Spatiotemporal heterogeneity of artificial water replenishment in chinese crop rotation systems over two decades

Agricultural intensification boosts crop yields but compromises food security by straining scarce water resources. To address the lack of a quantitative understanding of how cropping systems and phenological processes influence artificial water replenishment (AWR), we combined remote sensing-derived vegetation, evapotranspiration, and precipitation data to construct a 1-km resolution dataset for major Chinese croplands from 2000 to 2019. Seasonal trend decomposition, spatial autocorrelation, and centroid analysis revealed three major findings. First, AWR varied substantially from 6.6 to 12.7 × 10 10 m³·year −1 and exhibited strong spatial clustering, with Moran’s I between 0.68 and 0.82. High-intensity zones were concentrated in the Huang-Huai-Hai Plain, where the AWR centroid remained throughout the study period. Second, cropping regimes and their transitions jointly shaped AWR, with co-occurring transition hotspots and high-AWR regions. Wheat-maize double cropping exhibited a mean AWR of 3.6 × 10 5 m 3 ·km - ², which was approximately fourfold higher than that of single-season rice, which averaged 0.9 × 10 5 m³·km - ². Cropping regimes were mostly maintained (80.58 %), while some cropping areas were converted to fallow (11.60 %) or other cropping systems (7.82 %). The near equal proportion between crop-to-fallow and fallow-to-crop conversions indicated intermittent and reversible fallowing rather than one-way withdrawal by cultivation. Third, AWR displayed a persistent seasonal cycle, peaking in July at values of up to 1.8 × 10 5 m 3 ·km - ². These results highlight the challenge of synchronizing agricultural water use with climate variability and underscore the urgent need to optimize cropping structures and irrigation strategies to achieve sustainable food production under increasing water stress. • AWR varied from 6.59 to 12.73 × 10 ¹ ⁰ m³ ·yr −1 , with hotspots in the Huang–Huai–Hai Plain and southern China. • AWR exhibits persistent spatial clustering with a stable centroid, indicating long-term hotspot persistence. • Summer AWR peaks reflect a seasonal mismatch between crop water requirement and monthly effective precipitation. • Cropping-pattern composition and intensity regulate regional AWR; and coincide with high-frequency transition zones.