Trend Analyses of Baseflow and BFI for Undisturbed Watersheds in Michigan—Constraints from Multi-Objective Optimization

Documenting how ground- and surface water systems respond to climate change is crucial understanding resources, particularly in the U.S. Great Lakes region, where drastic temperature precipitation changes are observed. This study presents baseflow index (BFI) trend analyses for 10 undisturbed watersheds Michigan using (1) multi-objective optimization (MOO) (2) modified Mann–Kendall (MK) tests corrected short-term autocorrelation (STA). Results indicate a variability mean (0.09–8.70 m3/s) BFI (67.9–89.7%) that complicates regional-scale extrapolations of groundwater recharge. Long-term (>60 years) MK significant control total (P) snow- rainfall transitions on BFI. In Lower Peninsula Rifle River watershed, increasing P transition from has increased at lower rate than streamflow; an overall pattern may contribute documented flood frequency increases. Upper Ford decreasing rain- snowfall had no effects Our results highlight value objectively constrained parameter shorter-term (<50 hydrologic analysis because STA susceptibility.