Buller River

Buller
Buller River near Berlins
The Buller River system
Etymology	named for Charles Buller
Native name	Kawatiri (Māori)
Location
Country	New Zealand
Region	Tasman, West Coast
Cities	Saint Arnaud, Murchison, Westport
Physical characteristics
Source	Southern Alps (Saint Arnaud Range)
• location	Lake Rotoiti, New Zealand
• coordinates	41°48′10″S 172°49′20″E / 41.80278°S 172.82222°E / -41.80278; 172.82222
• elevation	620 m (2,030 ft)
Mouth	Tasman Sea
• location	Karamea Bight, New Zealand
• coordinates	41°43′45″S 171°35′20″E / 41.72917°S 171.58889°E / -41.72917; 171.58889
• elevation	0 m (0 ft)
Length	177 km (110 mi)
Basin size	6,350 km2 (2,450 sq mi)
Discharge
• average	429 m3/s (15,100 cu ft/s)
Basin features
Tributaries
• left	Travers, Hinemoatū, Gowan, Mangles, Matakitaki, Maruia, Deepdale, Inangahua, Blackwater, Ohikanui
• right	Hope, Owen, Matiri, Newton, Ōhikaiti, Ōrikaka

The Buller River (Māori: Kawatiri) is a river in the South Island of New Zealand.^[1] The Buller has the highest flow of any river in the country during floods,^[2] though it is only the 13th longest river; it runs for 177 km (110 mi) from Lake Rotoiti through the Buller Gorge and into the Tasman Sea near the town of Westport.^[3] A saddle at 710 m (2,330 ft) separates the Buller from the Motupiko River and that is divided from the Wairau River by a 695 m (2,280 ft) saddle, both aligned along the Alpine Fault, as is the top of the Buller valley.^[4]

Within the Buller Gorge and downstream from the Deepdale River joining, the Buller crosses from Tasman District into Buller District. The Paparoa Range separates the Buller River from the Grey River. A number of flora and fauna are found in the Buller catchment, many of these extending onto the slopes of the Paparoa Range.

The Buller River upstream from Murchison along with the Mangles River are popular for whitewater kayaking and recreational fishing,^[5] though the whole river can be kayaked; it is the only major river in the country with no hydro lakes,^[6] though a seismic survey for hydro power was done in 1973.^[7] For experienced canoeists the Ariki Falls section, between Murchison and Newton Flat, is also popular and novices can use it by carrying kayaks around the rapids, except when the river is very low and the rapids become unnavigable.^[6] The river is suitable for contact recreation approximately 95% of the time, though Tasman Council recognises it needs to be better because of the popularity of whitewater kayaking below Gowan Bridge.^[8]

State Highway 6 follows the river for 132 km (82 mi),^[9] SH63, upstream from SH6, for 23 km (14 mi)^[10] and the Stillwater–Ngākawau railway line runs through the Lower Gorge to Westport. State Highway 6 follows the river for much of its length.^[11]

This river has an annual mean flow of 454 cubic metres per second (16,000 cu ft/s), is estimated to have reached 12,700 m³/s (450,000 cu ft/s) in the 1926 flood^[12] and has the highest flood flow in the country of over 7,640 cubic metres per second (270,000 cu ft/s).^[2] 93% of the water comes from the western mountains, which make up only 38% of the catchment, and it is highest in summer, partly due to melting snow.^[13]