We should learn to value coastal sediment

Viewing coastal sediment (basically, sand, cobble and fine-grained material) as an asset rather than an afterthought is the focus of a recent article – making the case that how we manage sand is an issue of even greater importance now as climate change and human intervention are dramatically changing the way such sediment is needed and used along our coasts.

Authors Brett Milligan and Rob Holmes distilled their discussion from a 2016 look at the San Francisco Bay-Delta by scientists, engineers, regulators and policy-makers. The resulting piece, “Sediment is critical infrastructure for the future of California’s Bay-Delta,” is published in the spring 2017 issue of “Shore & Beach,” a peer-reviewed technical journal on coastal sciences published by the American Shore & Beach Preservation Association (ASBPA).

While this discussion focuses on the San Francisco Bay-Delta, the recommendations they examine for sediment management have application around the country. The authors examine the ways human actions affect sediment in the Bay-Delta, from erosion via deforestation, to entrapment by dams, to dredging in order to remove sediment from water bodies:

“In estuaries and other coastal regions, the sediment that experiences these manipulations is a crucial resource as it is the physical substrate underlying many highly valued landscapes… Ecosystems, communities, and economic activity rely on this dynamic infrastructure. However, in nearly all coastal and deltaic regions, sedimentary regimens have been highly altered by human intervention, radically affecting sediment distribution,” they said.

“Sediment availability is limited and shortfalls are exacerbated by the uneven geographic allocation of sediment — landscapes that need more sediment often cannot obtain it readily, while other landscapes experience excesses that generate problems such as unwanted siltation and associated management expenses.”

As sea levels change and coastal marshes and deltas subside, sediment sources are further impacted by human actions. Coastal sediment needs to evolve under such changing conditions and, the authors argue, the ways coastal and deltaic sediments are managed likewise need to change. As part of the summary of the Bay-Delta study findings, they offer a list of suggested policies, which include:

• Recognize and quantify the sediment shortfall: With an historical perspective and a quantity of the losses, you can better understand how sand movement has changed and resulting issues on the coast or delta that needs to be addressed.
• Learn to value sediment: Not only to recognize its evolution from spoil to asset, but to understand how policies about sediment that can impact its handling. It can no longer be viewed as something to dispose of, but needs to be recognized as a valuable commodity that needs to be better managed.
• Treat sediment as critical infrastructure: As the authors note, “…countless living and working communities are all built or dependent on the movement, management and sculpting of sediments.”
• Design holistic sediment systems: This requires better integration of “regulatory and planning authority over water, sediment, ecology, infrastructure and human settlement” by integrating decision-making. Sand management can’t be done piecemeal by a variety of regulators, but must be viewed and managed as a sediment system.
• Design for local conditions, and design for change: How do local shorelines change, and what impact does that have? What makes a piece of land valuable, and how might action (or inaction) affect that?
• Match sediment to the situation: The best replacement is the one that is most like what was lost, usually – and quality matters as much as quantity when it comes to sediment.
• Re-examine the goal of restoration at a time of great change: The goal of restoration is to return to a previous state – but which state should that be, given the increasing pace of coastal change? And what is the planning and restoration horizon – 20-years, 50-years or 100-years?
• Develop new technologies: Both in the hardware of machines and the software of new practices and protocols, using incentives and investment to boost innovation.
• Evolve planning and policy to meet new conditions and priorities: This can be a challenge when change comes faster than policies can evolve to respond to it.
• Organize sediment publics: Recognize that “the movement of sediment has political effects” – so building a constituency for sediment that includes all those affected by its movement is essential to sound decision-making.

The authors conclude that these recommendations “outline the contours of new thinking that can meet the sedimentary challenges… and emphasize directions for additional research…. Though written in response to conditions in the Bay-Delta, many of the principles… are broadly applicable in other deltas, bays, and estuaries.”

Founded in 1926, ASBPA is a 501(c)3 nonprofit that advocates for healthy coastlines by promoting the integration of science, policies and actions that maintain, protect and enhance the coasts of America. “Shore & Beach,” its peer-reviewed technical journal, has been published since 1933. For more information on ASBPA, go to www.asbpa.org, Facebook or www.twitter.com/asbpa.

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ABOUT ASBPA: Founded in 1926, the American Shore & Beach Preservation Association (ASBPA) is a 501(c)3 nonprofit that advocates for healthy coastlines by promoting the integration of science, policies and actions that maintain, protect and enhance the coasts of America. For more information on ASBPA, go to www.asbpa.org, Facebook or www.twitter.com/asbpa. For information, to change your email address or to unsubscribe from this list, contact us at managing@asbpa.org. A complete collection of Beach News Service articles is available for media access online at. https://asbpa.org/publications/american-beach-news-service/

NOTE: A PDF of the article is available by contacting ASBPA at managing@asbpa.org.