Abstract:

Drought is one of the major meteorological disasters affecting winter wheat production in the Huang−Huai−Hai region. Water deficits during winter wheat growing season directly affect the final yield and grain quality. Based on meteorological data from 39 high−standard farmland stations, soil relative moisture data and historical climatic data from national meteorological stations in Henan province during 2020−2023, this study established daily−scale Standardized Precipitation Evapotranspiration Index (SPEI) and Crop Water Stress Index (CWSI) to evaluate their applicability in drought monitoring for high−standard farmlands. The results showed that: (1) for 84.6% of stations showed extremely significant (P＜0.01) positive correlations between SPEI and soil relative moisture index (Rsm), with correlation coefficients ranging from 0.15 to 0.73. Although SPEI overestimated regional drought severity compared to Rsm, it showed high consistency with actual disaster during the severe drought year 2022, when the grades difference was −0.60. (2) For 69.2% of stations exhibited extremely significant (P＜0.01) negative correlations between CWSI and Rsm, and the correlation coefficients were −0.47 to −0.11, with notable spatial variation. The percentage of days with a drought grades error ≤1 compared to Rsm at the station level was 70.0%, but there was a lagged response to the start and end of drought events. (3) SPEI and CWSI demonstrated good applicability for drought monitoring at regional and station level, respectively. It is recommended to optimize the baseline parameters of CWSI before wide application, and to establish a high−standard farmland drought monitoring system, which should integrate SPEI as an early−warning indicator for regional meteorological drought and CWSI as an decision−making tool for irrigation management at the station level.

Key words: Standardized precipitation evapotranspiration index, Crop water stress index, Soil relative moisture, Drought index, High?standard farmland