Reconciling irrigated food production with environmental flows for Sustainable Development Goals implementation

Abstract

Safeguarding river ecosystems is a precondition for attaining the UN Sustainable Development Goals (SDGs) related to water and the environment, while rigid implementation of such policies may hamper achievement of food security. River ecosystems provide life-supporting functions that depend on maintaining environmental flow requirements (EFRs). Here we establish gridded process-based estimates of EFRs and their violation through human water withdrawals. Results indicate that 41% of current global irrigation water use (997 km3 per year) occurs at the expense of EFRs. If these volumes were to be reallocated to the ecosystems, half of globally irrigated cropland would face production losses of ≥10%, with losses of ∼20–30% of total country production especially in Central and South Asia. However, we explicitly show that improvement of irrigation practices can widely compensate for such losses on a sustainable basis. Integration with rainwater management can even achieve a 10% global net gain. Such management interventions are highlighted to act as a pivotal target in supporting the implementation of the ambitious and seemingly conflicting SDG agenda.

The Global Food‐Energy‐Water Nexus

“…Today, the main consumptive use of blue water (i.e., liquid water returned to the atmosphere as water vapor) is for irrigation (92%; Richter, ), which strongly increases green water flows at the expense of blue water flows. Irrigation is a major human disruption of the water cycle (e.g., Jägermeyr et al, ); indeed, many rivers are so strongly depleted that they no longer reach the ocean (e.g., the Colorado and the Rio Grande in North America), while lakes in basins with internal drainage (e.g., Lake Chad and the Aral Sea) are drying out (e.g., Richter, ). Irrigation can modify the local climate, possibly by increasing evapotranspiration and effectively cooling the near‐surface atmosphere (e.g., Mueller et al, , ; Sacks et al, ).…”

Capping Human Water Footprints in the World's River Basins

“…Concerns have been raised as to whether enough freshwater is available to complete the energy transition under the pathways currently pursued by the International Energy Agency, particularly water availability limiting bioenergy production (Holmatov et al, ; Mekonnen et al, ). Moreover, failure to restrain humanity's growing water footprint (WF) makes reaching the UN's Sustainable Development Goals (SDGs) a daunting task, not only dedicated SDG6 “to ensure availability and sustainable management of water and sanitation for all” but also other SDGs for which water is foundational (Colglazier, ; Jägermeyr et al, ).…”

“…limiting bioenergy production (Holmatov et al, 2019;. Moreover, failure to restrain humanity's growing water footprint (WF) makes reaching the UN's Sustainable Development Goals (SDGs) a daunting task, not only dedicated SDG6 "to ensure availability and sustainable management of water and sanitation for all" but also other SDGs for which water is foundational (Colglazier, 2015;Jägermeyr et al, 2017).…”

The Brisbane Declaration and Global Action Agenda on Environmental Flows (2018)

“…This UN framework presents a "bold and transformative agenda in support of the twin challenge: protection of Earth's life-support system while reducing hunger and poverty" (Jägermeyr et al, 2017). Water flows through and underpins all of the SDGs, notably but not only Goal 6 (Ensure access to water and sanitation for all), which includes targets to improve water quality by reducing pollution (6.3), and to protect and restore water-related ecosystems including rivers, wetlands, aquifers, and lakes (6.6, 15.1).…”