Aims: Studying flood peak discharge trends is crucial to disaster risk reduction in developing countries like Iran. This study aims to analyze the instantaneous peak discharge trend in 301 hydrometric gauge stations using Mann Kendal (MK (and Sen’s Slope estimator tests over Iran.
Material & Methods: Data on all existing hydrometric gauge stations in Iran were downloaded from Iran Water Resources Management Company. The hydrometric gauge stations with at least 20 years of data were selected, and the stations that were then affected by the dams were removed. trend analyses of instantaneous peak discharge were conducted using MK and Sen’s slope estimator tests.
Findings: The results showed that out of 301 hydrometric stations, 259 stations have no trend, only three stations have a decreasing trend, and 39 stations have an increasing trend. This trend is more evident in southwestern Iran, where the increase in agriculture, human activity, and climate change is more evident. In the watershed of the eastern border, only one station has a decreasing trend; in the central plateau, four stations have a decreasing trend, and the rest have no trend.
Conclusion: Due to the importance of peak discharge in flood damage, this research can help managers and decision-makers in integrated watershed management. For example, in flood control projects, as well as designing the dimensions of structures such as retard dams, levees, the height of flood control walls, and bridges.