lowland area of east-central South Island, New Zealand. The plains cover an area of 150 by 45 miles (240 by 70 km) bordering on the Pacific Ocean. The Rangitata, Rakaia, and Waimakariri are the principal rivers, flowing east from the Southern Alps to cross the plains, which have hot summers and generally low humidity and a mean annual rainfall of less than 30 inches (750 mm).

Organized settlement of the area began in the 1850s with the introduction of merino sheep and the beginning of intensive farming for produce to ship to the goldfields of Victoria, Australia. The plains, the largest low-lying farm district of New Zealand, are well suited to mechanized agriculture for grains, pasture seed, and fodder crops, as well as fat-lamb raising. In the vicinity of Christchurch, the urban centre and chief outlet of the region, there is dairy, poultry, and fruit and vegetable farming and, around Ashburton, some use of irrigation for agriculture.