The catchment is dominated by mountains and hill country.
The mountains are characterised by strong lithologic and structural control of landforms, with dip and scarp topography common and notable areas of karst on Mt Owen and Mt Arthur.
The hilly terrain can be grouped into three types:
About 67% of the catchment has slopes greater than 15º.
There are limited areas of gently sloping floodplain, terraces, and fans.
The Motueka-Riwaka Plain
The two most extensive flat areas are the 40 km2 Motueka-Riwaka Plain near the coast and the 33 km2 upper Motueka.