Tonle Sap Lake is unique in its ecological and cultural importance. In the rainy season, water flows upstream from the Mekong River to swell the lake to 4 times its dry-season extent, creating extensive shallow water habitat for fish. When the lake drains back to the Mekong through the Tonle Sap River, it creates one of the greatest fishing grounds of the world, providing protein to millions of people. Research by former Riverlab/Fulbright visiting scholar Chantha Oeurng and his student Ty Sok demonstrates evolving flow and sediment relations between the lake and the Mekong River. The just-published paper, Assessment of Suspended Sediment Load Variability in the Tonle Sap and Lower Mekong Rivers, Cambodia, is available for free download until late May from Catena here.
Two Riverlab researchers (Rafael Schmitt and Matt Kondolf) and two Italian colleagues (Simone Bizzi and Andrea Castelletti) have been awarded the 2021 Aspen Institute Italia Award for their joint research on “Improved trade-offs of hydropower and sand connectivity by strategic dam planning in the Mekong” . The scientists are working on this ongoing effort to reduce impacts of the global clean energy transition on rivers and livelihoods.
Building future green economy poses great economic and technical challenge for societies, in part because of the often-overlooked externalities of technology and infrastructure on people and the environment. In their research, the scientists used the example of hydropower development to demonstrate need and opportunity to resolve such conflicts through strategic spatial planning. Hydropower is a well-proven and cost-effective way to generate renewable energy. At the same time, dams can have catastrophic impacts on people’s livelihoods and the fundamental processes that underpin healthy rivers. Thus, there is great concern about the environmental impacts of future dams, mostly planned to energize socio-economic development in the global south.
The winning research demonstrated that strategic placement of dams, considering for the spatial heterogeneity of natural processes in rivers and the cumulative impacts of multiple dams, can greatly reduce dam impacts without compromising on energy generation and energy costs. That finding was derived by combining a novel computer model for evaluating large scale impacts of dams on rivers with state-of-the art tools for decision analysis. The study was based on the example of the Mekong River in South East Asia, where a massive hydropower development occurred in the recent past, and more development is foreseen in the near future. Results show that existing dams, exploiting around 50 % of the basin’s hydropower potential, have major impacts on the biophysical functioning of the studied rivers. The key finding of the study is that the same amount of hydropower could have been generated with much smaller impacts if dam sites would have been selected strategically such as to reduce their cumulative impacts.
While the results were derived for the Mekong River, the findings
have broad implications for renewable water and energy systems world-wide.
Globally, increasing conflicts between infrastructure and natural systems are
inevitable: Other forms of renewable energy create environmental impacts, more
water infrastructure will be required to meet domestic and agricultural water
demands, and industrialized countries must soon review their aging
infrastructure portfolios. In this context, strategic decision making, which
balances economic and ecosystem needs is crucial for an ecologic transition to
water and energy systems with minimal impacts on nature and maximal benefits
 The reasearch has been published by Nature Sustainability | VOL 1 | FEBRUARY 2018 | 96–104 |
Deliberate high-flow releases are increasingly made from dams to mimic effects of floods and interact with the channel to produce biophysical changes in channel characteristics, such as removing fine sediment from downstream aquatic habitats. These are a special case of environmental flows intended to mitigate geomorphic/ecological effects of dams, commonly termed flushing flows. In a new publication, Remi Loire and colleagues propose new terms for these high flow releases: morphogenic releases, or ecomorphogenic releases for flows intended specifically to improve aquatic and riparian habitats. The paper, published in Earth Science Reviews, reviews objectives of these flows, experiences gained from their implementation, and potential conflicts with environmental, socio-economic, and dam-operational issues. The paper is available until 21 February 2021 for free download here.
Loire, R, H Piégay, J-R Malavoi, GM Kondolf, and LA Bêche. From flushing flows to eco-geomorphic flow releases: evolving terminology, practice, and integration into regulated river management. Earth Science Reviews 213: 103475
Many cities worldwide now have available waterfront land, often in the city center, thanks to de-industrialization and concentration of navigation elsewhere. As cities seek to take advantage of this remarkable real estate, they may be prone to some classic ‘traps’ such as copying projects successful in another city but which fail in the new location due to differences in scale, topography, urban form, etc. In this recent publication, Pedro Pinto and Matt Kondolf present an idiosyncratic list of ‘wrongs’ that are evident in many such projects. The paper is freely available, via open access here.
Pinto, JP, and GM Kondolf. 2020. The fit of urban waterfront interventions: matters of size, money and function. Sustainability 12: 4079; doi:10.3390/su12104079
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.
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 published on the effects of road-induced sediment on aquatic ecosystems in developing countries of the tropics. Along the south bank of the Rio San Juan (Nicaragua and Costa Rica), attempts to build a road without engineering or plans resulted in massive failures and erosion in areas where steep slopes impinge upon the river bank. Pre-existing tributary streams received elevated sediment loads, creating new deposits on pre-existing tributary deltas. In some reaches 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. https://doi.org/10.1371/journal.pone.0242356
Held online this year over three days (9-11 Dec), the Symposium featured keynote talks, presentation of graduate student research, and expert panel discussions, with audience generally exceeding 100 attendees. The first day featured a keynote talk by Doug Shields, Stream restoration: What works and what doesn’t work. Stream restoration has become widely practiced in developed countries, but most restoration projects are not evaluated after implementation and there is no consensus regarding evaluation criteria. Dr Shields reviewed meta-analyses of stream restoration evaluations to determine factors that contribute to success. The second day’s keynote, by Professor Martin Doyle (Duke) on Stream restoration and compensatory mitigation explored how current mitigation practices have resulted in a homogenization of channel form across North Carolina and other areas of the nation. The third Keynote, by Jack Schmidt (Utah State University) synthesized work from across one of America’s great rivers, Restoring the Colorado River. Student research projects addressed a wide range of issues, from monitoring post-fire impacts on salmon-bearing streams, a spring-fed river at the heart of a Texas city, carbon sequestration in woody debris stored on a reconnected floodplain, indigenous perspectives on stream restoration, steelhead trout habitat in an urban stream, river restoration projects in China, etc.
You can now click on each of the session titles below (highlighted in blue) to download the video recordings.
Wed 9 December
Stream restoration: What works and what doesn’t work, by Doug Shields
Fire & water : geomorphic baseline in Mill Creek, by Molly Oshun, Morgan Cooney & Adrienne Dodd
The San Marcos: a spring-fed river in the heart of the city, by Lilly Byrd
Carbon sequestration benefits from a reconnected floodplain, by Britne Clifton
Buffer zones for XiXi Wetland, Hangzhou, by Jingyi Chen & Karen Jin
Doug Shields, Neil Lassettre, Celina Balderas-Guzman
Thurs 10 December
Stream restoration and compensatory mitigation, by Martin Doyle
Riparian habitat vs vegetation encroachment in the Salinas River, by MaFe Gonzales
Understanding the waters and the grove: Cerrito Ck in Blake Garden, by Camille Thoma, Dulce Rivas
Indigenous frameworks for restoration: San Leandro Ck, by Janet Le
Kristen Van Dam, Susan Schwartz
Fri 11 December
Restoring the Colorado River, by Jack Schmidt
The urban gauntlet for steelhead trout, by Ali Parmer, Derek Morimoto, & Rebecca Kaliff
A restoration on the Yongding River, Beijing, by Yifan Feng
Social connectivity of Houtan Wetland in Shanghai, by Peixuan Wu, Youtian Wang & Zhehang Li
Karen Pope, Rafa Schmitt, Sandra Lee
Invited Speaker Biographies
Doug Shields, Jr, has over 40 years of professional experience in environmental and water resources engineering. Doug was a Research Hydraulic Engineer first with the US Army Engineer Waterways Experiment Station, and then with the National Sedimentation Laboratory (USDA-ARS) until 2012. He is currently a consulting engineer with his own firm and with cbec eco engineering of West Sacramento, and Adjunct
Professor at the Department of Civil Engineering, University of Mississippi. He has authored or co-authored more than 300 technical publications, and conducted research on physical aspects of streams and rivers, habitat
rehabilitation, and water quality across the Continental US.
Martin Doyle is a Professor at Duke University focused on the science and policy of rivers and water in the US. His work ranges from fluid mechanics and sediment transport to infrastructure finance and federal water policy, including a 2015-2016 assignment in the Department of Interior helping to establish the Natural Resources Investment Center, an initiative of the Obama Administration to push forward private investment in water infrastructure, enable water marketing, and increase the use of markets and conservation banks for species conservation. As the 2010 Clarke Scholar at the US Army Corps of Engineers, he worked on regulatory policy for mitigation banking and jurisdiction of ‘waters of the US.’ He is author of The Source (WW Norton, February, 2018), a history of America’s rivers, and the forthcoming is Streams of Revenue: The Restoration Economy and the Ecosystems It Creates (co-authored with Rebecca Lave).
Jack Schmidt is the Janet Quinney Lawson Chair in Colorado River Studies at Utah State University, where he leads the Center for Colorado River Studies. He has devoted 30 years of research to the Colorado River and the
relationship of ecosystem health and the dams, reservoirs, and diversions associated with river management. He is a leading authority on the managing the Colorado River in the Grand Canyon, and recently stepped down as Chief of the US Geological Survey’s Grand Canyon Monitoring and Research Center, a position he had held since 2011. In both his university and government research, Jack has worked to encourage collaboration between federal and state agencies, tribal interests, non-governmental organization and academic institutions. He received the National Park Service Director’s Award for Natural Resource Research in 2009.
Celina Balderas Guzman is a PhD candidate in the Department of Landscape Architecture and Environmental Planning at UC Berkeley. Her dissertation work focuses on the future of coastal wetlands in San Francisco Bay under climate change and implications on ecological restoration and adaptation planning. Additionally, she conducts collaborative research on the relationship between stormwater quality and watershed characteristics in the United States. Celina’s research bridges environmental science with urban planning. Her previous degrees are in urban planning, urban design, and architecture from the Massachusetts Institute of Technology.
Neil Lassettre is a Principal Environmental Specialist in the Environmental Resources section the Sonoma County Water Agency (Sonoma Water), where he provides cross-disciplinary project management and technical support to projects in water quality, flood control, and environmental compliance. He received his PhD in Environmental Planning from UC Berkeley in 2003, was a Fulbright Fellow in Lyon, France from 2003-2004, and consulted for ten years prior to joining Sonoma Water. He leads effectiveness monitoring for the Dry Creek Habitat Enhancement Project, a joint project with the Army Corps of Engineers, National Marine Fisheries Service, and California Department of Fish and Wildlife to enhance salmonid habitat below Warm Springs Dam.
Sandra Lee is an environmental planner with PhD from Tsinghua University and MSc from Wageningen University. She has conducted interdisciplinary research on sustainable management of water across Europe and Asia, notably in eastern China (e.g., water resource and environmental planning, costal lowland revitalization planning and design, rural-urban ecological planning, climate-resilient urban design, community participatory planning and design). She is currently an associate researcher with Riverlab at UC Berkeley.
Karen Pope is a research aquatic ecologist at the USDA Forest Service, Pacific Southwest Research Station. Karen focuses on linking hydrological processes with biological responses to inform stream and meadow
restoration. Current research includes the effectiveness of floodplain restoration techniques in recovering conditions for aquatic biodiversity and understanding how invertebrate and amphibian communities are affected
by aquatic restoration projects, pathogens, and invasive species. She has a PhD in Ecology from UC Davis and MS in Biology from Cal Poly San Luis Obispo.
Rafael Schmitt is a senior scientist at the Natural Capital Project at Stanford University. Rafael’s research focuses on modeling and managing water, energy, and ecosystem services provided by the world’s large rivers.
As part of the Natural Capital Project, Rafael is currently working on developing models to quantify the role of nature to provide sediment and nutrient retention as well as flood and landslide prevention. Rafael also
researches on strategic planning and trade-off analyses to find better trade-offs between dam environmental impacts and their economic benefits.
Susan Schwartz graduated from UC Berkeley in 1965 (economics). She was a newspaper reporter and editor in Fairbanks, Seattle, Akron, and Miami, taught scientific writing, and wrote three minor guides on natural history
before returning to Berkeley to raise a family. She became involved with Friends of Five Creeks more or less by chance, and has co-headed or headed the all-volunteer group for 20 years. Friends of Five Creeks works with
urban nature in many ways, including a lecture series, walks, other events, publications, interpretive signs, mapping and monitoring, and seeking to influence government. However, most if its effort is hands-on, generally in areas neglected or abandoned by public agencies, including after previous “restorations.”
Kristen Van Dam is an Ecologist with the East Bay Regional Park District. She supports the Park District’s Fuels Management Program, including coordinating environmental compliance, biological monitoring, and
program mitigation. Kristen has 17 years of experience in ecological restoration and management, including 12 years as an ecologist with the Urban Creeks Council and five years with the Park District, and holds a Master of Forestry from UC Berkeley.
About the Class and Symposium
Restoration of Rivers and Streams (Landscape Architecture and Environmental Planning 227) is taught by Professor Matt Kondolf. Offered annually since 1992, it is the longest-running course devoted to river restoration at a major research university. This graduate-level course emphasizes understanding of underlying goals and assumptions of restoration, and integration of natural and social science into restoration planning and design. Students review restoration plans and evaluate completed projects. In addition to lectures and discussions by the instructor, students, and guest lecturers drawn from the active restoration community, the principal course requirement is an independent term project involving original research and a presentation at this Symposium. The symposium is normally held in-person, but this year has moved to an online platform.
We are excited to share a new Riverlab article, linked here, published this month in the Journal of Hydrology. This work advances current understanding of the controls on hydrological connectivity of impervious surfaces to downstream channels and storm-sewer networks and presents new methods of their estimation.
Connected impervious areas – those impervious surfaces that contribute directly to runoff in a storm network or stream – are a better indicator of hydrologic response, stream alteration, and water quality than total impervious area. Most methods for quantifying connected impervious areas require major assumptions regarding the definition of ‘connection’, potentially over-simplifying the role of variable climates, slope gradients, soils conditions, and heterogeneous flow paths on impervious surface connectivity.
In this study, we present a new metric, hydrologically connected impervious areas (HCIA), to refer to spatially explicit (mapped) estimates of the proportion of impervious surfaces that are hydrologically connected to the storm sewer system or stream network. HCIA is comprised of impervious surfaces that contribute directly to the storm-sewer network and are physically connected, Aphys, or those that contribute indirectly and are therefore variably connected (Avar) (see Figure 1). The degree to which Avar is “hydrologically connected” is represented with a coefficient, ϕvar, that ranges between 0 and 1, with 0 representing full connectivity (i.e. all runoff infiltrates downslope), and 1 representing no connectivity (i.e. no runoff infiltrates downslope).
Using a combination of hydrologic modeling in the PySWMM, a python interface for the EPA’s Stormwater Management Model, and machine-learning regression tree analysis, we evaluate the controls on ϕvar across varing soil types, slopes, rainfall scenarios, antecedent soil moisture conditions, as well as amounts of impervious and pervious areas. Figure 6 shows that of the factors tested, soil texture (panel A), fraction of downslope pervious area ϕperv (panel B), soil moisture (panel C), and precipitation (panel D) are sensitive, while total area (panel D), width of impervious area (panel F), and slope (panel G) are insensitive parameters.
To assist with dissemination of these methods in practice, we apply the regression tree in a geospatial tool for estimation of HCIA in ungauged urban catchments. We test the tool in a case study to an urban sewershed in Colorado, and find that the contribution of Avar to HCIA (compared to the contribution of Aphys) varied across the precipitation and soil moisture conditions. Avar contribution to HCIA was low at low precipitation depths and increased rapidly with increasing precipitation and initial soil moisture conditions (see Figure 9).
Overall, our results suggest that, for catchments consisting of highly impermeable soils, Avar contributes to HCIA such that HCIA approaches the total impervious area, but for catchments with highly permeable soils, Avar does not contribute significantly to HCIA, and thus the physically connected impervious area ( Aphys) could be used as a suitable surrogate for HCIA. In between these two extremes, however, lies a wide range of conditions that call for detailed and spatially explicit estimates of Avar connectivity.
Sytsma, A., Bell, C., Eisenstein, W., Hogue, T., & Kondolf, G. M. (2020). A geospatial approach for estimating hydrological connectivity of impervious surfaces. Journal of Hydrology, 591, 125545. https://doi.org/10.1016/j.jhydrol.2020.125545 >>link to paper
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
Our Riverlab events have been cancelled for Spring 2020 due to COVID-19.