Coupled hydrogeomorphic and woody-seedling responses to controlled flood releases in a dryland river
Water Resources Research
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Abstract
Interactions among flow, geomorphic processes, and riparian vegetation can strongly influence both channel form and vegetation communities. To investigate such interactions, we took advantage of a series of dam-managed flood releases that were designed in part to maintain a native riparian woodland system on a sand-bed, dryland river, the Bill Williams River, Arizona, USA. Our resulting multiyear flow experiment examined differential mortality among native and nonnative riparian seedlings, associated flood hydraulics and geomorphic changes, and the temporal evolution of feedbacks among vegetation, channel form, and hydraulics. We found that floods produced geomorphic and vegetation responses that varied with distance downstream of a dam, with scour and associated seedling mortality closer to the dam and aggradation and burial-induced mortality in a downstream reach. We also observed significantly greater mortality among nonnative tamarisk (Tamarix) seedlings than among native willow (Salix gooddingii) seedlings, reflecting the greater first-year growth of willow relative to tamarisk. When vegetation was small early in our study period, the effects of vegetation on flood hydraulics and on mediating flood-induced channel change were minimal. Vegetation growth in subsequent years resulted in stronger feedbacks, such that vegetation's stabilizing effect on bars and its drag effect on flow progressively increased, muting the geomorphic effects of a larger flood release. These observations suggest that the effectiveness of floods in producing geomorphic and ecological changes varies not only as a function of flood magnitude and duration, but also of antecedent vegetation density and size.
Suggested Citation
Wilcox, A., Shafroth, P.B., 2013, Coupled hydrogeomorphic and woody-seedling responses to controlled flood releases in a dryland river: Water Resources Research, v. 49, no. 5, p. 2843-2860, https://doi.org/10.1002/wrcr.20256.
ISSN: 1944-7973 (online)
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Coupled hydrogeomorphic and woody-seedling responses to controlled flood releases in a dryland river |
| Series title | Water Resources Research |
| DOI | 10.1002/wrcr.20256 |
| Volume | 49 |
| Issue | 5 |
| Publication Date | May 28, 2013 |
| Year Published | 2013 |
| Language | English |
| Publisher | AGU |
| Contributing office(s) | Fort Collins Science Center |
| Description | 18 p. |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Water Resources Research |
| First page | 2843 |
| Last page | 2860 |
| Country | United States |
| State | Arizona |
| Other Geospatial | Bill Williams River |