كليدواژه :
ارزشگذاري اقتصادي , آب زيرزميني , دشت همدان- بهار , برنامه‌ريزي رياضي پويا , GAMS
چكيده فارسي :
آب به عنوان يكي از نهاده‌هاي اساسي در توليدات بخش كشاورزي، از جايگاه ممتازي در توسعه اين بخش برخوردار ميباشد. در دهه‌هاي اخير با رشد جمعيت، افزايش تقاضا براي محصولات كشاورزي و همچنين توسعه صنعت و كشاورزي، برداشت از منابع آب زيرزميني بعنوان مهم‌ترين تامين كننده آب در مناطق خشك و نيمه‌خشك نيز بطور چشمگيري افزايش يافته و منجر به پيشي گرفتن تقاضا بر عرضه منابع آب و ايجاد بحران در اغلب اين مناطق شده است. بي‌شك يكي از مهم‌ترين ابزارها در كنترل و مديريت تقاضاي منابع آب و كاهش بحران حاصل از آن، بهره گيري از ابزارهاي اقتصادي و لحاظ نمودن ارزش اقتصادي آب در فعاليت هاي كشاورزي بعنوان بزرگترين مصرف كننده آن ميباشد. مطالعه حاضر با هدف ارزشگذاري اقتصادي منابع آب زير زميني در دشت همدان- بهار با بهره‌گيري از الگوي برنامه‌ريزي پويا با استفاده از نرم‌افزار GAMS در سال زراعي 96-1395 ميباشد. بر اساس نتايج تحقيق ارزش اقتصادي آب زيرزميني به ازاي هر متر مكعب در چهار ناحيه دشت همدان-بهار شامل منطقه همدان 3543 ريال، منطقه لالجين 4538 ريال، منطقه بهار 4015 ريال و منطقه صالح‌آباد 3690 ريال محاسبه گرديد. همچنين بازده ناخالص حاصل از فعاليت هاي كشاورزي هر يك از مناطق به‌ترتيب، همدان (708/6887810)، لالجين (150/7148527)، بهار (755/4741399)، صالح‌آباد (005/3639706) ميليون ريال، بازده ناخالص كل مناطق (22417440) ميليون ريال و ميزان حجم آب مصرفي كل معادل 185629200 متر مكعب برآورد شد. بررسي و مقايسه ارزش اقتصادي برآورد شده با قيمت آب در نواحي مورد مطالعه نشان داد كه ارزش اقتصادي محاسبه شده هر متر مكعب آب بيشتر از قيمت فعلي آب در منطقه ميباشد، بطوريكه افزايش هزينه استفاده اين نهاده از طريق ابزارهاي مختلف سياستي نظير وضع قيمت آب مي‌تواند نقش موثري در كنترل بهره‌برداري و تخليه آبخوان داشته باشد.
چكيده لاتين :
Introduction
Our country is among regions facing water scarcity as a large area of Iran is located in arid and semi-arid climates. So, comparing the annual average rainfall with annual mean annual precipitation on the planet, the rainfall in Iran is less than one-third of the the world, in addition, the amount of rainfall and the area in which the agricultural main water user are located, does not match.The average annual rainfall in the world is about 850 mm and for Iran is about 250 mm, which is 40% less than the annual rainfall in Asia and approximately 33% less than the annual average of the world. The province of Hamedan has an area of 19493 square kilometers, located in the west of Iran between 33 degrees and 59 minutes to 35 degrees and 44 minutes north latitude, 47 degrees 47 minutes and 49 degrees, and 30 minutes east along the meridian of Greenwich.
This province area consists of four plains including bahar, Kabotrahang, Razan and Qahavand. The water catchment area of Hamedan-Bahar plain, also known as Siminrood, is located on the northern slopes of Alvand altitudes with an area of 2,243 square kilometers. The plain is 880 km2 and the surface area of the main aquifer is 468 km2 (Fig. 1).
Figure 1- Location of Hamedan-Bahar Plain and its Main Aquifer Area
This plain, based on climatic divisions, is located in a cold semisolid climate and has a cool, mountainous climate. The ban on the development of exploitation of groundwater in the Hamedan-Bahar plain has been applied since the year 1992 due to the negative balance and the susceptibility of supplying drinking water in the cities of Hamedan, Bahar, Laljin.
Around, 330 of the 609 plains in the country have been declared forbidden due to excessive perceptions. Hamedan-Bahar plain has been faced with a serious problem of water shortages due to excessive withdrawal of groundwater and negative water balance and the expansion of the area under irrigated production, as the annual rate of groundwater loss in this plain is 1 meter.
The main objectives of this research are to estimate the economic value of groundwater in the agricultural sector of Hamedan-Bahar plain and to determine the optimal cropping pattern in the studied area using the GAMS programming model and mathematical programming.
Eshraqi and colleague (7) on "Estimating the economic value of water in wheat production in Gorgan," have surveyed the demanders using a production function approach in 2012-2013. The results show that the economic value of water was estimated at 1564.5 Rials per cubic meter of water. Zeratakish (23), on "The economic valuation of water in the agricultural sector with an environmental approach in the Lichter plain", used a multidisciplinary mathematical programming approach. The economic value of water with a limit of 50, 60 and 70 percent was determined as 250, 1500 and 3050 rials, respectively.
Mohammad Ayattha Watto and Amin William (2016) addressed a positive mathematical planning approach for estimating and valuing groundwater in Pakistan. Their results indicate that limiting groundwater extraction forces farmers to irrigate the demand for water. Azavara et al. (2012), conducted a study using the PMP method to evaluate the economic irrigation water in three California regions. The analysis of the results showed that the final economic value of water is at least 2.5 times the price paid by the users.
Materials and Methods
In this study, a dynamic mathematical programming model was used to evaluate the economics of groundwater in the agricultural sector. The general form of the model is as follows:
