Decisions without Knowledge

Making decisions for coastal engineering, planning or management involves second-guessing how the coast might change in the future. How we make those decisions, and the information we should use to support them, should vary with each question!

Illustration of how few processes typical 'generic' hazard assessments include is suggested by comparison of the policy framework (SPP2.6) against vulnerability assessments along Busselton coast.

Assessment3	SPP 2.6 (2013)	Damara (2011)	Cowell & Barry (2012)	PNP (2012)
Hazard Likelihood	Possible	Possible	Worst Case	Worst Case
Area	State	Geographe Bay	Naturaliste-Rockingham
Mechanism
Storm Loss	P	P	P	P
Loss to Dunes		P	P	P
Beach Storage		P	P	P
Estuary Storage		P	P	P
Beach Geometry	(P)	P	(P)	(P)
Perched Beach
Reduced Supply		P
Nearshore Loss		P	P	P
Offshore Loss	P		P	P
Landform Instability		P		(P)
Alongshore Transfer	P	P	P	P
Beach Rotation		P	P	P
Sediment Cells				P
P indicates this mechanism has been directly represented; (P) indicates that this mechanism has been indirectly represented.

Identification of processes can also be obscured by the means coastal dynamics have been interpreted (see blog "Through the Looking Glass"). For example, use of vegetation lines usually understates seasonal fluctuations, and can limit identification of sustained beach loss, which can be a first step in the process of long-term coastal recession.