Coastal Sedimentation: What We Know and the Information Gaps
Report: TR 2008/12
Author: Hannah Jones
This report aims to bring together available information on coastal sedimentation, summarising what is known and identifying what is not known about the sources and the effects of coastal sedimentation.
Sedimentation in estuaries is a natural process that can be accelerated by changes in land use or land management within the catchment or by development of structures within the estuary. Estuaries are under increasing pressure from coastal development or catchment activities and development, such as farming, subdivision and vegetation clearance. Estuaries on the east coast of the Coromandel Peninsula are at high risk of infilling because of the erosive nature of their catchments (steep topography and frequent high intensity rainfall events) and the physical nature of the estuaries (sandbars or barriers narrow the harbour entrances). In addition, major land use changes have occurred on the Coromandel Peninsula following European settlement. Large scale deforestation in the late 19th century was followed by conversion to pasture (early to mid 20th century) and then exotic production forestry became established from the 1950s until present.
Some studies have provided information that is applicable to all east coast Coromandel estuaries.
|The scope and structure of this report||2|
|The life of an estuary||2|
|The process of sedimentation in estuaries||3|
|The effects of sedimentation on estuaries||6|
|Effects on plants||6|
|Effects on benthic animals||7|
|Sources and delivery of sediment||9|
|Sediment yield from catchments studied||13|
|Sediment cores: X-Radiograph and isotope techniques||17|
|Storage in streams||18|
|How does land use (production forest, native forest or pasture) impact on erosion?||18|
|Harbour and catchment comparison||43|
|Appendix 1: Catchment land cover||55|
|Appendix 2: Whangamata sediment core||56|