Month: October 2018

River and reservoir sustainability in a monsoon climate: experience from Taiwan

02 November 1030a-1p, Rm 223 Moses Hall

Presented by Professor Hsiao-Wen Wang (National Cheng Kung University Taiwan), currently a Fulbright scholar at Berkeley working on conflicts between renewable energy and ecological values.  Like California, Taiwan has highly seasonal precipitation with high interannual variability, so reservoir storage is essential to provide water in dry months and dry years.  But the sediment yields in Taiwan are among the highest in the world, resulting in rapid filling of reservoirs, motivating Taiwan to implement sediment management measures sooner than elsewhere (Wang et al. 2018).  What can we learn from Taiwan’s experience?

This seminar is part of the interdisciplinary faculty seminar series, Water Management: Past and Future Adaptation, presented under the auspices of the UC Berkeley Institute of International Studies.  As both the developed and developing world confront intensifying demands on rivers and other water resources, impacts are evident from extractions of water for human uses, proliferation of dams, mining sediments from river beds, and intensified land-use impacts, all exacerbated by climate change.  Accelerated erosion of coasts and deltas (e.g., from sediment starvation, groundwater pumping, accelerated sea-level rise) are among the manifestations of these impacts.  Our seminar takes an interdisciplinary approach these challenges by examining how societies have adapted to variability in the past (uncertainty in water supply, flood risk, etc) and considers the tools we have to manage future variability in river flows and sediment loads, including variability in water supplies, increased flood risk, and the existential threat to many coastal areas.

 

References Cited

Wang, H-W, GM Kondolf, D Tullos, and W-C Kuo.  Sediment management in Taiwan’s reservoirs and barriers to implementation.  Water 10(8), 1034; doi:10.3390/w10081034

 

Managing sediment at the river basin scale: sediment-starved rivers and sand rights for the coast

Friday 26 October 1030-1p, Rm 223 Moses Hall.

The seminar will feature contributions from Carrie Monohan (Sierra Fund), Katherine Stone (MWGJF, retired), Mark Capelli (NOAA), and discussant Holly Doremus (Boalt).  Dams and instream aggregate mining interrupt the continuity of sediment in river systems, with consequences including coastal sediment starvation and consequent accelerated erosion and delta subsidence.  The concept of ‘sand rights’ has been proposed as a legal doctrine to protect downstream and coastal interests from interruption of their natural sand supply (Stone 2000).  In northern California, the legacy of sediment accumulation from 19th and early 20th century gold mining continues to present challenges, including problems created by the ‘debris dams’ (such as Englebright Reservoir on the Yuba) constructed to prevent sediment generated by hydraulic mining from moving downstream.

This seminar is part of the interdisciplinary faculty seminar series, Water Management: Past and Future Adaptation, presented under the auspices of the UC Berkeley Institute of International Studies.  As both the developed and developing world confront intensifying demands on rivers and other water resources, impacts are evident from extractions of water for human uses, proliferation of dams, mining sediments from river beds, and intensified land-use impacts, all exacerbated by climate change.  Accelerated erosion of coasts and deltas (e.g., from sediment starvation, groundwater pumping, accelerated sea-level rise) are among the manifestations of these impacts.  Our seminar takes an interdisciplinary approach these challenges by examining how societies have adapted to variability in the past (uncertainty in water supply, flood risk, etc) and considers the tools we have to manage future variability in river flows and sediment loads, including variability in water supplies, increased flood risk, and the existential threat to many coastal areas.

 

References Cited

Stone, K. 2000. Sand rights: a legal system to protect the shores of the sea. 29 Stetson Law Review 709, 732 (2000). 

 

Dams, Sediment Discontinuity, and Management Responses in Mediterranean River Basins

Friday 05 October 2018, ENS Lyon

By: Gabrielle Bouleau, Carole BarthélémyEmeline Comby, Joanna Guerrin

River basin management has mostly concerned management of water resources, with relatively little attention paid to the sediment continuity essential to maintain downstream channel functions and coastal features.  The sediment loads of most major rivers have decreased in recent decades as a result of extensive trapping of sediment by dams, increasingly manifest in accelerated coastal erosion and loss of delta lands. 

This conference examined three large rivers in southern Europe: the Rhône, Ebro, and Po.  All have headwaters in high mountain ranges and traverse Mediterranean-climate dominated basins.  All three have experienced afforestation of their mountainous headwaters since the 19th century, which has reduced erosion rates and sediment supply to the river system.  All three have been extensively modified and impounded for irrigation water supply, hydroelectric production, flood control, and navigation, mined for production of construction aggregate, and otherwise altered for human uses, and all three evince erosion and subsidence of sediment-deprived deltas. 

For each river, speakers reported on sediment discontinuity and sediment management from both geomorphic and environmental history perspectives (see programme below). One intervention, a social science perspective on sediment in the Rhône, was in the form of a half-hour video, which is available at the link above.  In discussion, speakers and participants from the audience drew comparisons among the three river basins, noting similarities and differences.  There was broad agreement among participants that the topic as framed by the conference merits further exploration. 

The conference was hosted by the Collegium – Lyon Institute of Advanced Studies and the CNRS Laboratory UMR 5600 Environnement Ville Société, and co-sponsored by the Agence Francaise de la Biodiversité, Eléctricité de France, and Companie Nationale du Rhône, in collaboration GRAIE and the Agence de l’Eau Rhône-Méditerranée-Corse.  The conference was coordinated with a broader research effort initiated by Professor G Mathias Kondolf (UC Berkeley) and Asst Professor Giacomo Parrinello (Sciences Po), The Social Life of the Sediment Balance: A Social and Geomorphic Approach to the Transformation of River Systems and Deltas, supported by the France-Berkeley Fund and a UC Berkeley Social Science Matrix-Sciences Po collaboration grant.

>>Conference programme

Adapting to sea level rise: Emerging governance issues in the San Francisco Bay Region

This recently published study by Pedro J. Pinto, Matt Kondolf, and Raymond Wong  (Environmental Science and Policy 90: 28-37) explores examples where actual implementation of SLR adaptation has led, or may lead to, the need to revise standards and practices or require uneasy choices between conflicting public interests.  While there is broad agreement in principle in the San Francisco Bay region on the need to adapt to sea-level rise through innovative approaches, actual implementation has proven difficult because of institutional complexity and communication challenges among stakeholders, including conflicting agency mandates and priorities.  Removing institutional barriers to adaptation will almost certainly require some agencies to adapt their policies, but path dependence is an obstacle.  The article is available for free download until 18 November here

A related paper explores why the SF Bay is so highly vulnerable to sea-level rise by comparison to the Tagus Estuary, Lisbon, Portugal, which is physiographically similar but was subject to a very different development history. A key difference was the role of the US Swamp Act of 1850, which turned tidal lands over from the federal government to states so the latter could encourage drainage and development, leading ultimately to a vast area of urban settlement subject to inundation in coming decades.  By contrast, in Portugal such tidal lands remained in the control of the crown, and were managed mostly for low-intensity agriculture, so today these lands are available to accommodate the landward migration of tidal wetlands with sea level rise, without conflicting with most urban land uses.  The paper,

“Evolution of two urbanized estuaries: environmental change, legal framework, and implications for sea-level rise vulnerability” (Water 8:535) is available online (open access) at http://www.mdpi.com/2073-4441/8/11/535/pdf

 

‘Horizontal levee’ with migrating ecotone. (adapted from HDR 2015)