Patterns of Floodplain Spatial Heterogeneity in the Southern Rockies, USA

Wohl, Ellen; Iskin, Emily

ABSTRACT: Floodplain spatial heterogeneity describes the three‐dimensional patchiness of floodplain substrate, surface elevation, and land cover. This heterogeneity results primarily from lateral channel migration and avulsion and decreases under diverse forms of management. Heterogeneity influences floodplain storage time, resilience to disturbance, and biodiversity. We use a data set of 37 floodplain segments covering a range of drainage areas and channel geometries from sites in the Southern Rocky Mountains to examine correlations between floodplain spatial heterogeneity and lateral valley confinement, drainage area, channel planform, and river management. We hypothesized that heterogeneity correlates most strongly with channel planform but found that the best explanatory statistical model included drainage area, planform, and gradient. Pairwise comparisons of means indicate that straight channels have the least heterogeneous floodplains and meandering channels have the greatest, while braided and anastomosing channels have intermediate values. Pairwise comparison of managed and unmanaged river corridors indicates that these populations are significantly different.