Presenter
Miss. Shiruo Hu, Tsinghua University
Co-author(s)
Prof. Jianshi Zhao, Tsinghua University
Dr. Jingrui Wang, Tsinghua University
Sub-theme
2. Promoting Water Efficiency, Productivity and Services
Topic
2-5. Water pricing and water rights reforms
Body
Agriculture accounts for 70% of all freshwater withdrawals globally, offering a lot of water-saving potentials. However, many studies found that increasing efficiency rarely reduces water consumption. This phenomenon is known as the paradox of irrigation efficiency. A limited understanding of the paradox of irrigation efficiency leads to the twin challenges of saving agricultural water and ensuring food security. In this study, we proposed a physics-based socio-agro-hydrological model and tried to take deeper insights into the paradox from the perspective of water pricing impacts on irrigation behavior. The coupled model was established by integrating (1) an agent-based model for farmers’ irrigation decisions under agricultural policies, and (2) a physics-based one-dimensional agro-hydrological model (i.e., LAWSTAC). The model was applied to Huinong experimental field, an arid irrigation district in northwestern China. Simulation scenarios were set to explore the influence of water prices on farmers’ irrigation behevior and agro-hydrological processes. The results showed that water prices increase reduces irrigation water use. Moreover, it helps to shift farmers’ irrigation decisions from individually optimal choices back to socially optimal ones. By this way, it could greatly save water and enhance irrigation efficiency without compromising crop yield and net profit. Besides, an effective adjustment range for water price regulation was identified to change the irrigation behavior of farmers, and the effectiveness of different types of agricultural subsidies were evaluated. Our study argues that the formation of the irrigation efficiency paradox could be attributed to two factors: insufficient efficiency growth and unrestricted expansion of irrigated land. Furthermore, this study suggests that adopting a policy of raising water prices, setting cultivated land restriction and providing subsidies on planting area can be an effective approach to achieving the dual goals of water-saving and ensuring food security and farmers’ income. These findings could advance our understanding of the irrigation efficiency paradox and highlight the necessity of considering farmers’ irrigation behavior and agro-hydrological processes in agricultural water policy development.