پتانسيل‏يابي اراضي ديم و تخصيص بهينه آب بين اراضي آبي و ديم (مطالعه موردي: دشت قزوين)

Identifying of Potential Rainfed Lands and Allocation of Optimum Irrigation Water to Irrigated vs Rainfed Lands (Case Study: Qazvin Plain)

براي آبياري تكميلي در اراضي ديم توجه به شرايط طبيعي اين اراضي و تامين آب ضروري است. هدف اين مطالعه پتانسيل‏يابي اراضي ديم دشت قزوين براي آبياري تكميلي و تخصيص بهينه منابع آب بين اراضي ديم و فارياب است. فرض شد سطح زير كشت آبي و ديم محصولات مختلف و همچنين كل حجم آب در دسترس در هر دهه بدون تغيير باقي خواهد ماند. نتايج مدل بهينه‏سازي نشان داد ميزان افزايش سود خالص با مديريت جديد تخصيص آب در صورت انتقال آب تا فواصل 2، 4، 6، 8، و 10 كيلومتري به‏ترتيب 2/11، 5/13، 2/19، 6/16، و 8/15 درصد است. همچنين جو يگانه گزينه براي كم‏آبياري در اراضي شبكه است. ميزان كم‏آبياري در مزارع جو 20 ميلي‌متر در دهه دوم آبان و 50 ميلي‌متر در دهه سوم ارديبهشت تعيين شد. همچنين عدس به‏ دليل ارزش اقتصادي بيشتر گزينه برتر براي آبياري تكميلي انتخاب شد. در دهه اول خرداد آبياري تكميلي به ميزان 75 ميلي‌متر بهترين تيمار در منطقه تعيين شد كه عملكرد عدس را از 1000 به 3000 كيلوگرم بر هكتار افزايش داد.

To properly manage to apply supplementary irrigation to rainfed lands, need arises as to take care of the dryland natural conditions, and as well to afford the needed irrigation water. The aim followed in the present study was to find out the potential available to supplementarily irrigate rainfed lands in the Plain of Qazvin, and also to find out how water can be proportioned to any of the rainfed or irrigatied lands. It was assumed that the area under cultivation of either system of cultivation, and as well total volume of available water would remain intact in any of the decades. Results of optimization model revealed an increased net benefit, under new water allocation management and in cases of water conveyance from distances 2000, 4000, 6000, 8000 and 10000 meters in a climatically normal year to be 11.1, 13.5, 19.2, 16.6 and 15.8 percent, respectively. Barley was figured out as the most proper choice for deficit irrigation in three climatic conditions. Depths of deficit irrigation to be applied were estimated as 20 mm in the first decade of November and 50 mm during the second decade of May. Lentil due to its high economic value was another first choice crop for supplementary irrigation. The best treatments for lentil supplementary irrigation rainfed fields amounted to 75 mm to be carried out in the third decade of May. Yield in lentil rainfed fields increased from 1000 to 3000 through application of the supplementary irrigation.