Burge, P. I. (2007, January). Sedimentation in the Avon-Heathcote Estuary/Ihutai: An analysis of past and present studies.
Commissioned by the Avon-Heathcote Estuary Ihutai Trust and Environment Canterbury in the summer of 2006-2007, this report is a literature review examining sedimentation in the estuary. Its purpose was to determine where future studies of sedimentation in Te Ihutai needed to be directed, and it focused on studies published since the last major review in 1993.
The review is split into four sections, Section 1 being an introduction. Section 2 examined studies of sediment size distribution, erosion, and deposition patterns across the estuary. It was noted that useful quantitative data on this was last collected in the 1980s, therefore Section 2 concluded that a new survey of bed levels and surface sediments was needed to accurately determine changes in sediment distribution patterns over the last 20 years.
Section 3 examined studies of nutrient enrichment, organic matter concentrations, and heavy metal and organic contaminants within estuary sediments. It determined that robust heavy metal contamination studies were last conducted in the 1980s, while information on nutrient enrichment and organic contamination was extremely limited. Consequently, regular monitoring of heavy metals, organic contaminants and nutrients in estuary sediments was recommended.
Section 4 examined the input of sediment and contaminants from major terrestrial sources: the Avon and Heathcote Rivers and the Christchurch Wastewater Treatment Plant (CWTP). It suggested that multi-year sampling of storm events for suspended sediments in the rivers was needed to accurately calculate long term sediment input to the estuary.