The Buller is the major river of the west coast of the South Island and is named after Charles Buller who did much to further the colonisation of New Zealand. Its Maori name, Kawatiri, is believed to mean “deep and swift”, an appropriate description of the river with the greatest flood discharge in New Zealand. With a lowest measured discharge of 2,290 cusecs, the highest discharge is 437,000 cusecs, but little electric power has been generated from it or its many important tributary rivers, although schemes to do so are now being put forward.
From its source at Lake Rotoiti (1,997 ft), it flows in a changing but predominantly westerly direction for 105 miles to reach the sea at Westport, crossing the north-trending geologic and topographic grain of the country. Most of its catchment area of 2,510 square miles is mountainous and nearly three-quarters of it are clothed in native bush. For most of its length the river flows in steep-sided gorges with many rapids, crossing wide gravel-floored plains or valleys at Murchison, Inangahua and the coast.
Westport (pop. 5,464), has a typical bar harbour through which passes much of the output of the Buller coalfield. Both the main railway line and the main road to Canterbury follow the Buller Valley from Westport to Inangahua. The road from Westport to Nelson leaves the Buller at Kawatiri, and that to Blenheim follows the river past its source at Lake Rotoiti.
by Frederick Ernest Bowen, B.SC.(DURHAM), New Zealand Geological Survey, Otahuhu.