Weak and Strong Sustainability of Irrigation: A Framework for Irrigation Practices Under Limited Water Availability

Abstract

Agriculture strongly relies on irrigation. While irrigated land accounts for roughly 20% of the global cultivated area, it contributes to about 40% of crop production. In the last few decades, the growing demand for agricultural commodities has translated into an increasing pressure on the global freshwater resources, often leading to their unsustainable use. Here we investigate the sustainability of irrigation, balancing farmers' profit generation objectives and the needs of ecological systems. We ask the question "sustainability of what?" to stress how the sustainability of irrigation is often evaluated with respect the opposing needs of humans and nature. While from the farmers' perspective irrigation is sustainable when it provides uninterrupted access to water resources at a price not exceeding the marginal revenue they generate (clearly without accounting for environmental externalities), from the standpoint of water resources, irrigation is sustainable if it does not deplete freshwater stocks or environmental flows. We invoke the notions of "weak" and "strong" sustainability to develop a novel framework for the evaluation of tradeoffs between human needs and the conservation of natural capital. Through the analysis of criteria of performance, we relate water deficit and irrigation overuse to the reliability and resilience of irrigation. This approach is applied to the case of Australia, a major agricultural country affected by water scarcity. The application of the framework to the case of Australia shows how this approach can be used to highlight areas in which irrigation contributes to a weakly sustainable use of water resources with impacts on environmental flows and groundwater stocks. Solutions, such as increasing efficiencies or reducing water applications through the adoption of deficit irrigation, can enhance water sustainability in some water scarce locations.

The global value of water in agriculture

“…6 B ), these water provision costs are overall negligible with respect to the average value of water in agriculture in Australia, which is here estimated at ∼$0.27/m 3 ( Fig. 4 ), in agreement with estimates ($0.17 to $0.40/m 3 ; SI Appendix , Table S3 ) based on irrigation and production data from the Australian Bureau of Statistics ( 48 ). As noted below, these values fall within the interval of water prices reported by the Murray–Darling water market, suggesting that in the case of Australia the assumption of negligible provision costs can be overall justified.…”

“…However, in Australia, the Bureau of Statistics reports the total cost of irrigation by region, including the costs of equipment, infrastructure, water license, and operation, in addition to data on irrigated areas and agricultural water withdrawals ( 47 ). A recent analysis of these data ( 48 ) has provided annual water provision costs per unit area of irrigated land. We can use these results to estimate the annual cost of water provision per unit volume of irrigation water and compare them to our estimates of the value of water.…”

Drought in Northeast Brazil: A review of agricultural and policy adaptation options for food security

“…Irrigation is the most effective practice to combat water shortage in agriculture. Over 40% of global food production is sustained by less than 20% of cropland areas that maintain high levels of yields through irrigation systems (Borsato et al, 2020;FAO, 2019). On the other hand, irrigation accounts for about 70% of global freshwater use (Rockström et al, 2017), requiring large amounts of freshwater transposed, stored, or extracted from ground reservoirs, potentially resulting in severe landscape and environmental impacts (Khan et al, 2006).…”

“…Although predicting all possible impacts of such large and controversial project remains a challenge, integrated data and modeling analysis studies can aid decision-making, helping prioritize actions to mitigate potential impacts (Borsato et al, 2020;Krol & Bronstert, 2007;Roman, 2017). Although the transposition of Sao Francisco River is not completed, most of the irrigated agriculture in NEB is concentrated in developed regions along the Sao Francisco River.…”

Carnivores cross irrigation canals more often through overpasses than through culverts

“…As rainfall becomes scarcer or more erratic in many areas worldwide (Cisneros et al, 2014;Chemnitz et al, 2019), we rely increasingly on irrigation systems for agricultural and human water provision. Over 24 % of global land is facing severe water scarcity and 35 % of the population lives with water shortages (Borsato et al, 2020). Although only 20 % of cultivated areas are irrigated, this is where 40 % of the world's food is produced (Rossi, 2019).…”