The Russian invasion of Ukraine is disrupting global agricultural commodity markets, creating pressure on wheat supplies and stocks and consequently on food prices. The wider effects are felt around the world due to the dependencies inherent to global trade. But how to assess the vulnerability of countries food security and how to deal with it? To assess for which countries food security is at risk, dependencies along with a set of coping capacity indicators to absorb shocks need to be identified. Addressing vulnerabilities at this scale requires a global food security approach, because the food security of vulnerable countries depends on measure taken by other countries, together with a holistic approach to water, energy and food security. The Russian invasion brings to the fore the need to reassess the socio-economic value of agriculture and open trade, in terms of food security for stability in vulnerable regions.

Major changes are occurring with far reaching implications for the existing equilibria or disequilibria in the water-energy-food-environment interface. The increased demand of energy worldwide will reflect directly and indirectly on water-dependent systems. Direct implications will come from higher energy prices, which make extraction and conveyance of water more costly. Indirect implications will be in the form of demand for alternative energy sources. It triggers demand for hydropower and remains a major driver—along with some environmental policies—for biofuel expansion. The key question is how these effects may alter water allocation and influence food security, rural poverty and environmental sustainability. This paper sets the background and context of this special issue by highlighting some of the major water-related policy issues related to the subject and provides an overview and synthesis of the papers in this special issue. Besides offering insight into how these papers address these questions in the practical context of few selected countries and basins, this paper also indicates some key areas for future research on the subject.

This paper provides insight into the relevance of market forces to typical problems found in irrigated agriculture. It first considers the theoretical basis for the use of economic instruments, such as volumetric water charges and tradable water rights, then considers their usefulness in the context of five case studies of irrigated areas, in Egypt, India, Indonesia, Morocco and Ukraine. The case studies confirm that competition for scarce water and shortage of funds are widespread. To assess the suitability of economic instruments to achieve water management objectives, insight is provided into the current price paid for irrigation water, the cost of service provision and the value to irrigators. It becomes clear that there is a big gap between the price and value of irrigation water. This means that a considerable increase in the price of water is needed to balance supply and demand, which would reduce farm economic welfare substantially. This socio-political problem, plus the technical and administrative complexity of measuring water, make water pricing an unsuitable approach to balance supply and demand.

Sustainable Development Goal indicator 6.4.1 is defined as the change in water use efficiency over time and measured as the change in the ratio of gross economic value added by irrigated agriculture, industry and the services sector to the volume of water withdrawn over time. The rationale behind this indicator is to decouple a country's economic growth from its water use. Yet, this unwittingly results in an economic distortion of the water balance, favouring increased water withdrawal in service of higher water-use efficiency, at the expense of environmental sustainability. This paper discusses three methodological flaws. First, aggregation of only economic values across all sectors ignores social and environmental values and is very sensitive to changes in the relative water use by agriculture versus industry and services. Second, the economic value derived from agriculture and from imports cannot in fact be decoupled from agricultural water use. Third, the indicator completely ignores the effects of diminished return flows to the environment due to increased re-use of water. A novel alternative, disaggregated WUE approach is therefore proposed, which links water consumption to the water balance. It is defined as the economic value of irrigated and rainfed agriculture combined with water consumption (ET_a) by rainfed and irrigated agriculture per area based on earth observation data. It is measured as the change in the ratio of gross economic value added by irrigated and rainfed agriculture to the volume of water consumed by rainfed and irrigated agriculture over time. This approach is more consistent and objective, while being methodologically, hydrologically and environmentally sound. It acknowledges the coupling of economic growth and water depletion, and the need to strike a balance between opportunities for economic growth and environmental sustainability. This better serves the full breadth of the water and sanitation goal as defined in SDG 6.

The increasingly urgent reform of water allocation is challenged by the complexity of the political dimension, in particular the need to reconcile often competing objectives such as food and energy security and green growth. Moreover, these objectives are unstable, and allocation regimes have to adjust to shifting priorities and circumstances at the lowest cost to society. Climate change generates additional uncertainty in water availability and demand. This calls for robust allocation regimes that can adjust, reallocate and reduce water allocation in an organized way.