Damming news: Geospatial media discourse analysis of dams.

Dams are a globally important social-ecological issue, and the practice of removing aging or obsolete dams is increasing in many countries where rivers have been used to fuel industrial growth. News media play an important role in providing information and raising awareness about dam-related decision making and patterns in news media coverage can shape public sense-making about potentially controversial dam decisions. This research focuses on spatial patterns of news media references to "dam removal" georeferenced to a New England dams database, the types of dam removal characteristics that contribute to newsworthiness, and specific media framing strategies. We develop a method, known as DAMMDA, that combines a large geodatabase of dam features and corpus of news media articles. We find that spatial patterns of "dam removal" news media coverage do not necessarily coincide with the actual occurrence of removed dams, nor the distribution of extant dams, in the landscape. Instead, a minority of dams with specific characteristics make up the majority of dam media references. Such "newsworthy dams" are capable of generating hydroelectricity, are situated on large rivers, are located in urban areas, or have already been removed. Further, references to newsworthy dams are often used to frame discussions about future dam decisions in other locations in New England and across the United States. We conclude by reflecting on how this approach is relevant for understanding complex and interconnected factors that can shape controversial sustainability issues, such as the relationships between news media and social-ecological characteristics of infrastructures within landscapes.

Managing dams for energy and fish tradeoffs: What does a win-win solution take?

Management activities to restore endangered fish species, such as dam removals, fishway installations, and periodic turbine shutdowns, usually decrease hydropower generation capacities at dams. Quantitative analysis of the tradeoffs between energy production and fish population recovery related to dam decision-making is still lacking. In this study, an integrated hydropower generation and age-structured fish population model was developed using a system dynamics modeling method to assess basin-scale energy-fish tradeoffs under eight dam management scenarios. This model ran across 150 years on a daily time step, applied to five hydroelectric dams located in the main stem of the Penobscot River, Maine. We used alewife (Alosa pseudoharengus) to be representative of the local diadromous fish populations to link projected hydropower production with theoretical influences on migratory fish populations on the model river system. Our results show that while the five dams can produce around 427 GWh/year of energy, without fishway installations they would contribute to a 90% reduction in the alewife spawner abundance. The effectiveness of fishway installations is largely influenced by the size of reopened habitat areas and the actual passage rate of the fishways. Homing to natal habitat has an insignificant effect on the growth of the simulated spawner abundance. Operating turbine shutdowns during alewives' peak downstream migration periods, in addition to other dam management strategies, can effectively increase the spawner abundance by 480-550% while also preserving 65% of the hydropower generation capacity. These data demonstrate that in a river system where active hydropower dams operate, a combination of dam management strategies at the basin scale can best balance the tradeoff between energy production and the potential for migratory fish population recovery.

A multiscale approach to balance trade-offs among dam infrastructure, river restoration, and cost.

Aging infrastructure and growing interests in river restoration have led to a substantial rise in dam removals in the United States. However, the decision to remove a dam involves many complex trade-offs. The benefits of dam removal for hazard reduction and ecological restoration are potentially offset by the loss of hydroelectricity production, water supply, and other important services. We use a multiobjective approach to examine a wide array of trade-offs and synergies involved with strategic dam removal at three spatial scales in New England. We find that increasing the scale of decision-making improves the efficiency of trade-offs among ecosystem services, river safety, and economic costs resulting from dam removal, but this may lead to heterogeneous and less equitable local-scale outcomes. Our model may help facilitate multilateral funding, policy, and stakeholder agreements by analyzing the trade-offs of coordinated dam decisions, including net benefit alternatives to dam removal, at scales that satisfy these agreements.