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

中文翻译：

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密歇根州未扰动流域基础流量和BFI趋势分析—来自多目标优化的约束

记录地下水和地表水系统如何应对气候变化对于了解水资源至关重要，尤其是在美国大湖地区，那里观测到急剧的温度和降水变化。这项研究使用（1）多目标优化（MOO）和（2）修正的Mann–Kendall（MK）检验对短期自相关（STA）进行了校正，对密歇根州10个未受干扰的集水区进行了基流和基流指数（BFI）趋势分析。 。结果表明平均基础流量存在变化（0.09-8.70 m ³/ s）和BFI（67.9–89.7％），这会使区域范围的地下水补给外推复杂化。长期（> 60年）的MK趋势测试表明，基本流量和BFI对总降水量（P）和从雪到雨的过渡具有明显的控制作用。在下半岛步枪河流域，磷增加和从降雨到降雨的过渡增加了底流，其速度低于溪流。可能有助于记录洪水频率增加的总体模式。在上半岛福特河分水岭，磷的减少以及从降雨到降雪的过渡对基流和BFI没有显着影响。我们的结果强调了由于短期STA敏感性较低，客观约束的BFI参数对于短期（<50年）水文趋势分析的价值。