S.Ahmad Hosseini - Faculty of Water & Soil, Tehran University, Karaj, Iran
Ali Bagheri - Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran.
A.Hossein Hoorfar - Faculty of Water & Soil, Tehran University, Karaj, Iran

Water has a crucial role in the process of sustainable development. However, in order to achieve more economic growth rates, particularly in developing countries, it is usually ignored. Although water is a limiting resource, the economic growth programms initiate reinforcing mechanisms which will lead to a growing demand for water. Being supported by socio-economic justifications, the programs enforce regional authorities to overexploit water resources. That process will result in deficiencies in the water recources yield capacities. But, what is worse is that the reinforcing mechanism will still be working as an unindented consequence of the economic growth programs. In the longterm, the carrying capacity of the resources in the area will diminish resulting in even economic losses. Such a phenomenon has been observed in Mashad palin in the north-eastern Iran. During the past 20 years a large number of agricultutral expansion programms have been carried out in the plain. Despite achieving higher rates of agricultural performance within the beginning years, the plain has experienced a 20 m fall in the level of groundwater table and consequently a diminish in the agricultural performance during the past 20 years, i.e. more water is now consumed to produce at the same level in the twenty five years ago. Analyzing the problem in a systemic way, the paper adopts an Eco-systemic sustainability (Eco-SS) paradigm which focuses on the dynamic mechanisms existing or initiating in a region, to study the system behavior. Acknowledging sustainable development and relying on the concept of viabilty loops, Eco-SS suggests to check reinforcing mechanisms to bring the system back into balance in accordance with sustainble development. The dynamic mechanisms in Mashad plain have been identified and analized in the paper, and, based on the concept of viability loops, sterategies will be suggested to make the development programms in the area sustainable.

Systems thinking, Sustainable devlopment, Sustainability, Viability loops Dynamic processes, Eco-systemic sustainability (Eco-SS), Mashhad plain, Iran