Towards an Understanding of Catchment-scale Sediment Dynamics: Cascades & Connectivity in Steepland Systems

Abstract

Steepland terrain is a characteristic of the Pacific Rim which must be better understood to mitigate and reduce risk associated with the cascade of sediment through short, steep, energetic catchments. The natural laboratory of New Zealand’s East Coast ranges provides examples to improve the understanding of linkages between slopes and channels in the upper part of steepland river systems at this critical point in the sediment cascade. These examples illustrate an array of processes contributing abundant sediment in concert with intrinsic and extrinsic controls conditioning catchment connectivity. Once generated from hillslopes, the residence time of alluvium is contingent upon the efficacy of erosion and transfer processes moving sediment along the conveyor. Impacts of point sources of sediment delivery may be long-lived.