Soil moisture plays a crucial role in determining the yield of winter wheat. The Huang-Huai-Hai (HHH) Plain is the main growing area of winter wheat in China, and frequent occurrence of drought seriously restricts regional agricultural development. Hence, a daily-scale Non-stationary Standardized Precipitation Evapotranspiration Index (NSPEI), based on winter wheat crop coefficient (Kc), was developed in the present study to evaluate the impact of drought characteristics on winter wheat in different growth stages. Results showed that the water demand for winter wheat decreased with the increase in latitude, and the water shortage was affected by effective precipitation, showing a decreasing trend from the middle to both sides in the HHH Plain. Water demand and water shortage showed an increasing trend at the jointing stage and heading stage, while other growth stages showed a decreasing trend. The spatial distributions of drought duration and intensity were consistent, which were higher in the northern region than in the southern region. Moreover, the water shortage and drought intensity at the jointing stage and heading stage showed an increasing trend. The drought had the greatest impact on winter wheat yield at the tillering stage, jointing stage, and heading stage, and the proportions of drought risk vulnerability in these three stages accounted for 0.25, 0.21, and 0.19, respectively. The high-value areas of winter wheat loss due to drought were mainly distributed in the northeast and south-central regions.

The hydrological cycle across the source regions of the Yellow River (SRYR) affects water supply for 324 million people across the Yellow River basin (YRB), and the scarcity of meteorological stations leads to great challenges for the estimation of hydrologic and energy balance. Therefore, our work employs multisource precipitation products across the YRB to develop a new integrated precipitation product with the optimized Bayesian mean algorithm (OBMA). It investigates the performance and hydrological utility of the optimal Bayesian integrated precipitation product (OBIPP). This study found that the OBIPP improved by 14.08% in overall performance relative to the optimal precipitation product across the SRYR, respectively. Meanwhile, the variable infiltration capacity (VIC) model, driven by daily OBIPP, can drastically improve the accuracy of runoff simulation compared with other precipitation products across the SRYR. According to the VIC model driven by daily OBIPP, the average precipitation and runoff depth across the SRYR were approximately 621 mm and 64 mm from 2001 to 2019, respectively, showing a spatial trend increasing from northwest to southeast. Overall, OBIPP is characterized by smaller uncertainty of simulation and higher simulation performance across the SRYR, which should provide a scientific basis for accurate prediction and assessment of water resources in areas where meteorological data are scarce.