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Ngā Tohuwhenua Mai Te Rangi: A New Zealand Archeology in Aerial Photographs

Irrigation

Irrigation

In the arid regions of New Zealand, particularly Central Otago, the earliest irrigation was a by-product of the reticulation of water to the goldfields. As the gold-rushes petered out, there was a break-up of the large estates, as gold-miners and other immigrants sought land for settlement. A water supply that could provide for cropping and pastoralism was in place, but it was under-utilised or used wastefully. On alluvial flats and the high terraces, near the sites of the main gold-mining activity, the practice known as 'wild-flooding' was employed. The water flow was diverted by the placement of a simple canvas screen in the race. The water would both warm and irrigate the grass in dry frosty conditions, following the ancient principle of the English water-meadow, 17 probably well known to early pastoralists. Contemporary wild-flooding is shown in the vertical aerial photo page break
The high terrace and coastal flats at Nukutaurua, Māhia Peninsula

The high terrace and coastal flats at Nukutaurua, Māhia Peninsula

At centre is the pā, Waipuna, showing as a distinct rectangle of ditch and bank. On the high terrace to its left is a remnant of the double ditch and bank of another pā. Running along the foot of the slope (commencing bottom right) is a ditch and bank fence. The view is from the south-east, and was taken from above the pā, Maungakahia.

graph of Northburn, near Cromwell, an example which I detected while scanning photographs for gold-mining, the topic of the following chapter. Another early form of irrigation was the practice of flooding from more or less parallel series of ditches following the contour. Again some former head races for gold-mining allowed this to be done.

In other seasonally arid areas, such as South Canterbury, schemes specifically for irrigation were not introduced until the 1930s. Their need had been anticipated, but construction did not occur until subsidised labour became available during the depression. A practice known as 'border-diking', designed to achieve economic use of the water, came into use at this time. 18 This practice involved the systematic construction of ponding areas by the raising of banks on near-level ground, such as is depicted in the oblique photograph of Northburn in the following chapter.