Coastal communities face risks from sea level rise, albeit over a long period of time based on current estimates of the IPCC Fourth Assessment Report. The Gold Coast, being built on sand and with many canal developments, could be considered particularly at risk. Suburbs of Sydney like Drummoyne and Concord on rivers like the Parramatta River face risks of inundation of low-lying areas such as parks (such as Timbrell Park and Majors Bay Reserve) reclaimed from mudflats at the heads of bays, or massive expenses in rebuilding seawalls to higher levels.