 It's for this reason that many of Lismore's homes are built elevated, in a fashion known as "hiset" and why Lismore has extensive levee systems to protect the city from all but the worst floods.The frequency of flooding is due to several contributing factors.One is the relatively high rainfall in the headwaters of the system (The Rummery Park Rain Gauge is the Wettest in NSW) and the unusual geomorphology which means that the River flows away from the sea for a significant distance then south after reaching Lismore before joining the Richmond River which eventually flows north east to the Tasman Sea.