(i.e. low hazard and high hazard) however, due to the characteristic of a Moruya River ‘severe flood event’ the Moruya River Floodplain Management Study suggests the incorporation of a further two hazard categories – very high hazard and extreme hazard, identified as:Low hazard Should it be necessary, people and their possessions could be evacuated by higher axle vehicles. Able-bodied adults would have little difficulty wading to higher ground. (d 0.8, v 2 & v x d 0.5). High hazard Possible danger to personal safety; evacuation by any vehicle could be suspect; able-bodied adults would experience difficulty in wading to safety; potential for significant structural damage to buildings. (0.8 < d 1.8, 2 < v 3 & 0.5 < v x d 1.5) Very high hazard Possible danger to personal safety on entering flow path; evacuation only possible by water craft; conventional structures would suffer structural damage. (d > 1.8, 3 < v 4 & 1.5 < v x d 2.5) Extreme hazard Water depths and flow velocities render any form of egress through the flood-path extremely hazardous; conventional structures, mobile homes, caravans could become buoyant and contribute to flood debris. (v > 4 & v x d > 2.5) Note: ‘v’ = velocity, ‘d’ = depth, ‘<’ = less than, ‘>’ = greater than, ‘ ’ = less than or equal to, ‘ ’ = greater than or equal to, ‘v’ x ‘d’ = velocity times depth. A D O P T E D F L O O D H A Z A R D C A T A G O R IE S P a tte r s o n B r itto n & P a rtn e rs P ty L td . 4 .0 0 0 H a z a r d R a n g e S c h e d u le s 3 .5 0 0 3 .0 0 0 Low: d 0 .8 , v 2 & v x d H ig h : 0 .8 < d V e r y h ig h : d > 1 .8 , 3 < v E x tr e m e : v > 4 & v x d > 2 .5 1 .8 , 2 < v 0 .5 3 & 0 .5 < v x d 4 & 1 .5 < v x d 1 .5 2 .5 V E L O C IT Y (m /s ) 2 .5 0 0 2 .0 0 0 EXTREM E 1 .5 0 0 V E R Y H IG H 1 .0 0 0 H IG H 0 .5 m /s m in im u m v e lo c ity 0 .5 0 0 LOW 0 .0 0 0 0 .0 0 0 0 .5 0 0 1 .0 0 0 1 .5 0 0 2 .0 0 0 2 .5 0 0 3 .0 0 0 D E P T H (m ) Figure 2 Determining hazard zones Moruya River Floodplain Development Guidelines 6