The changes in the time series of annual discharge of the tunnel, using MK and TFPW-MK tests, were presented in Table 3. The result indicated an upward trend in tunnel discharge with a slope of 0.2477. This trend was statistically significant at the 10% level in the (z=1.755, p=92.07) MK test, and the outcomes of the TFPW-MK Test with a z-statistic of 1.38 and a p-value of 83.39 confirmed there is a statistically significant upward trend in the discharge of the inter-basin water transfer tunnel to the Eskandari watershed over the study period.