Comparative Trend Analysis of Suspended Sediment Concentration and Streamflow: A Multi-method Framework

Assessing short-term trends in Suspended Sediment Concentrations (SSC) and streamflow provides crucial insights for understanding water quality and sediment transport processes. This study aimed to investigate these trends in the Grand Canyon region, where such analyses remain limited. A robust statistical framework integrating Maximum Overlap Discrete Wavelet Transform (MODWT) and Mann-Kendall (MK) test was employed to examine trends at monthly, seasonal, and annual timescales across five monitoring stations during the 2008–2023 period. The Innovative Trend Analysis (ITA) and Bayesian Estimator of Abrupt changes, Seasonal cycles, and Trends (BEAST) were also applied to detect trends and identify change points. The MK test results indicated statistically significant decreasing trends in the SSC series at the monthly scale, with the 4-month component (D2) representing the dominant periodicity. For streamflow data, significant decreasing trends were observed at monthly and seasonal scales, with the 2-month component (D1) dominating monthly periodicities. At the annual scale, both SSC and streamflow exhibited insignificant decreasing trends. The ITA method detected additional underlying trends in the SSC series that were not identified by the MK test. Additionally, the BEAST method identified January 2012 as the most probable changepoint for streamflow series across all stations. This study provides key insights for water resource management, sediment budgeting, and water quality preservation in the Grand Canyon region.