When devastating floods swept California last month, the community of Grayson – a town of 1,300 people tucked between almond orchards and dairy farms where the San Joaquin and Tuolumne rivers converge – survived without major damage.

In the minds of some townspeople and experts, that was thanks partly to the 2,100 acres (850 hectares) of former farmland just across the San Joaquin that have been largely restored to a natural floodplain.