West Coast catchments condition and sediment yield assessment

This report is part of the Western Coastal Resource Survey. To provide an initial assessment of catchment conditions and sediment production, and of sedimentation patterns within Raglan, Aotea and Kawhia Harbours.

Identifies the geology, soils, vegetation, erosion, and physiography within each catchment; reviews hydrological data available for each catchment; determines suspended sediment concentrations within the harbours, and in streams over a range of flow conditions; determines sedimentation patterns within the harbours; and assess the nature of sediment impacts for the catchment and harbour environments.

Raglan, Aotea and Kawhia Harbours.

Raglan – E2676096 N6376563, NZMG, 1:20000, AREA Aotea – E2671819 N6354235, NZMG, 1:60000, AREA Kawhia – E2668841 N6344609, NZMG, 1:25000, AREA

Various

Geology, soils, erosion and vegetation are summarised from existing documentation. Streams are sampled for suspended sediment loads. Some of the streams have discharge data available. Assessment of sedimentation patterns was made utilising the Weggel (1983) technique where successive bathymetric charts are compared. Frequency of collection: One off

Results based on limited or insufficient flow, vegetation and geomorphology relationship data. Insufficient data to assess patterns erosion/deposition patterns in Aotea. Completeness: Limited gaugings for some streams, particularly for peak flow conditions. No rating curves for sampled streams. Incomplete coverage of harbours by bathymetric charts.

report, diagrams

See Department of Conservation

Finished