Injection of solids to lift coastal areas

Catastrophic flooding in coastal areas is an ongoing problem that may be aggravated by projected sea-level rise. We present a method of flood protection called SIRGE (solid injection for raising ground elevation), where the ground surface is raised by injecting sediment-laden slurry into hydraulic fractures at shallow depths. The injection process is repeated at adjacent locations to create a network of sub-horizontal, overlapping injections of solid material (hydraulic fractures). We argue that injecting sediment over large lateral distances would cause a lasting surface uplift that scales with the thickness of injected sediment at depth. We support this concept by an analysis showing that, in contrast to hydraulic fractures in petroleum reservoirs, hydraulic fractures in soft, shallow formations would typically grow in the toughness-dominated regime. It appears that the SIRGE process could be implemented to lift ground elevations in places such as Venice or New Orleans. Experimental and geological examples indicate that hydraulic fractures of suitable orientation and size can be created in areas with appropriate in situ stresses.