Hollever, J., & Bolton-Ritchie, L. (2016, July). Broad scale mapping of the Estuary of the Heathcote and Avon Rivers/Ihutai. Environment Canterbury.

This report from Environment Canterbury (ECan) is the last of a series of projects which conducted broad-scale habitat mapping of non-vegetated areas of estuarine intertidal flats in Canterbury. Its purpose was to document key intertidal habitats in the estuary, provide sedimentation and eutrophication data, identify and prioritise at-risk estuaries for monitoring in Canterbury, classify estuary ecosystem health, provide baseline data for future projects, and provide accurate data for planners and decision makers in Canterbury.

Following the 2010-11 Canterbury earthquakes, there were significant changes in sedimentation, bathymetry and hydrodynamics in the Ihutai estuary. Overall, this report found many similarities and differences in mapping data of the Ihutai estuary from 2002 and 2016. In both years the eastern and southern edge of the estuary was dominated by firm mud and sand, while the centre section comprised predominantly shell banks and sand. In 2016 there appeared to be a loss of aquatic vegetation and increases in very soft mud and sand upstream of Bridge Street. However, the report noted that identified differences could be due to differences in mapping methodology and the extent of ground truthing.