Flooding happens when land is inundated with water. Rivers can flood through high rainfall and urban areas can be flooded from blocked or inadequate drainage.
Effects of floods
Floods are an integral part of a river’s natural cycle and transfer sediment through the river system to the surrounding floodplains. This makes the floodplains such as the Hutt Valley and Ruamahanga Plains fertile and attractive places to settle and farm.
Floods can be caused by heavy localised rain or by storms spread across the region.
Historic floods in the Wellington region
In February 2004 heavy rain across central New Zealand caused flooding in the Manawatū-Whanganui, Marlborough and Wellington regions. These floods damaged property, infrastructure, and about 75 homes and properties needed to be evacuated.
Flash floods can be caused by heavy localised rain in a river’s catchment, which can present a hazard to people downstream who are unaware of the rain upstream.
Risk of floods
Floods are the most frequently occurring natural hazard in the Wellington region, they present a high risk due to the large scale damage that can be caused by a flood. Flooding can also disrupt transport routes if roads become impassible.