Background The test of sediment transport variation points serves as the cornerstone for a thorough exploration of hydrological system evolution. Jialing River is the largest tributary in the upper reaches of the Yangtze River Basin, and its water and sediment changes exert a significant on the water and sediment dynamics in the mainstream. Hence, scrutinizing and analyzing sediment transport variation points in the Jialing River offers a scientific foundation for effective water resource management within the Yangtze River basin.

Methods Parameter test and non-parameter test were used for diagnosing variation points. Considering the distinct principles underlying the variation diagnosis methods of parameter and non-parameter tests, two diagnostic methods were selected in each category. The ordered clustering method and sliding t-test were selected for parametric tests, and the sliding run method and Pettitt method were selected for non-parametric tests, and the four methods were used to diagnose the variation points of the annual sediment transport at Beibei station in the Jialing River Basin from 1954 to 2021.

Results 1) Without considering the prior conditions of the two kinds of diagnostic methods, the year of variation obtained by parameter test was 1984, while the year of variation obtained by non-parameter test was 1985. Autocorrelation existed in the sediment transport sequence of Beibei station, after removing the sequence autocorrelation and carrying out the non-parametric test again its diagnostic results were consistent with the parametric test diagnostic results, and the diagnostic results of the four methods are all in 1984. 2) From 1954 to 1984, the variation amplitude of annual sediment transport was stable, and the overall decrease was after 1985, and the decrease amplitude of annual sediment transport was extremely significant. The annual average sediment transport from 1954 to 1984 was 145 x 10⁶ t, and from 1985 to 2021 was 42 x 10⁶ t, which decreased by 71.03% compared with before the mutation point. 3) The change of sediment sources was an important reason for the decrease of sediment transport at Beibei station. The direct reason for significant decrease of sediment transport was the alternating of abundant and dry years from 1970s to 1990s under the same runoff. Since the mid-1980s, the construction of water conservancy projects in the middle and upper reaches of Jialing River Basin has been increasing continuously, which was a significant driver of sediment transport reduction. Since the late 1980s, large-scale soil and water conservation measures have reduced the sediment transport modulus of Jialing River Basin, and the sediment transport reduction effect is significant.

Conclusions The variation point of annual sediment transport in Jialing River Basin from 1954 to 2021 occurres in 1984, and its variation is affected by the physical background changes such as sediment source, climate, water conservancy project construction and soil and water conservation measures.