Johnston, M.R.; O'Byrne, T.N.; Riddolls, B.W. 1978 Impact of geology on urban development, upper York Stream catchment, Nelson City. Lower Hutt: New Zealand Geological Survey. New Zealand Geological Survey report EG 299. 16 p.
Abstract: York Stream catchment is almost entirely within Nelson city, and is extensively urbanised particularly in its lower reaches. The stream drains the western and southern slopes of The Grampians (Flaxmore 392 m) and the eastern part of the Port Hills (Observatory Hill 173 m). In its upper reaches the stream flows to the west, but at Bishopdale it changes to a northerly course, flowing along the edge of the Port Hills and into Nelson Haven between Port Nelson and the Maitai River (Fig. 1). Between Bishopdale and the sea several tributaries drain the Port Hills. Between Bishopdale and the sea several tributaries drain the Port Hills. The upper part of the catchment consists largely of gentle to steep hillsides mostly in pasture with, particularly on The Grampians, extensive patches of scrub, gorse and locally in gullies regenerating bush. Many of the hillsides show evidence of instability. As the amount of land suitable or available for further urban development is limited, both within and adjacent to the city, York Stream catchment is being increasingly considered. Because development will increase the peak flows in the stream during storms, it is important that the maximum possible extent of urban development be determined beforehand so that the imminent re-design of York Stream drainage structures in the existing area is adequate to cope with the increased flow. The purpose of this report is to consider the limitations the geology will place on this development. (auth)