Regional Estuary Monitoring Programme (REMP) intertidal sedimentation measurements, results and review of methodologies

Sedimentation within estuaries is a natural process but excessive sedimentation can lead to poor ecological health. To track patterns of contemporary intertidal sedimentation Waikato Regional Council (WRC) has been monitoring SAR in the Firth of Thames and Whāingaroa (Raglan) Harbour since 2003 as part of an estuarine State of the Environment (SoE) monitoring programme.

The programme measures sediment depth above plates buried in the intertidal flats. The purpose of these measurements is to track SAR in each estuary and to pair the measured SAR with monitoring of ecological health.

This report analyses the WRC SAR monitoring to assess the suitability of the methodology including spatial distribution of plates, temporal distribution of measurements and longevity of the plates. Sedimentation rates at each monitoring site have also been derived from the measurements.

This purpose of this analysis is to determine if the sedimentation monitoring programme has been effective and to establish principles around which a standardised sedimentation monitoring programme can be designed in the future, for the purposes of both SoE monitoring and for implementation of monitoring set out in Sea Change 2016. 

Report: TR 2019/04

Author: Stephen Hunt