Hear Prof Matt Kondolf’s interview on the BBC’s Science in Action:
Category: News
May 6, 2022 – The Mekong Delta in Viet Nam could be nearly fully submerged by the end of the century if urgent actions are not taken across the river basin. Continuing with business as usual could drown 90% of this agro-economic powerhouse that’s home to nearly 20 million people – with immense local and global impacts.
Only concerted action by the six countries in the Mekong basin and better management of water and sediments within the delta could avoid such a devastating outcome, argues an interdisciplinary research team in a commentary published today in the journal Science.
Most of 40,000 km2 delta is less than 2m above sea level and is thus prone to climate change induced sea level rise. On top of that, actions in the delta such as over pumping of groundwater and unsustainable sand mining to construct expanding cities across Asia as well as rapid hydropower development upstream threaten the future of the most productive rice basket in Southeast Asia.
“It’s hard to fathom that a landform the size of the Netherlands and with a comparable population might disappear by the end of the century,” said lead author Professor Matt Kondolf from University of California, Berkeley. “Yet, like any river delta, the Mekong Delta can only exist if it receives a sufficient sediment supply from its upstream basin and water flows to spread that sediment across the delta surface, so that land is built at a rate that is equal or greater than global sea level rise.”
In the Mekong, water and sediment flows are increasingly endangered.
“Hungry for renewable energy, countries in the basin develop hydropower dams, which trap sediment, with little regard for system scale impacts. What little sediment reaches the lower Mekong could be mined to meet the demands of the burgeoning real estate sector in the region, which requires great amounts of sand for construction and land reclamation,” summarised co-lead author Dr Rafael Schmitt from University of Stanford.
But not all the blame can be put to upstream actions and global climate change induced sea level rise. In the delta itself, high dikes have been built to control floods and thus enable high intensity agriculture. This also prevents the fertile sediment from being deposited on the rice fields.
However, the drowning of the delta is not a fait accompli. There are steps that can be taken to allow dynamic, natural processes to help prevent the delta from further sinking and shrinking.
“The consensus amongst scientists on the scale and gravity of the threat to the Mekong delta is crystal clear, but it can be countered by ensuring the river’s waters remain muddy and murky with sediment,” said co-author Marc Goichot, WWF Asia/Pacific Freshwater Lead.
“Countries must choose a better development path for the Mekong river and region – one that is based on ambitious but feasible policies, which support a system-wide approach to energy, construction and agriculture that will build the resilience of the delta and benefit all the people and nature that depend on it. Business as usual would spell disaster for the delta,” added Goichot.
The team identify six measures that are feasible and have global precedents and would significantly increase the lifetime of the delta:
- Avoid high impact hydropower dams by replacing planned projects with wind and solar farms when possible and if not, building new dams in a strategic way that reduces their downstream impacts;
- Design and/or retrofit hydropower dams to enable better sediment passage;
- Phase out riverbed sand mining and strictly regulate all sediment mining, while reducing the need for Mekong sand through sustainable building materials and recycling;
- Re-evaluate intensive agriculture in the Mekong Delta for its sustainability;
- Maintain connectivity of delta floodplain by adapting water infrastructure; and
- Investing in natural solutions for coastal protections on a large scale along the delta’s coasts.
”Although the effectiveness of these measures, particularly if implemented in unison, is little disputed in the scientific community, major roadblocks exist for their implementation,” said Dr Schmitt.
Some of those measures would conflict with vested interests of certain actors, such as the sand mining industry and hydropower development, and some measures would require coordination among countries to account for system scale impacts and benefits of individual actions.
Countries would also need to agree that the sustenance of the Mekong delta is an important regional policy objective. In Viet Nam, where most of the delta is located, some recent policies try to counter some symptoms of a sinking delta, but there is little acknowledgement of the existential risk to the delta, nor ambition to work on truly systemic solutions.
Implementing the measures will require participation from national governments and international actors as well as new actors, including from the private sector and civil society. But together it is possible to save the delta from drowning.
“A Mekong delta that will thrive beyond the end of this century is possible – but it will require fast and concerted action in a basin that has been riddled by competition, rather than cooperation, between its riparian countries,” concluded Professor Kondolf.
The article, Save the Mekong Delta from Drowning, was published in Science 6 May 2022 and is available online at https://www.science.org/stoken/author-tokens/ST-468/full
Tuesday 12 May, 1030-1130
Social Science Matrix, UC Berkeley campus (8th floor of Social Science Building)
Floods are the most destructive natural hazard, both at the national and international scale, and they disproportionately affect people of color and the poor. To understand this uneven exposure to floods requires that we understand the history of land use and institutional structures that have resulted in current exposure and inequitable allocation of resources for flood protection and for post-disaster aid (‘procedural vulnerability’). One of the most critical agencies is the US Army Corps of Engineers, whose cost-benefit analysis approach tends to preclude flood risk management projects in poor communities. Panelists Danielle Zoe Rivera (UC Berkeley) and Jessica Ludy (US Army Corps) will draw upon their research on these topics and discuss pathways to improving on the current situation.
Please RSVP at https://forms.gle/RdFezN1PocEnzTFJ8 to reserve your spot.
Presented by Global Metropolitan Studies, the Social Science Matrix, and Riverlab, UC Berkeley.
Panelists:
Danielle Zoe Rivera is an assistant professor in the Department of Landscape Architecture and Environmental Planning in the College of Environmental Design. Rivera’s research examines movements for environmental and climate justice. Her current work uses community-based research methods to address the impacts of climate-induced disasters affecting low-income communities throughout South Texas and Puerto Rico. Rivera teaches on environmental planning and design, community engagement, and environmental justice. Her work has been published by the Journal of the American Planning Association, Environment and Planning, the Lincoln Institute of Land Policy, and the International Journal of Urban and Regional Research. She holds a PhD in Urban Planning from the University of Michigan, a Master of Architecture from the University of Pennsylvania, and a Bachelor of Architecture from the Pennsylvania State University. Prior to joining the University of California Berkeley, Rivera taught Environmental Design at the University of Colorado Boulder.
Jessica Ludy (she/her) is the Flood Risk Program Manager and Environmental Justice Coordinator for the San Francisco District US Army Corps of Engineers. Through the Army Corps’ “Technical Assistance Programs,” Jessica and her team partner with communities in the San Francisco District Area of Responsibility to identify and implement solutions for equitable, just, and sustainable climate adaptation. Jessica also leads the San Francisco district’s efforts to implement the federal government’s priorities to advance social and environmental justice. Jessica’s work is informed and inspired by collaborations and scholarship of researchers and colleagues both inside and out of the federal government, and by the decades of environmental and disability justice leadership from indigenous peoples, people of color, and other historically-marginalized groups. Jessica is a co-chair of the Social Justice and Floodplain Management Task Force at the Association of State Floodplain Managers. Prior to the Army Corps, she worked on flood risk management and floodplain restoration as an environmental consultant, a Fulbright scholar, and at nonprofits. Jessica completed her Master’s in Environmental Planning at UC Berkeley in 2009 where her thesis on flood risk perception behind levees sent her down a rabbit hole to change the way we ‘do’ flood risk management… forever.
US dams are filling with sediment much faster than most people realize. The result is that reservoir storage capacity is being depleted, threatening long-term sustainability of irrigated agriculture and municipal water supplies. There are techniques that can be used to extend the life of reservoirs, but these are rarely implemented. In a paper just published in Journal of Hydrology, Tim Randle and colleagues explain that we need a new paradigm to guide our management of these important components of our national infrastructure. You can access the paper here.
In process-based restoration, the objective is not to create a complex river form directly; instead, interventions are intended to “prompt” the natural processes to restore such forms. The improvements in ecological conditions are actually made over time by flowing water during floods (using the stream’s energy), and by the growth of riparian vegetation (using incoming solar energy). On the Aire River in Geneva, ecological function was restored to a formerly canalized river by providing the river with an espace de liberté. A grid of channels cut into the valley bottom allowed the river to freely flood, erode its bed and banks, and deposit bars, creating complex surfaces on which riparian vegetation established to support the food web of the riverine ecosystem. The diamond-shaped bits of land left between these channels (“lozenges”) gradually erode and evolve as the river migrates, creating complex channel forms. The Isar River in Munich restoration involved adding coarse sediment load, creating erodible bed and banks in place of formerly rigid boundaries, expanding process space for river migration, erosion, and deposition, and increased human access to the river over 8 km. Since restoration, natural transport of sediment has resulted in deposition of gravel bars, whose forms evolve during floods, supporting diverse habitats. The Isar and Aire Rivers provide compelling examples of process-based restoration meeting 4 criteria for process-based restoration: space, energy, materials, and time. They demonstrate the possibilities of urban river restoration to achieve both ecological and social goals through restoration of fluvial process. The paper is available under open access here.
The Symposium was held online on December 10th this year and featured a keynote talk by Brian Cluer and presentations of graduate student research. More than 130 participants attended the event. For more information, check out our symposium webpage!
More and more projects bill themselves as ‘process-based’. What distinguishes a real process-based project? Damion Ciotti and co-authors provide a concise summary in their new paper, ‘Design Criteria for Process-Based Restoration of Fluvial Systems’. The paper is freely available online from the journal Bioscience.
Rivers carry not only water, but also sediment. Yet sediment has been largely neglected in many studies of river history, and in current management plans. Profs Giacomo Parrinello and Matt Kondolf review how sediment has been treated (or ignored) by scholars in this introduction to a special issue in the journal Water History.
Riverlab is supporting the ongoing effort to remove four hydroelectric dams on the Klamath River, building on research conducted by Mark Tompkins and Matt Kondolf over a decade ago. An agreement among Tribes, NGOs, local stakeholders, the states of California and Oregon, and importantly, the owner of the dams, has paved the way for removing the dams starting in 2023, as reflected in this recent CBS News report. It will be the largest dam removal in the country and promises to benefit salmon runs in the river, which have been reduced by impacts of the dams and land use in the basin.