عنوان مقاله
کمبود آب و تاثیر بهبود مدیریت آبیاری
فهرست مطالب
مقدمه
کمبود آب و مزایای نسبی
مدل جدید GTAP-W
طراحی سناریوهای شبیه سازی
بحث و نتایج
نتیجه گیری
بخشی از مقاله
طراحی سناریوهای شبیه سازی
عملکرد و بهره وری کشاورزی آبی معمولاً کارایی آبیاری نامیده شده است. در فضا و زمان محدود، FAO (2001) کارایی آبیاری را به شکل نسبت آب آبیاری مصرف شده توسط محصولات به آب منحرف شده از منبع عرضه تعریف می کند.
هر گونه بهبود در کارایی آبیاری به بهبود در کارایی کلی آبیاری اشاره می کند. پروژه های جهانی عرضه و تقاضای آب نشان می دهد که تلاشهای انجام شده در راستای بهبود کارایی آبیاری عمدتاً در نواحی در حال توسعه کمبود آب به وقوع خواهد پیوست. چهار فاکتور براین مسئله تاثیرگذارمی باشد: رشد جمعیت، شهری شدن سریع، مصرف آب بالا در هر هکتار، و تغییر وضعیت اقلیمی.
کلمات کلیدی:
Agricultural Economics 42 (2011) 305–323 Water scarcity and the impact of improved irrigation management: a computable general equilibrium analysis Alvaro Calzadillaa,b,∗, Katrin Rehdanza,c , Richard S.J. Told,e,f aKiel Institute for the World Economy, Hindenburgufer 66, 24105 Kiel, Germany bInternational Max Planck Research School on Earth System Modelling, Bundesstrasse 55, 20146 Hamburg, Germany cChristian-Albrechts-University of Kiel, Department of Economics, Olshausenstraße 40, 24118 Kiel, Germany dEconomic and Social Research Institute, Whitaker Square Sir John Rogerson’s Quay, Dublin 2, Ireland eInstitute for Environmental Studies, Vrije Universiteit, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands f Department of Spatial Economics, Vrije Universiteit, De Boelelaan 1105, 1081 HV Amsterdam, The Netherlands Received 12 February 2009; received in revised form 3 February 2010; accepted 29 May 2010 Abstract Increasing water scarcity combined with an increasing demand for food and water for irrigation call for a careful revision of water use in agriculture. Currently, less than 60% of all the water used for irrigation is effectively used by crops. Based on the new version of the GTAP-W model we analyze the effect of potential water savings and the welfare implications of improvements in irrigation efficiency worldwide. The results show that a water policy directed to improve irrigation efficiency led to global and regional water savings, but it is not beneficial for all regions. The final effect on regional welfare will depend on the interaction of several different causes. For instance, higher irrigation efficiency changes opportunity costs and reverses comparative advantages, modifying regional trade patterns and welfare. For water-stressed regions the effects on welfare are mostly positive. For nonwater scarce regions the results are more mixed and mostly negative. The results show that exports of virtual water are not exclusive of water abundant regions. JEL classifications: D58, Q17, Q25 Keywords: Computable general equilibrium; Irrigation; Water policy; Water scarcity; Irrigation efficiency 1. Introduction Water is a scarce resource. Forty percent of the world’s population today face shortages regardless of whether they live in dry areas or in areas where rainfall is abundant (CA, 2007). The largest consumer of freshwater resources is the agricultural sector —globally around 70% of all freshwater withdrawals are used for food production. However, less than 60% of all the water used for irrigation is effectively consumed by crops. This article therefore analyzes the extent to which improvements in ∗Corresponding author. Tel.: 49-431-8814-401; fax: 49-431-8814-500. E-mail address: alvaro.calzadilla@ifw-kiel.de (A. Calzadilla). Data Appendix Available Online A data appendix to replicate main results is available in the online version of this article. Please note: Wiley-Blackwell, Inc. is not responsible for the content or functionality of any supporting information supplied by the author. Any queries (other than missing material) should be directed to the corresponding author for the article. irrigation management would be economically beneficial for the world as a whole as well as for individual countries and the amount of water savings that could be achieved. During the coming decades, water scarcity is expected to rise because of a rapid increase in the demand for water due to population growth, urbanization, and an increasing consumption of water per capita. By 2025, the world’s population is expected to rise from 6.5 billion today to 7.9 billion. More than 80% will live in developing countries and 58% in rapidly growing urban areas (Rosegrant et al., 2002). Consequently, 1.8 billion people are expected to live in countries or regions with absolute water scarcity, and two-thirds of the world population could be under stress conditions (UN-Water/FAO, 2007). In addition, climate change will influence the supply of water, modifying the regional distribution of freshwater resources (UN-Water/FAO, 2007). According to the United Nations (2006), during the last century, irrigation water use has increased twice as fast as population, allowing the global food system to respond to the
