> Willow wood becomes rock-hard underwater and almost doesn’t deteriorate. Research in the late 1960s showed that most fascine mattresses submerged for more than 100 years — some dating from the early 1820s — remained intact.

> Unlike most other tree species, willow tolerates saltwater and (temporarily) wet feet. As such, the coppice plantations could use land that was not suitable for agriculture.

> On impoverished soils, the Dutch planted alder trees between the willow trees. The falling leaves of the alder fertilised the soils and increased the lifespan and production of the willow trees.

Building long-lasting critical infrastructure using locally-sourced, carbon-negative resources! I have no idea about dykes specifically but I suspect today someone pitching a public works project based on woven willow would be laughed at -- and instead we would insist on pouring some reinforced concrete, using carbon-intensive cement, and it would begin falling apart from rusted rebar in 15 years.