Sedimentation patterns and catchment use change recorded in the sediments of a shallow tidal creek, Lucas Creek, Upper Waitemata Harbour, New Zealand

Publisher Website
Google Scholar
Abstract
Radiocarbon dating and pollen analysis have been used to date and identify changes in Lucas Creek catchment use, recorded in Holocene subsurface sediments. Holocene marine sedimentation began about 6500 years before present. Where the sediment column is thickest, maximum net sedimentation rates for the estuary are recorded as less than 1.5 mm/y for pre‐Polynesian times (6500–700 years B. P.) when the catchment was forest‐clad. Above this level the pollen record shows that the 1 mm/y net sedimentation rate accompanying forest clearance during Polynesian settlement (700–110 years B. P.) subsequently tripled to 3 mm/y with logging, gum digging and land clearance accompanying farming during European times (A. D. 1841 to present). Since 1854 the main channel areas of Lucas Creek have experienced no detectable sedimentation or erosion. Present‐day deposition is estimated as averaging less than 2 mm/y on the tidal flat areas. Future catchment urbanisation is expected to double sediment input to Lucas Creek estuary and result in increased sediment accumulation in the lower, wider estuarine reaches and embayed areas. Larger and more frequent flood events are likely to minimise sediment accretion or cause scour in the narrow upper reaches. Urban debris will be a problem unless controlled at source.

This publication has 6 references indexed in Scilit: