page_title: Hauraki Plains
section_title: Drainage systems
hierarchical_section_title: Hauraki Plains / History / Drainage systems
caption_attribution_description: Piako river in New Zealand, Image taken of the piako river from the bridge
context_page_description: The Hauraki Plains are a geographical feature and non-administrative area located in the northern North Island of New Zealand, at the lower end of the Thames Valley. They are located 75 kilometres south-east of Auckland, at the foot of the Coromandel Peninsula and occupy the southern portion of a rift valley bounded on the north-west by the Hunua Ranges, to the east by the Coromandel and Kaimai ranges and the west by a series of undulating hills which separate the plains from the much larger plains of the Waikato River. Broadly, the northern and southern parts of the Hauraki Plains are administered by the Hauraki District and the Matamata-Piako District respectively.
  The alluvial plains have been built up by sediment deposited by the Piako and Waihou rivers, which flow north to reach the sea at the Firth of Thames, and earlier by the ancestral Waikato River. The resulting land is flat, peat-heavy, and partly swampy which has been converted into excellent land for dairy farming.
  Economically, the dairy farming is the leading primary industry, supported by other grassland farming.
context_section_description: Work started immediately after the passing of the Hauraki Plains Act. Controlling the flooding of the Piako River which overflowed at least once a year was crucial. This was achieved through the construction of stop-banks to prevent flood and tidal overflow.
  Farmers were required to dig drains, ranging from one to two metres wide, through their land. These drains connected to the main drains, which brought the water out and into the canals. Floodgates were installed to prevent the ingress of water into the canals, while allowing floodwaters to flow out of the system. Once the draining was completed over 75% of the wetlands of the Hauraki Plains was lost because of the draining. However, as a result of the drainage system the size of the wetlands declined to less than 25% of their original area.
  Once the land was mostly drained, scrub, logs and tree stumps had to be cleared, and the earth leveled, to convert it to pasture. The scrub and peat waste was burnt off.
caption: Control works in the floodplain of the Piako River played a big role in the draining of the Hauraki Plains
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