Unintended consequence of managing the coupled humans and water: the irrigation efficiency paradox

Abstract:

Water shortage most severely restricts the socio-economic development of many arid and semi-arid regions in the world, for which water-saving technology is believed to be an effective solution. However, as a realworld case, the total water consumption of Xinjiang Uygur Autonomous Region of China continued to increase as irrigation efficiency dramatically improved through the application of water-saving technology in the study period 1998–2010. This phenomenon, known as the irrigation efficiency paradox or Jevons paradox, is interpreted as an economic rebound effect. In this study, we explore the dynamic feedbacks between humans and water in this paradox through a socio-hydrological perspective. We analyze the co-evolutionary trajectory of coupled human–water dynamics from 1950 to 2010 to provide it a general context. A conceptual socio-hydrological model based on five key elements, namely, irrigation land, water-saving technology, water consumption, societal sensitivity to water scarcity, and the policy mix, is constructed. The policy mix to be adopted is determined by a social decision-making process mainly based on the societal sensitivity, which reflects the societal preference on two sorts of policies: (i) irrigation land control and (ii) water-saving technology promotion. Modeling results verify the hypothesized mechanism by successfully reproducing the observed dynamics including the emergence of the efficiency paradox. Our analysis indicates that the implementation of more adaptive rules may even eliminate the paradox. The effects of different initial policy mixes are also explored, and the results show that land control policies should be given equal priority when dealing with water scarcity. These findings point to a double-helix-type co-evolution of humans and water.