This study focuses on how the representation of daily precipitation probability distributions may affect the application of equidistant quantile matching (EDCDFm). Five representations, that is, two parametric distributions and three nonparametric approaches, are selected. The parametric distributions include Gamma and Weibull while the nonparametric approaches include empirical cumulative distribution function (ECDF) and kernel density estimation method (KDE) as well as an improved KDE named diffusion‐based kernel density estimation (DKDE). All five methods were applied to correct the daily precipitation of 11 stations over the Daqing River Basin, North China in 1981–2015. The results demonstrated that DKDE is closer to ECDF than the other three methods in the goodness‐of‐fit evaluation. Furthermore, nonparametric methods present advantages over parametric methods; especially, DKDE and ECDF are skilful equally and both of them display impressive comprehensive performance than other methods by multi‐index. These findings suggest that representing the precipitation probability distributions accurately is beneficial for the bias correction and selecting one or more suitable indexes is of great significance to the verification of EDCDFm. This study can provide guidance for future water resources management of the Daqing River Basin.

Closed-flume spatial constraints may bias swimming-performance data used in fish-passage design. Two independent experiments were conducted using different size classes of juvenile grass carp (Ctenopharyngodon idella). Fish with a mean body length (BL) of 7.92 ± 0.61 cm were used to assess five test-section lengths (8, 6, 4, 3.5, and 3 BL), whereas fish with a mean BL of 15.76 ± 0.97 cm were used to assess three blockage ratios (1.88%, 9.26%, and 15.31%). Incremental-velocity tests quantified critical swimming speed and behavior, and three-dimensional simulations examined the local flow field under the 9.26% blockage. Relative critical swimming speed was similar at 4–8 BL (9.71–9.95 BL/s) but decreased by 10.96% from 4 to 3.5 BL. Increasing blockage from 1.88% to 9.26% and 15.31% reduced it from 6.99 to 5.34 and 5.24 BL/s, respectively. Behavioral responses also depended on spatial constraint: shorter sections reduced the space available for forward movement and postural adjustment, whereas higher blockage restricted lateral body and tail movements. As velocity increased, fish intensified tail beating; under higher blockage, compensation relied increasingly on tail-beat frequency because amplitude adjustment was constrained, with greater variation among individuals. Simulations showed that local streamwise velocity near the maximum fish cross-section was 20.8–25.0% above inlet velocity. At least 4 BL is recommended for fish comparable to those in the length experiment. Below 5% is suggested as a precautionary blockage target.