Paid personal/carers leave is available to staff (excluding casuals) not only where they are unfit for work due to injury or illness but also to provide care or support to a member of their immediate family or household, because of an illness, injury or an unexpected emergency.
A natural disaster such as the floods will fit within the classification of an unexpected emergency.
Therefore such staff may be able to access their personal/carers leave for these purposes.
For more information on your industrial relations obligations please see the following link at the Fair Work Ombudsman’s web site:
www.fairwork.gov.au/resources/fact-sheets/workplace-rights/pages/employment-entitlements-during-natural-disasters-or-emergencies.aspx