Evaluating the Feasibility of Water Sharing as a Drought Risk Management Tool for Irrigated Agriculture

Droughts can exert significant pressure on regional water resources resulting in abstraction constraints for irrigated agriculture with consequences for productivity and revenue. While water trading can support more efficient water allocation, high transactional costs and delays in approvals often restrict its wider uptake among users. Collaborative water sharing is an alternative approach to formal water trading that has received much less regulatory and industry attention. This study assessed how the potential benefits of water sharing to reduce water resources risks in agriculture are affected by both drought severity and the spatial scale of water-sharing agreements. The research focused on an intensively farmed lowland catchment in Eastern England, a known hot-spot for irrigation intensity and recurrent abstraction pressures. The benefits of water sharing were modelled at four spatial scales: (i) individual licence (with no water sharing), (ii) tributary water sharing among small farmer groups (iii) sub-catchment and (iv) catchment scale. The benefits of water sharing were evaluated based on the modelled reductions in the probability of an irrigation deficit occurring (reducing drought risks) and reduced licensed ‘headroom’ (spare capacity redeployed for more equitable allocation). The potential benefits of water sharing were found to increase with scale, but its impact was limited at high levels of drought severity due to regulatory drought management controls. The broader implications for water sharing to mitigate drought impacts, the barriers to wider uptake and the environmental consequences are discussed.

A multi-objective water trading optimization model for Henan Province's water-receiving area in the Middle Route of China's South-to-North Water Diversion Project

Water trading is an effective method for solving regional water shortage problems and addressing the uneven spatiotemporal distribution of water resources. Therefore, taking the Middle Route of China's South-to-North Water Diversion Project (MR-SNWDP) as the research object, we present a study on a feasible water trading scheme in the water-receiving area of Henan Province. First, the tradable water of each calculation unit in the water-receiving area was calculated by analyzing the water-saving potential of different industries. Second, a multi-objective optimization model for trading water between different regions was developed, taking the largest social and economic benefits of the water-receiving area as the objective function. Finally, non-dominated sorting genetic algorithms were used to solve this optimization model, and an optimal scheme for water trading was proposed. The simulated results of the optimal scheme indicate that the total water shortage of the water-receiving areas will decrease by 650.69 million m3, and there will be a surplus of 14.98 million m3 of water, and the gross national product will increase by RMB 130.5 billion at a rate of 5.2%. This demonstrates that the water-receiving areas of Henan Province can effectively alleviate local water shortages by trading water without increasing external water supplies.