The original XAJ and improved XAJ models were used in the Shibantang watershed to simulate daily discharge series. The optimized parameters of the original XAJ model and improved XAJ model are listed in Table 2, and the simulation results of these two models are given in Figure 6(a), accompanied by observations. Five performance metrics were used to evaluate the simulation results for each year, including NSE, KGE, FPRE, FVRE, and RMSE (see Section 3.4 for more information). Table 3 illustrates the original and improved model's performance during the calibration and validation period, and Figure 6(b) and 6(c) displays the annual performance metrics of these two models.