Mangrove habitat expansion in the southern Firth of Thames: sedimentation and coastal hazards.

To come... Purpose: Mangroves have rapidly colonised intertidal areas of hte southern Firth of Thames during the last 50 years or so. Today, mangrove habitat occupies some 7 km2 of former intertidal flat between the Piako and Waitakaruru Rivers and 11 km2 in the southern Firth as a whole. Environment Waikato commissioned NIWA to undertake a study of mangrove habitat expansion and sedimentation in the southern Firth. The main objectives of the study are to: Reconstruct the historical sequence mangrove habitat expansion based on historical arial photography (1944-2005) and dated sediment cores. Quantify sediment accumulation rates (SAR) and changes in SAR resulting from mangrove colonisation and habitat expansion. Determine the role of mangrove habitat in mitigating coastal erosion and inundation hazards in teh southern Firth.

Analysis of and mangrove expansion from aerial photography. Shore normal transects of sediment elevation. Radioisotope and pollen analysis of sediment cores from transects.

Southern Firth of Thames

2004-2006

Mangrove expansion mapped using historical air photography: 1944, 1952, 1963, 1977, 1987, 1996, 2002, 2006. Shore normal elevation profiles were measured through the mangrove forest (Geodimeter Model 464 total station) to provide information on large scale coastal morphology, relate bed elevations to mean sea level and to provide information on coastal inundation hazard. Sediment cores were taken along transects for radioisotope and pollen dating. Full details in report. Frequency of collection: One-off data collection.

see report Gaps in collection: n/a Completeness: see report

Aerial photography held in digital form by EW - .jpg and .tiff formats.

Report freely available from Environment Waikato Sensitivity/Confidentiality: No confidentiality, public information.

Study completed.