Water-suitable reclamation can mitigate the amplified agricultural water stress driven by climate change in arid inland basin

Abstract

The escalation of water scarcity poses a significant challenge to the sustainability of irrigated agriculture in arid regions, with climate change further amplifying the unpredictability of water resources for agricultural purposes. Despite the critical nature of this issue, there is a lack of research identifying effective adaptation strategies and establishing water-suitable thresholds for agricultural development. This study modified a conventional approach for estimating irrigation water use (IWU) in the Heihe agricultural area of Northwest China, integrating the distributed hydrological components of the Soil and Water Assessment Tool (SWAT) model. It modeled IWU and surface water availability across three representative concentration pathways (RCPs) and conducted an extensive analysis of agricultural water scarcity for the period 2021–2050. The study established threshold levels for water-suitable agricultural development based on predicted local water resource conditions. Findings suggested a trend towards warmer and wetter conditions in the Heihe agricultural area over the next three decades. The anticipated average IWU, predicted by five general circulation models (GCMs), was expected to reach 26.785 × 108 m3 (RCP2.6), 26.827 × 108 m3 (RCP4.5), and 26.865 × 108 m3 (RCP8.5). These projections indicated an increase of 0.815 × 108 m3, 0.857 × 108 m3, and 0.895 × 108 m3, respectively, in comparison to the historical period spanning from 1985 to 2014. Streamflow was anticipated to diminish by 0.28 × 108 m3 (RCP2.6), 0.46 × 108 m3 (RCP4.5), and 0.23 × 108 m3 (RCP8.5). The predicted agricultural water scarcity index (WSI) was 1.764 (RCP2.6), 1.789 (RCP4.5), and 1.763 (RCP8.5), indicating a worsening of agricultural water use shortages due to climate change. The study identified controlling the scale of cultivation as the most effective adaptation strategy, recommending that water-suitable agricultural reclamation in the Heihe agricultural area be confined to 25 × 104 ha. This research offers a comprehensive assessment of future water security in an arid inland basin, providing valuable insights into the sustainable development of global irrigated agriculture and adaptation strategies in response to climate change.