1.1 Location Of The Study Area The location of the study area is shown in Figure 1. It comprises part of the terrace to the south-east of the Manawatu River just opposite Palmerston North City centre. Almost all the area of the two drainage basins studied is within the boundary of Palmerston North City which has been expanded since 1967 to include land on this side of the river. This suburb is generally known as Aokautere. Both streams selected for study are secondary tributaries to the Manawatu River (Figure 2). They are here designated as Alton Creek, on the left, and Bolton Creek on the right, and the trunk stream they join before entering the Manawatu River is named Cliff Stream. The exact location of the study area can be found on NZMS 1 N149, the "Palmerston North" sheet, between grids E130 and E150, and N290 and N330. The township of Aokautere is about one mile northeast of the study area.