|
|
Abstract Dam removal is widely used as an approach for river restoration in the United States. The increase in dam removals--particularly large dams--and associated dam-removal studies over the last few decades motivated a working group at the USGS John Wesley Powell Center for Analysis and Synthesis to review and synthesize available studies of dam removals and their findings. Based on dam removals thus far, some general conclusions have emerged: (1) physical responses are typically fast, with the rate of sediment erosion largely dependent on sediment characteristics and dam-removal strategy; (2) ecological responses to dam removal differ among the affected upstream, downstream, and reservoir reaches; (3) dam removal...
|
We collected environmental DNA (eDNA) data from the Elwha River, home to the world’s largest dam removal project, to track the spatial and temporal patterns of species responses following dam removal. In total, we collected data for 11 different fish taxa, sampled at 25 sites ranging across 56 river kilometers in a wilderness river for 4 years following dam removal. We show that eDNA can effectively be used to determine whether fish have recolonized past former dams, and in some cases determine the spatial extent of that recolonization.
Categories: Data;
Tags: Aquatic Biology,
Charr,
Dam Removal,
Ecology,
Elwha River, All tags...
Elwha River,
Genetics,
Salmon,
USGS Science Data Catalog (SDC),
biota,
environmental DNA, Fewer tags
|
Understanding landscape responses to sediment supply changes constitutes a fundamental part of many problems in geomorphology, but opportunities to study such processes at field scales are rare. The phased removal of two large dams on the Elwha River, Washington, exposed 21 ± 3 million m 3, or ~ 30 million tonnes (t), of sediment that had been deposited in the two former reservoirs, allowing a comprehensive investigation of watershed and coastal responses to a substantial increase in sediment supply. Here we provide a source-to-sink sediment budget of this sediment release during the first two years of the project (September 2011-September 2013) and synthesize the geomorphic changes that occurred to downstream fluvial...
|
A substantial increase in fluvial sediment supply relative to transport capacity causes complex, large-magnitude changes in river and floodplain morphology downstream. Although sedimentary and geomorphic responses to sediment pulses are a fundamental part of landscape evolution, few opportunities exist to quantify those processes over field scales.We investigated the downstream effects of sediment released during the largest dam removal in history, on the Elwha River, Washington, USA, by measuring changes in riverbed elevation and topography, bed sediment grain size, and channel planform as two dams were removed in stages over two years. As 10.5 million t (7.1 million m3) of sediment was released from two former...
|
|
