Preliminary analysis of suspended sediment rating curves for the Kalamazoo River and its tributaries from Marshall to Kalamazoo, Michigan

Suspended sediment concentration (SSC) rating curves for the Kalamazoo River and its tributaries from Marshall to Kalamazoo, Michigan, U.S.A., were developed based on measured data. The slopes of the atsite SSC rating curves were of two general types: either increasing or decreasing with increasing discharges. By examining the basin characteristics and flow patterns, streams with negative SSC rating curve slopes were associated with groundwater-dominated streams and those with positive slope terms were associated with surface-water dominated streams. A panel regression with fixed-effects analysis was applied to the pooled atsite data according to various grouping criteria. The results from the subgroups which considered groundwater and surface-water dominance, seasonality, and dam effects showed better fit than the at-site SSC rating curves did. It was assumed that the rating curve slopes for sites in each subgroup were the same but their intercepts varied from site to site. The groundwater and surface-water dominance division was used as the basis for estimating SSC at ungaged sites. The study was conducted as a component of hydrodynamic modeling under the Enbridge Line 6B pipeline oil-spill recovery activities.