Rangitaiki

Geography

The river is 155 kilometres (96 mi) long, rising at an elevation of 740 metres (2,430 ft) above mean sea level, 32 kilometres (20 mi) east of Lake Taupō and 130 kilometres (81 mi) south of the Bay of Plenty coast. From its source in the Ahimanawa Ranges, at the confluence of the Tirikahu Stream and the outflow from Lake Pouarua, it flows for 64 kilometres (40 mi) across the Kaingaroa Plains towards Murupara.

Near the northern edge of the plains the river has been dammed by the Rangitāiki Dam, approximately 18 kilometres (11 mi) downstream of its confluence with the Wheao River. The dam diverts all but at least 0.5 cumecs into the Wheao and Flaxy power scheme, which discharges into Wheao River which joins the Rangitaiki upstream of Murupara.

History

The arrival of Europeans in the area lead to draining of wetland and low-lying areas along the river to create usable agricultural and horticultural lands. To support these activities the Rangitaiki Land Drainage Act was passed in 1910. Once the Rangitaiki plains approximately 40,000 hectares of wetland was drained and converted to farmland. At the same time the existing dual discharges of the river towards the Whakatāne River to the east and the Tarawera River estuary to the west were replaced by the cutting of a channel near Thornton to provide a new direct outlet for the Rangitaiki to the sea. Within a day of the new outlet being opened in May 1914, the level of the Rangitaiki in the lower sections of the Rangitaiki Plains area dropped by approximately1.5 metres (4.9 ft).

Tributaries

Heading downstream from its source, major tributaries of the river include the Otamatea River, Wheao River, which joins the Rangitaiki upstream of Murupara, the Horomanga River, which joins the Rangitaiki 12 kilometres (7.5 mi) north of Murupara, and the Whirinaki River, which joins the Rangitaiki 3 kilometres (1.9 mi) north of Murupara. The Horomanga and Whirinaki rivers rise in the Ikawhenua Ranges, also contribute relatively large flood flows (and quantities of shingle) to the Rangitaiki.