Year: 2018

Nature Sustainability: Better trade-offs between hydropower production and dam sediment trapping – can this work and how?


Paradigms like “the right-project in the right place” have been proposed to make hydropower more sustainable by selecting low-impact / high-benefit dam sites. But what is a good strategy for selecting the right projects and places, and can such strategic hydropower planning really contribute to develop more sustainable hydropower? The February issue of Nature Sustainability “Strategic Planning for Dams” features the research of Rafael Schmitt and Matt Kondolf from UC Berkeley, together with Simone Bizzi and Andrea Castelletti from Politecnicno di Milano (“Improved trade-offs of hydropower and sand connectivity by strategic dam planning in the Mekong” DOI: 10.1038/s41893-018-0022-3). In that paper, we demonstrate that strategic selection of dam sites can greatly improve the trade-offs between hydropower production and dam sediment trapping, one of the key environmental impacts of dams.

The Se Kong, Se San, and Sre Pok form a major tributary basin of the lower Mekong and are a crucial source of sand for the lower Mekong and the Mekong Delta. This sand is of critical importance to build the floodplains of the lower Mekong and the coastline of the Mekong Delta. This sand supply would have been of even greater importance in the future, given that the Mekong Delta, which supports nearly 20 million people, is under substantial danger from rising sea levels and land subsidence (see, for example Schmitt et al. (2017) Losing ground – scenarios of land loss as consequence of shifting sediment budgets in the Mekong Delta
). However, there is also a great need for energy in the basin’s abuting countries. In the 3S basin, countries raced to develop hydropower dams without considering dam cumulative impacts and benefits, or a strategic analysis of which dam portfolios could achieve a given level of hydropower generation with minimal impact on the basin’s sand budget.

In our research, we found that the currently built dam portfolio will trap 90 % of the basin’s sediment load, while exploiting 50 % of the basin’s generation potential. By analysing nearly 17,000 alternative dam portfolios, we found that it would have been possible to generate the same amount of hydropower while trapping less than 20 % of the basin’s sand load. The current dam portfolio includes major dams on the river that carry most sand load. Our alternative portfolio consists of smaller dams in the upper parts of the basin and in rivers that carry naturally less sand.

We hope that our results will motivate additional efforts for building institutional frameworks to streamline strategic system-scale planning into the ongoing hydropower expansion world-wide and hence to find better trade-offs between energy needs and the delivery of fluvial ecosystem services. .

New Science Requirements in Support of a Modernized Columbia River Treaty

The Columbia River Treaty was an innovative agreement to coordinate management of the Columbia River to maximize benefits and equitably share them between the US and Canada.  It has been recognized as an excellent example of trans-boundary integrated water resources management, the concept that river basins be managed as integrated systems so that the total benefits are greater than would be the case if each country managed purely on its own narrow self interest, and then those benefits can be equitably shared.  When the Treaty was ratified in 1964, it did not adequately account for fisheries, river ecology, and the interests of tribes and first nations.  The impending treaty renewal has been widely seen as providing an opportunity to update the treaty by including consideration of these issues.  There are scientific uncertainties regarding impacts of dams and potential to restore fisheries on the river and its tributaries, the benefits of flood storage in Canadian dams, etc, which merit attention.  And looming over all treaty-related deliberations now is the recent change in US administrations, introducing uncertainty about whether the US will respect the cooperative nature of the last five decades of trans-boundary management of the Columbia River and approach updating of the agreement in a collaborative manner.

A group of scientists supported by representatives of First Nations and Tribes from Canada and the United States held a workshop at the Centre for Canadian Studies and Institute of International Studies at the University of California, Berkeley in April 2017 to develop recommendations for effectively integrating science into the treaty renewal process.

Changing Channels Workshop

A review and discussion of the science of stream restoration in the Russian River Watershed

January 26, 2018, 8:30 am-5 pm

Cloverdale Citrus Fairgrounds Auditorium, 1 Citrus Fair Drive, Cloverdale, CA


The geomorphic and watershed processes creating entrenched channels; limitations to riparian and aquatic habitat in entrenched channels; influences of historical developments on present day creek form and function; examples of restoration techniques that address entrenchment; and a discussion of the effects of recent fires on creeks.

Featured Speakers

Dr. Matt Kondolf & Dr. Doug Shields, Russian River Independent Science Review Panel

Drs. Lorraine & Alan Flint, Climate Scientists, USGS

Dr. Brian Cluer, NOAA


Workshop Flyer and Agenda

New Publication on Mekong Delta, free access until 15 February

A team of active researchers in the Mekong have published a paper, Changing sediment budget of the Mekong: Cumulative threats and management strategies for a large river basin, available for free downloads until 15 February.

Two decades after the construction of the first major dam, the Mekong basin and its six riparian countries have seen rapid economic growth and development of the river system. Hydropower dams, aggregate mines, flood-control dykes, and groundwater-irrigated agriculture have all provided short-term economic benefits throughout the basin. However, it is becoming evident that anthropic changes are significantly affecting the natural functioning of the river and its floodplains. We now ask if these changes are risking major adverse impacts for the 70 million people living in the Mekong Basin. Many livelihoods in the basin depend on ecosystem services that will be strongly impacted by alterations of the sediment transport processes that drive river and delta morpho-dynamics, which underpin a sustainable future for the Mekong basin and Delta.

Drawing upon ongoing and recently published research, we provide an overview of key drivers of change (hydropower development, sand mining, dyking and water infrastructures, climate change, and accelerated subsidence from pumping) for the Mekong’s sediment budget, and their likely individual and cumulative impacts on the river system. Our results quantify the degree to which the Mekong delta, which receives the impacts from the entire connected river basin, is increasingly vulnerable in the face of declining sediment loads, rising seas and subsiding land. Without concerted action, it is likely that nearly half of the Delta’s land surface will be below sea level by 2100, with the remaining areas impacted by salinization and frequent flooding. The threat to the Delta can be understood only in the context of processes in the entire river basin. The Mekong River case can serve to raise awareness of how the connected functions of river systems in general depend on undisturbed sediment transport, thereby informing planning for other large river basins currently embarking on rapid economic development.

Human-River Interactions in Cities

ISRivers Conference Session

With the explosion of urban waterfront revitalization projects in the developed world, it is timely to reflect on the relations between cities and their rivers: how the rivers influenced development of the cities, how cities have treated their riverfronts over time, and how the spatial relations of city and river constrain and enable improved connectivity between urban populations and their rivers.  This topic will be explored in a session in the upcoming conference ISRivers in Lyon, France, 4-8 June 2018.  IS Rivers, held every three years, is an interesting mix of researchers and practioners, from Europe and beyond.  The setting in Lyon is particularly good for our topic, as the ‘reconquest’ of the banks of the Rhone is a compelling story of returning river banks to ‘the people’ (in this case, from their former use as parking lots).

Human-River Interactions in Cities: Special Issue in Sustainabilty

Editors: G. Mathias Kondolf, Amir Gohar, and Yves-François LeLay

Most cities are located on rivers, and for very good historical reasons that included navigation/commerce, fisheries, water supply, waste disposal, and quotidian uses such as washing clothes. The identities and distinctive characteristics of many cities are closely tied to their rivers, and the many ways their residents interact with their urban waters. In recent decades, urban riverfront projects have become ubiquitous in the developed world, and increasingly promoted in the developing world. Both celebrated as revitalizing neglected urban centers and criticized for displacing the disenfranchised populations, these projects raise questions about what constitutes ‘restoration’ in the urban context, to what degree natural processes and ecological values can be restored in such contexts, and how sustainable ecological benefits will be in light of the urban context. In highly dense cities, the social benefits of restoration likely overshadow the potential ecological benefits. Moreover, attempts to transplant waterfront restoration approaches from a successful application in one city to another with different characteristics commonly fail when the diversity of fluvial process, form, and culture is not adequately accounted for. We invite your contributions to this special issue exploring these rich human-river interactions in the urban environment.