This investigation created and tested a template to rapidly assess geomorphic river condition in urban settings. This extension to the River Styles Framework (R) (Brierley and Fryirs, 2005) entailed mapping the heterogeneity in bed material, habitat, and flow characteristics for different types of rivers, integrating parameters from geomorphology, ecology, and hydrology. Analysis was carried out at 27 sites in the Twin Streams catchment in West Auckland, New Zealand. The method successfully recorded the extent of degradation of physical structure following European settlement of the catchment. With the exception of one subcatchment, streams were found to be largely intact in the headwaters. Many of these headwater streams were found to be of exceptional quality, with high physical heterogeneity. Geomorphic condition is more degraded in downstream areas. Fine-grained sediment has smothered stream courses in the lower half of the catchment, covering bed material and creating homogenous structure and flow, decreasing quality of habitat for biota. In this more urbanized area, with more stormwater drains, riparian vegetation is limited and of poor to moderate quality. Understanding of geomorphic responses to human disturbance is critical in the design and implementation of effective management strategies that seek to improve the ecological condition of urban streams.

This study examines the evolution of a small urbanizing catchment in Waitakere City, New Zealand over the period since European settlement. Geomorphic changes are interpreted from the use of historical documents complemented by sediment analysis at eight sites throughout the catchment. Differing forms and rates of geomorphic adjustment are characterized for five different types of stream. Reach sensitivity to change and trajectory of change are related to the capacity for adjustment of differing stream types and their position within the catchment. These relationships are analyzed using the recovery diagram developed by Fryirs and Brierley (2000). Profound disturbance has been experienced, and streams have responded to a series of land use changes over a relatively short time frame (around 160 years). The system responded quickly to forest clearance and subsequent phases of pasture, horticulture, viticulture, and urbanization. Significant geomorphic recovery is under way along most stream courses. While Substantial increases in sediment yield are inferred, the fine-grained nature of these deposits has not significantly altered geomorphic features of headwater streams. In mid-catchment, benches have developed along overwidened channels. Prospects for geomorphic recovery are much more limited along lowland reaches, where Cumulative impacts have brought about Significant changes to river morphology, Such that recovery to predisturbance conditions is no longer a realistic prospect over management time frames (50-100 years). The relative geomorphic resilience Of this urbanizing catchment is considered to reflect the geologic imprint upon this landscape (a dissected volcano), the reforestation of headwater reaches within a short interval of initial clearance, and the location of urban impacts that are concentrated in the lower part of the river system.