Author: riverlab


River restoration projects in North America that involve reconfiguration of stream channels are dominated by symmetrical, single-thread meandering channels.  Although the meander dimensions are commonly justified by relations between channel width and meander wavelength, the universal preference for single-thread meandering channels in restoration projects is rarely questioned.  The aesthetic appeal of s-shaped curves in art and landscape design may help explain the prevalence of this form in river restoration projects. Riverlab alumna Kristen Wilson (Nature Conservancy) gave 300 freshwater scientists attending her keynote talk 5 minutes to draw a restored stream.  She compiled the results to see what mental images these scientists had for restored channels. Most depicted single-thread meanders for their restored channel, although there were interesting variants.  See Kristen’s just-published paper here.


Figure 1. The ideal meander with its repeating, regular, and symmetrical bends as drawn by select respondents, isolated to the channel pattern, and overlaid to emphasize the similarity in the form. A.—One wavelength. B.—1.5 wavelength. C.—Two or more wavelengths drawings.

Throughout the humid tropics, increased land disturbance and concomitant road construction increases erosion and sediment delivery to rivers.  Building road networks in developing countries is commonly a priority for international development funding based on anticipated socio-economic benefits. Yet the resulting erosion from roads, which recent studies have shown result in at least ten-fold increases in erosion rates, is not fully accounted for.  While effects of road-derived sediment on aquatic ecosystems have been documented in temperate climates, little has been es with rapidly eroding sites, completely new deltas of freshly deposited sediment were formed, prograding into the river channel. 

Riverlab alumni Blanca Rios and Scott Walls joined with Matt Kondolf to study periphyton biomass and macroinvertebrate communities on the deltas of Río San Juan tributaries, comparing north-bank tributaries draining undisturbed rain forest with south-bank tributaries receiving runoff from the partially-built road experiencing rapid erosion. Periphyton biomass, richness and abundance of macroinvertebrates overall, and richness and abundance of Ephemeroptera, Plecoptera and Trichoptera were higher on the north-bank tributary deltas than the south-bank tributary deltas. These findings were consistent with prior studies in temperate climates showing detrimental effects of road-derived fine sediment on aquatic organisms.  A Non-Metric Multidimensional Scaling (NMDS) analysis showed the impacted community on the south-bank deltas was influenced by poorly-sorted substrate with greater proportions of fine sediment and higher water temperatures.  The paper is freely available (open-access) here.

Rios-Touma, B, GM Kondolf, and SP Walls. 2020. Impacts of sediment derived from erosion of partially-constructed road on aquatic organisms in a tropical river: the Río San Juan, Nicaragua and Costa Rica. PLoSONE 15(11):e0242356.

Figure 1. Reach of Rio San Juan from approximately River Km 83.3 to 84.3 (downstream of the outlet of Lake Nicaragua)
Figure 2. Macroinvertebrate richness of south-bank versus north-bank tributary deltas of the Rio San Juan, MarchMay 2014.

With great regret, we cancel the 2020 shortcourse at Sagehen Creek Field Station, due to the many complications arising from the CVID-19 pandemic and the challenges in avoiding problems in holding the shortcourse at the station.  Those already registered are entitled to a full refund or may defer their participation to next year’s course offering, 16-20 August 2021.   We apologize for this very disappointing news, but look forward to better conditions under which we can once again hold the course next year.  We thank you for your understanding.


Matt Kondolf and the Sagehen Teaching Team

Geomorphic and Ecological Fundamentals for River and Stream Restoration

EPA Watershed Management Postgraduate Research Opportunity
DEADLINE: May 29, 2020
Office of Water | Washington, DC | Full-time | MONTHLY STIPEND PROVIDED

This opportunity will provide excellent exposure to the interface of watershed technical issues and environmental policy. It also offers exposure to the interaction between State and EPA CWA program practitioners in implementing their respective responsibilities under the CWA 303(d) program. Under the guidance of a mentor, the research participant will be involved in the activities above and will learn: (1)The respective roles of EPA, states and tribes in achieving the goals of the Clean Water Act (CWA) to achieve and maintain water quality; (2) Programmatic approaches and policy and technical tools to identify and develop restoration and protection plans for impaired or high quality waters, including those related to address nutrient impairments; (3) How states and EPA can continue to push the CWA 303(d) listing and TMDL program to better achieve environmental results in ways tailored to specific state priorities; (4) How to leverage different media to convey water quality information to a variety of audiences.

>>Job description


You may be interested in a new analysis of the effects of recently completed Xayaboury Dam (on the Mekong mainstem near Luang Prabang) and a cascade of dams upstream in China on flow patterns in the Lower Mekong River. The paper, Mekong River, Xayaboury Dam, and Mekong Delta in the first half dry season 2019-2020 by Nguyen Ngoc Tran was published in Vietnamese in TIA SANG, a scientific journal published by the Ministry of Science and Technology. The English version is now available here. As illustrated in excerpts of Figures 5 and 6 from the paper, the hydrologic analysis shows that flows this dry season have been significantly lower than in prior years’ dry seasons.

Riverlab members have contributed scientific papers on the cumulative effects of upstream dams on the sediment budget of the Mekong Delta and other threats to the sustainability of the Delta (Kondolf et al 2014, Kondolf et al 2018) and the potential for strategic dam planning to minimize impacts of dams on downstream sediment budgets and fish migration (Schmitt et al 2019).

Water levels in the Mekong River at Nakhon Phanom reflecting severe drought conditions in the current dry season of the 2019-2020 water year. (Source: Nguyen Ngoc Tran. 2020, Mekong River, Xayaboury Dam, and Mekong Delta in the first half dry season 2019-2020, Figure 5.)

View of the exposed bed of the Mekong River at Nakhon Phanom in late October 2019, reflecting severe drought conditions in this year’s dry season. (Source: Nguyen Ngoc Tran. 2020, Mekong River, Xayaboury Dam, and Mekong Delta in the first half dry season 2019-2020, Figure 6.)

References Cited

Kondolf, G.M., Z.K. Rubin, J.T. Minear. 2014. Dams on the Mekong: Cumulative sediment starvation.  Water Resources Research 50, doi:10.1002/2013WR014651. >>link to paper

Kondolf, GM, RJP Schmitt, P Carling, S Darby, M Arias, S Bizzi, A Castelletti, T Cochrane, S Gibson, M Kummu, C Oeurng, Z Rubin, and T Wild. 2018. Changing sediment budget of the Mekong: Cumulative threats and management strategies for a large river basin. Science of the Total Environment 625: 114-134. >>link to paper

Schmitt, R, S Bizzi, AF Castelletti, J Opperman, GM Kondolf. 2019. Planning dam portfolios for low sediment trapping shows limits on sustainable hydropower in the Mekong. Science Advances 5: eaaw2175 >>link to paper


The government of Cambodia announced on 16 March that it would postpone development of any of new dams on the mainstem Mekong River for 10 years, citing the need to develop alternative sources of energy for the country’s future development. While Cambodia has built a large dam on the SeSan-SrePok (important downstream tributaries), and left open the possibility it might build other tributary dams, the mainstem dams long-planned for Sambor and Stung Trang are on hold for the next decade. See story in the Guardian here.

Environmental Scientist: Regulatory Compliance Specialist – Pacific Watershed Associates

Pacific Watershed Associates is seeking applicants for the position of Environmental Scientist: Regulatory Compliance Specialist based in their office in McKinleyville, Humboldt County, California. Pacific Watershed Associates Inc., established in 1989, is a full service geological, hydrological, engineering, and biological consulting firm specializing in the development of technically sound management, restoration, and environmental solutions for watershed, forest, riverine, and coastal habitats. PWA is based in McKinleyville, California with an office in Petaluma (northern San Francisco Bay Area).

The application deadline is March 17. Click on the link bellow to view the job posting.

River Restoration: Fluvial-Geomorphic and Ecological Tools

22-26 June 2020, Beaumont du Ventoux, Provence FR

This shortcourse/workshop emphasizes understanding geomorphic process as a sound basis for planning and designing river restoration projects and programs, with specific applications and field visits to Mediterranean and mountain environments. The course draws heavily on innovative process based river restoration and management experiences in France and elsewhere in the EU, complemented by experiences in North America. Instruction includes lectures, field exercises, problem sets and workshops on approaches to planning and implementing process-based restoration, with instructors drawn from both sides of the Atlantic.

Adaptive Management for an International River Basin: The Future of the Columbia River Treaty

The Columbia River Treaty between the US and Canada has been recognized as an innovative example of the bi-national management of the water resources of an international river. However, when the Treaty was ratified in 1964, it did not adequately consider the rights and responsibilities of tribes and First Nations or local residents, ecological functions such as fish and fish habitat, instream flow needs, river processes and ecology, etc. Additionally, the treaty did not address issues such as water requirements for municipal, industrial and agricultural uses, river transport and recreation, water quality, or potential changes in runoff characteristics and water temperature as a result of climate change. The United States and Canada are currently renegotiating the Columbia River Treaty and incorporating ecosystem function into the agreement, which was originally designed for hydropower generation and flood control, is a central theme. Both parties agree that an adaptive management framework will be critical to achieving these multiple objectives and treaty renegotiations are widely seen as providing an opportunity to modernize the treaty by including consideration of the above issues.

On May 9, 2019 the UC Berkeley Canadian Studies Program, Institute of International Studies, and Riverlab hosted a workshop on incorporating adaptive management (AM) into a modernized Columbia River Treaty. Scientists, policy experts, and representatives of First Nations and Tribes from Canada and the US met at UC Berkeley to present and discuss principles of adaptive management, successful precedents, and consider issues of legal perspectives, climate change, and power management relevant to revising the 55-year old treaty.

Reflecting the conclusions of the workshop was a one-page communiqué sent to US and Canadian negotiators in Washington and Ottawa. A more detailed summary of the workshop recommendations will be posted in the near future.

The program for the workshop is available here, and PDF versions of the presentations from the workshop are available below: