Global proliferation of small hydropower plants

Freshwater researchers Thiago Couto and Dr. Julian Olden were recently published in Frontiers in Ecology and the Environment for their research about the proliferation of hydropower.


Increased societal demand for electricity has resulted in global proliferation of hydropower facilities, which harness and transform the energy of flowing water into a sustainable source of electricity.  However, increased public awareness about the socioeconomic costs of hydropower installations (e.g., greenhouse gas formation, decreased water quality and quantity, and decreased biodiversity) means that governments are moving away from construction of large hydropower installations and instead turning their attention to small hydropower plants.

Large hydropower dam
Hydropower installations are increasing in ubiquity around the world.

A recent study published by FWI researchers Thiago Couto and Dr. Julian Olden (SAFS) estimates that 82,891 small hydropower plants (SHPs) are currently operational in 150 countries around the world and that construction of SHPs is on the rise due to governmental incentives, private investments, and simplified licensing processes.  Considerably more ubiquitous than large hydropower plants, SHPs collectively contribute just 11% of global electricity generation capacity based on hydropower.  SHPs are presumed to produce smaller socioeconomic costs because of their smaller size, but a growing body of literature suggests that SHPs are also ecologically impactful.

Couto and Olden suggest that weak and inconsistent regulatory oversight, with little consideration for environmental impacts, has facilitated the rapid expansion of SHPs all over the world.  Management policies consider only the generation capacity of a SHP—how much power it can produce under optimal hydrologic conditions—and neglect other factors like mode of operation, the degree of river flow alteration, impacts on habitat connectivity, and the cumulative ecological effects of multiple SHP installations on a single river, which inform and control socioeconomic impacts of SHPs.

With an additional 10,569 SHPs slated for construction worldwide, Couto and Olden argue for stricter management policies informed by ecological evidence for the socioeconomic impacts of SHPs.  Until stronger regulations are implemented, it might be wise to reconsider the current pace of global SHP proliferation.

You can read their full study, published in Frontiers in Ecology and the Environment, here.

Additional media coverage of this publication can be found here.


Designing river flows to manage both food and energy demands

Freshwater Initiative faculty member Dr. Gordon Holtgrieve was recently published in Science for his work on the Mekong River in Southeast Asia.


A fisherman checks his nets on Tonle Sap Lake, Southeast Asia.

The Mekong River provides food for nearly 60 million people across 6 different countries. The 8th largest river in the world, the Mekong supports the largest lake and wetland in Southeast Asia, Tonle Sap Lake, which boasts an annual fishery harvest of roughly 250,000 tonnes. Dam construction along the Mekong and its tributaries may provide a clean energy source to this region of the world, but it also threatens freshwater fisheries critical for local livelihoods.

A new article published in Science and co-authored by SAFS professor and FWI member Dr. Gordon Holtgrieve offers a potential way to mitigate tradeoffs between hydropower development and fishery yields in the Lower Mekong Basin. Using 17 years of data, the researchers developed an algorithm to predict fishery yields from river flow and used it to design an ideal flow regime that would provide ample water for hydropower and also support the fishery. The result is a management strategy which may actually increase fishery yields in the Mekong River and other tropical rivers facing similar pressures worldwide.

Dr. Julian Olden, SAFS professor and FWI member, also co-authored a Perspective article on the integration of science, socioeconomics, and policy with regards to managing large rivers with dams, published in the same issue of Science. That commentary can be found here.

To read the UW News coverage of this article, click here.

To read the original research article, click here.


Riparian ecosystems threatened by changing flood and drought conditions

Freshwater Initiative faculty member Julian Olden was recently published in Nature Ecology & Evolution for his work on riparian ecosystems.


Human demand for freshwater has resulted in substantial alterations to the natural flow pattern of rivers all over the world. Dams and other water diversion infrastructure impact riparian ecosystems by decreasing flooding frequency and interrupting valuable ecosystem services such as habitat availability and nutrient cycling. Simultaneously, climate change threatens riparian ecosystems by increasing flow intermittency and drought frequency.

Riparian ecosystems like the one shown above are increasingly threatened by changing climate conditions.

A new study published last month in Nature Ecology & Evolution, co-authored by Dr. Julian Olden, Professor with the UW School of Aquatic and Fishery Sciences and part of the UW Freshwater Initiative, predicts how riparian ecosystems will respond to changing flood and drought conditions, the result of human-induced changes to water flow and climate change. Using population models and a holistic, network approach to thinking about rivers, the researchers found that increased drought conditions resulted in decreased connectivity, and thus decreased resilience, in interaction networks between plant guilds. Increased flow homogenization also decreased network connectivity, putting riparian communities at risk for biodiversity loss. Regular flooding is necessary to preserve the connectivity and resilience of dynamic river ecosystems into the future.

For the UW School of Aquatic and Fishery Sciences news announcement, click here.

To read the full research article, click here.