ارزیابی پایداری و تعیین الگوی کشت سیستم‌های زراعی با برنامه‌ریزی ریاضی چندهدفه

نویسندگان

چکیده

این مقاله به ارزیابی پایداری در سیستم زراعی دشت بجستان در استان خراسان رضوی و تعیین مناسب‌ترین الگوی کشت متناسب با آن می‌پردازد. برای تلفیق ابعاد سه‌گانه محیطی،‏ اقتصادی و اجتماعی،‏ دو معیار نسبی به عنوان شاخص‌های بررسی پایداری سیستم تعریف شدند. این دو معیار شامل حصول بیشترین عایدی اقتصادی و ایجاد بیشترین فرصت‌های اشتغال به ازای هر واحد مصرف آب،‏ هستند. بهینه‌سازی نسبت‌های «سود خالص به مصرف آب» و «ایجاد اشتغال به مصرف آب»،‏ با بهره‌گیری از مدل‌های برنامه‌ریزی ریاضی یک‌هدفه و چندهدفه کسری انجام شد. با هدف حداکثرسازی سود،‏ شاخص‌های پایداری سود به مصرف آب و اشتغال به مصرف آب در مدل کسری به‌ترتیب 3‎/17 و 0‎/19 درصد نسبت به مدل خطی افزایش داشت. با هدف حداکثرسازی اشتغال شاخص‌های پایداری بالا به‌ترتیب 2‎/25 و 1‎/22 درصد افزایش داشت. در رویکرد چندهدفه برنامه‌ریزی آرمانی،‏ شاخص اشتغال به مصرف آب در مدل کسری،‏ 4‎/32 درصد بیشتر از مدل خطی بود،‏ ولی نسبت اشتغال به مصرف آب 5‎/42 درصد افزایش نشان داد. در ادامه با مقایسه کارایی اقتصادی و اجتماعی هر واحد مصرف آب در سناریوهای مختلف،‏ مناسب‌ترین الگوهای کشت منطقه با توجه به منابع موجود آب و خاک و نیروی انسانی مشخص شد.

کلیدواژه‌ها


عنوان مقاله [English]

Stability evaluation and determining cropping pattern in agricultural systems by using multigoal mathematical programming

نویسندگان [English]

  • Mahdi Mahmoodi
  • Gholam-abbas Barani
  • Mohammad-Javad Khanjani
چکیده [English]

Stability of soil and water resources in agriculture, above all depends on the type of resource utilization and cropping pattern. Nowadays, maximization of factors such as income, job opportunities and minimization of costs as the economic and social aspects along with the limitations of arable land and water has attracted the attention of planners and managers of agricultural projects. One of the most important questions is the issue of sustainability, how to evaluate, measure and analyze sustainability? One of the methods to assess the stability is mathematical programming approaches. Application of this model for agricultural planning has a long history and a wide range. But using a particular type of this model to assess the sustainability, means the fractional model is a new topic. Lara and Stancu-Minasian (1999) examined the theoretical aspects of this model in a research titled as “Fractional programming: A tool for the assessment of sustainability”. As mentioned above, there are three main objectives for sustainable crop pattern, maximization of income and job opportunities and minimization of costs (In this case water consumption). Using fractional programming provides the possibility to make three goals in two goals which include maximization of “the net profit/water consumption” and “making job opportunity/water consumption”. In this way, the number of solutions is lower and therefore the decision-making process is easier. Fractional programming for planning and optimization cropping pattern has not been done yet. This paper is being studied to evaluate the stability in the agricultural systems of Bajestan plain located in the Razavi Khorasan province; and also determine the best cropping pattern. There are about 10,000 hectares of agricultural lands in the Bajestan plain. These lands are cultivated in seven major crops which include barley, saffron, wheat, pistachios, cotton, pomegranate and melon. Now the area under cultivation of these crops is 2250, 1630, 1500, 1400, 1200, 1350 and 670 hectares, respectively. In this region, about 70% of the working population are employed in agriculture.
To verify the effectiveness of the fractional models first of all, three mono goal linear models were prepared. The goal of each of these three models was maximization income and maximization of job opportunities and minimization of water consumption. By solving these models, three cropping patterns A1, B1 and C1 were obtained. For combination the triple dimensions of social, economic, and environmental, two relative criteria have been explained as the indications to evaluate system stability. Thus, in the next step, by dividing each of the two functions (maximization of income and maximization of job opportunities) to water consumption, two new objective functions were obtained in the form of fractional model. In fact, these two models represent two sustainability index. By solving those models, two cropping patterns A2 and B2 were obtained. Finally, an ideal fractional/mathematical programing model was prepared in which the last two functions were optimized. Optimization in relationships “the net profit/water consumption” and “making job opportunity/water consumption” leads to the new copping pattern (C2).
In optimized cropping pattern the area of barley, saffron, wheat, pistachios, cotton, pomegranate and melon obtained 111.4, 1608, 110.8, 7202.3, 103.1, 404.8 and 159.5 hectares, respectively. With the aim of maximizing the net profit, two relative criteria (“the net profit/water consumption” and “making job opportunity/water consumption”) in fractional model to the linear model increased 17.3% and 19.0%, respectively. With the aim of maximizing “making job opportunity”, two relative criteria in fractional model to the linear model increased 25.2% and 22.1%, respectively. In multi-goals programing approach, two relative criteria in fractional model to the linear model increased 32.4% and 42.5%, respectively. Overall, the ratio of income to water consumption in three cropping patterns of linear programming (A1, B1 and C1) was lower than three cropping patterns of fractional programming (A2, B2 and C2). The values are 17.8%, 26.7% and 33.3%, respectively. Also, the ratio of making job opportunity to water consumption in three cropping patterns of linear programming (A1, B1 and C1) was lower than three cropping patterns of fractional programming (A2, B2 and C2). The values are 18.9%, 22.1% and 42.5%, respectively. It can be concluded that fractional models in terms of both sustainability indices are superior to the linear models. These results are consistent with previous results and confirm them, such as Castrodeza et al. (2005), Maros et al. (2009), Hu et al. (2010) and Sabaghi et al.

کلیدواژه‌ها [English]

  • Job Opportunity-Optimization-Water Consumption.-Net Profit-