Comparative Drought-Resilience Index (DRI) of Low-Water-Use Alternative Forage Crops: Integrating Water-Use Efficiency, Forage Quality, and Carbon Sequestration

Abstract— Increasing drought frequency and severity in arid and semi-arid regions threatens forage availability and livestock system resilience. This study develops a novel Drought-Resilience Index (DRI) integrating eight criteria across four dimensions: water-use and productivity, drought resistance and stability, soil–water mechanisms, and forage quality with soil organic carbon (SOC) contributions. Opuntia ficus-indica (OFI), sorghum (Sorghum bicolor), and barley (Hordeum vulgare) were evaluated in two semi-arid sites with contrasting soil textures (calcareous loam, sandy) over three years under full and deficit irrigation (50% ETc). Criterion weights were determined using the Analytic Hierarchy Process (AHP) with input from ≥12 experts, while crop rankings were obtained via the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). HYDRUS-1D simulations and field measurements quantified changes in available water capacity (ΔAWC), soil evaporation reduction, and SOC fractions. Results show that integrating soil–water mechanism criteria significantly elevates OFI’s ranking, particularly in sandy soils where baseline water retention is low. OFI increased ΔAWC by +35 mm, reduced soil evaporation by >20%, and achieved TOPSIS closeness coefficients >0.75 across all scenarios, outperforming sorghum (0.68–0.71) and barley (≤0.66). Tornado sensitivity analysis revealed that ΔAWC and SOC jointly accounted for ~46% of OFI’s separation from the ideal solution. These findings indicate that perennial succulents like OFI function not only as drought-resilient forage crops but also as landscape-level adaptation tools, delivering co-benefits for carbon sequestration, land degradation neutrality, and nature-based climate solutions. Incorporating OFI into regional forage systems could simultaneously advance agricultural productivity and environmental restoration under intensifying climate stress.