮﭼﮏ ﻣﯽﺗﻮان اﻗﺪاﻣﺎﺗﯽ ﺑﺮاي اﻓﺰاﯾﺶ ﺗﻮﻟﯿﺪ رواﻧﺎب اﻧﺠﺎم داد. در اﯾﻦ ﭘﮋوﻫﺶ، اﺳﺘﻔﺎده از ﺗﯿﻤﺎرﻫﺎي ﺳﺎده اﯾﺠﺎد ﺟﻮي و ﭘﺸﺘﻪ، ﭘﻮﺷﺶ ﺧﺎك رس و ﺗﺮﮐﯿﺐ اﯾﻦ دو در ﮐﻨﺎر ﺗﯿﻤﺎر ﺷﺎﻫﺪ ﺑﻪﻣﻨﻈﻮر ﺑﺮرﺳﯽ رواﻧﺎب ﺗﻮﻟﯿﺪي در ﻗﺎﻟﺐ ﻃﺮح ﮐﺎﻣﻼ ﺗﺼﺎدﻓﯽ ﺑﺎ ﺳﻪ ﺗﮑﺮار و ﻃﯽ دو ﺳﺎل )1393 و 1394( در ﻣﻨﻄﻘﻪ زرﯾﻦدﺷﺖ اﺳﺘﺎن ﻓﺎرس ارزﯾﺎﺑﯽ ﺷﺪ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﮐﻪ ﻣﻨﻄﻘﻪ ﭘﺘﺎﻧﺴﯿﻞ اﺳﺘﺤﺼﺎل آب ﺑﺎران را دارد. ﺑﯿﺸﺘﺮﯾﻦ ﻣﻘﺪار ﺿﺮﯾﺐ رواﻧﺎب در ﺗﯿﻤﺎر ﺷﺎﻫﺪ و ﺑﻪ ﻣﻘﺪار 6/5 و 9/3 درﺻﺪ ﺑﻪﺗﺮﺗﯿﺐ در ﺳﺎل اول و دوم ﻣﺸﺎﻫﺪه ﺷﺪ. دﺳﺖﺧﻮردﮔﯽ ﺧﺎك ﺳﻄﺤﯽ )در ﺗﯿﻤﺎرﻫﺎي ﻏﯿﺮ از ﺷﺎﻫﺪ( ﺑﻪﻃﻮر ﻣﺘﻮﺳﻂ 11 و 14 درﺻﺪ رواﻧﺎب و ﺿﺮﯾﺐ رواﻧﺎب )ﺑﻪﺗﺮﺗﯿﺐ( را ﻧﺴﺒﺖ ﺑﻪ ﺷﺎﻫﺪ ﮐﺎﻫﺶ داد. آﺳﺘﺎﻧﻪ ﺑﺎرش ﺑﺮاي اﯾﺠﺎد رواﻧﺎب ﻃﯽ دو ﺳﺎل آزﻣﺎﯾﺶ در ﺗﯿﻤﺎر ﺷﺎﻫﺪ ﺣﺪود ﯾﮏ ﻣﯿﻠﯽﻣﺘﺮ ﺑﻮد. در ﺳﺎﯾﺮ ﺗﯿﻤﺎرﻫﺎ آﺳﺘﺎﻧﻪ ﺑﺎرش در اﯾﺠﺎد رواﻧﺎب در ﺳﺎل دوم ﮐﺎﻫﺶ ﯾﺎﻓﺖ. از ﻧﻈﺮ ﻣﻘﺪار و ﺿﺮﯾﺐ رواﻧﺎب و ﻧﯿﺰ آﺳﺘﺎﻧﻪ ﺑﺎرش در اﯾﺠﺎد رواﻧﺎب، ﺗﯿﻤﺎر ﺷﺎﻫﺪ در ﺳﺎﻣﺎﻧﻪ ﮐﻮﭼﮏ ﻗﺎﺑﻞ ﭘﯿﺸﻨﻬﺎد اﺳﺖ. ﻣﺴﺎﺣﺖ ﺳﺎﻣﺎﻧﻪ ﮐﻮﭼﮏ ﺑﯿﻦ ﺣﺪود 15 ﺗﺎ 150 ﻣﺘﺮ ﻣﺮﺑﻊ ﺑﺮاي ﺗﺄﻣﯿﻦ ﺑﻪﺗﺮﺗﯿﺐ 300 و 600 ﻣﯿﻠﯽﻣﺘﺮ ﻧﯿﺎز آﺑﯽ ﺑﺎ اﺣﺘﻤﺎل وﻗﻮع 50 و 67 درﺻﺪ ﺑﺎرﻧﺪﮔﯽ و راﻧﺪﻣﺎن ذﺧﯿﺮه 25 و 50 درﺻﺪ ﻣﺘﻐﯿﺮ ﺑﻮد. اﻟﺒﺘﻪ در واﻗﻊ ﻣﺴﺎﺣﺖ ﺳﺎﻣﺎﻧﻪ ﮐﻮﭼﮏ ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﻧﻮع ﻣﺤﺼﻮل ﻣﯽﺗﻮاﻧﺪ ﺑﻪ ﺻﻮرت اﻗﺘﺼﺎدي ﺗﻌﯿﯿﻦ ﺷﻮد.

Rainwater harvesting using micro-catchment is one of the water resources development options in arid regions that can partly supply water requirement of rain-fed agriculture. Some operations can be performed for increasing the harvesting rainwater in micro-catchment. In this study, the effect of simple treatments including furrowing, clay cover, furrowing and clay cover and control treatments on runoff production were investigated in the form of a complete randomize design with three replications during 2014 and 2015 in Zarrin-Dasht region of Fars Province. Results confirmed the potential of rainwater harvesting in the region. The highest runoff coefficient was observed in control treatment as 6.5 and 9.3% in 2014 and 2015, respectively. Disturbing of surface soil (in various treatments except control) led to average reduction of 11 and 14% runoff amount and coefficient, respectively compared to the control treatment. Threshold Precipitation for Runoff Production (TPRP) was 1 mm in control treatment during two years of the experiment. In other treatments TPRP values reduced in the second year. In view point of the runoff amount and coefficient and also TPRP, control treatment is recommendable in the region. The catchment area varied almost between 15 and 150 m2, respectively, for supply water requirement of 300 and 600 mm with rainfall occurrence probability of 0.50 and 0.67 and runoff storage efficiency of 25 and 50%. In fact, micro-catchment area can be economically determined with crop type.