Geology topics

Francis J. Magilligan

Publications and source records attributed to Francis J. Magilligan.

3 recordsLinked to original sources

USGS2024

Incorporating climate change into restoration decisions: Perspectives from dam removal practitioners

Incorporating climate change into conservation and restoration decisions is increasingly important for natural resource managers and restoration practitioners to effectively address the underlying drivers of ecosystem change. Small dam removal is an example of a restoration tool that may offer multiple socioeconomic and ecological benefits in streams, including promoting climate resilience. With the pace of dam removals increasing, practitioners and researchers are well-poised to incorporate climate change into future dam removal decisions. Therefore, we surveyed dam removal practitioners across 14 states in the eastern United States to understand current practices of small dam removals, factors driving restoration decisions, and how climate change knowledge is incorporated into these decisions. We also aimed to identify barriers to and opportunities for knowledge exchange between practitioners and researchers. Of the 100 respondents, most (79%) consider climate change in their dam removal decisions to some extent. Despite this, many reported a lack of clear, relevant, and accessible data linking small dam removal to climate resilience benefits. Dam removal practitioners also indicated that they most often rely on climate change information garnered from conversations with colleagues, rather than from scientific research products. These results suggest that the co-production of relevant, salient research questions and readily accessible and interpretable research products (e.g., technical summaries, open access articles) may encourage practitioners to incorporate climate change science more consistently and efficiently into dam removal decisions. These findings may also translate to other stream restoration efforts to inform knowledge exchange and improve restoration outcomes in a changing climate.

Connecticut, Delaware, Kentucky, Maine, Maryland, ↗

USGS2017

Dam removal: Listening in

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 tends to quickly reestablish connectivity, restoring the movement of material and organisms between upstream and downstream river reaches; (4) geographic context, river history, and land use significantly influence river restoration trajectories and recovery potential because they control broader physical and ecological processes and conditions; and (5) quantitative modeling capability is improving, particularly for physical and broad-scale ecological effects, and gives managers information needed to understand and predict long-term effects of dam removal on riverine ecosystems. Although these studies collectively enhance our understanding of how riverine ecosystems respond to dam removal, knowledge gaps remain because most studies have been short (< 5 years) and do not adequately represent the diversity of dam types, watershed conditions, and dam-removal methods in the U.S.

Water Resources Research↗

USGS2017

Landscape context and the biophysical response of rivers to dam removal in the United States

Dams have been a fundamental part of the U.S. national agenda over the past two hundred years. Recently, however, dam removal has emerged as a strategy for addressing aging, obsolete infrastructure and more than 1,100 dams have been removed since the 1970s. However, only 130 of these removals had any ecological or geomorphic assessments, and fewer than half of those included before- and after-removal (BAR) studies. In addition, this growing, but limited collection of dam-removal studies is limited to distinct landscape settings. We conducted a meta-analysis to compare the landscape context of existing and removed dams and assessed the biophysical responses to dam removal for 63 BAR studies. The highest concentration of removed dams was in the Northeast and Upper Midwest, and most have been removed from 3 rd and 4 th order streams, in low-elevation (< 500 m) and low-slope (< 5%) watersheds that have small to moderate upstream watershed areas (10–1000 km 2 ) with a low risk of habitat degradation. Many of the BAR-studied removals also have these characteristics, suggesting that our understanding of responses to dam removals is based on a limited range of landscape settings, which limits predictive capacity in other environmental settings. Biophysical responses to dam removal varied by landscape cluster, indicating that landscape features are likely to affect biophysical responses to dam removal. However, biophysical data were not equally distributed across variables or clusters, making it difficult to determine which landscape features have the strongest effect on dam-removal response. To address the inconsistencies across dam-removal studies, we provide suggestions for prioritizing and standardizing data collection associated with dam removal activities.

PLoS ONE↗