Projecting irrigation water requirements across multiple socio-economic development futures - A global CGE assessment

The article explores the implications of income and population growth over crop output and the consequent changes in freshwater requirements for irrigation. We use three alternative patterns of global socio-economic development (SSP1, SSP2 and SSP5) in conjunction with expected technological change coming from inherent yield improvements. Compared to other projections of blue water uses in crop production, the research provides a new perspective by using a multi-regional macro-economic approach. Freshwater requirements are calculated using a global Computable General Equilibrium framework with the induced pressure over renewable freshwater resources measured through the Irrigation Withdrawals to Availability (IWA) indicator. The RESCU-Water model employed distinguishes between rainfed and irrigated crop production. The model database also introduces an improved accounting method to derive the value of irrigation freshwater as a separate factor of production. The results show a positive relationship between socio-economic development and irrigation water use in most areas. Water-challenged regions continue to increase the pressure they exert over their renewable freshwater resources. Higher growth scenarios (SSP1 and SSP5) exacerbate these trends, leading to a more pronounced expansion of global blue water withdrawals. The obtained growth in freshwater requirements hints at continued unsustainable withdrawals in many regions and provides further evidence to support the SDG target 6.4 referring to the need for improved water-use efficiency.