Tunnicliffe, JDickson, MLongstaff, Kathryn2016-04-2720142014http://hdl.handle.net/2292/28678This thesis seeks to resolve the geomorphic variability exhibited by a series of six small fan-deltas along the Thames Coast, Coromandel, New Zealand. Although the fan-deltas occur within 30 km of each other on the same fault scarp, a variety of morphologies and sizes exist. A sediment budget approach has been employed to examine the components of the fan-delta system. By tracking the generation, transport, and deposition of sediments to the fan-deltas, the drivers of geomorphic variability can be described. The characteristics of the catchments influence the variation exhibited by the fan-deltas, but a larger catchment area does not produce a larger fan-delta. Rather, it is the catchment and localised slope, ruggedness, circularity and density that have the greatest effect on fan-delta geomorphology. The time frame of fluvial fan-delta sedimentation is 3 ka, with sediment delivery from the streams over this period calculated for the six study catchments: Waikawau 3.74 + 10⁷ m³, Te Mata 1.30 + 10⁷ m³, Tapu 6.72 + 10⁷ m³, Waiomu 6.14 + 10⁶ m³, Te Puru 2.92 + 10⁷ m³, and Tararu 6.52 + 10⁷ m³. The total sediment volumes for the fan-deltas are: Waikawau 1.36 + 10⁷ m³, Te Mata 1.38 + 10⁷ m³, Tapu 2.01 + 10⁷ m³, Waiomu 2.24+ 10⁷ m³, Te Puru 9.26 + 10⁷ m³, and Tararu 5.08 + 10⁷ m³. The assessed volumes of the fan-deltas deviate from the late-Holocene sediment delivery modelled. Te Mata has a fan-delta volume comparable to the sediment delivered over the late Holocene, potentially due to armouring of the fan-delta surface. Tararu has a fan-delta slightly smaller than modelled, although has a long history of land management. Waikawau and Tapu both have fan-delta volumes less than expected by modelling sediment transport, these sites have areas of low slope along their trunk streams allowing for within catchment sediment storage as well as finer sediment distributions permitting greater re-working of deposits. Waiomu and Te Puru both have fan-delta volumes in excess of their modelled sediment transport, indicative of debris flows delivering vast quantities of sediment in extreme events.Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher.https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htmhttp://creativecommons.org/licenses/by-nc-nd/3.0/nz/ThesisCopyright: The Authorhttp://purl.org/eprint/accessRights/OpenAccessQ112906121