Science Fair Project Encyclopedia
|Extent|| Motuiti to Waikawa Beach;
Tasman Sea to Tararua Ranges
Unlike many other districts, it has a distinct identity, so much so that "The Horowhenua", as it is usually called, is regarded more as distinct region than as part of the region of Manawatu-Wanganui, which is how it is officially designated.
Located north of Wellington and Kapiti, the district stretches from slightly north of the town of Otaki in the south to just south of Himatangi in the north, and from the coast to the summit of the Tararua Ranges.
Much of the area was once an extensive wetland and the centre of a substantial flax industry. It has been progressively drained and converted to productive farmland, with a mixture of loam and peat based soils. Some parts of the wetland, particularly those around Lake Horowhenua are being returned to their former state as a conservation area, with the help of local Maori.
Foxton is of historical note as the main town in the Manawatu in the early years of European colonisation, and the centre of a large flax industry. Horticulture and dairying are now the main forms of primary industry in the district, and secondary industries in Horowhenua include manufacturing (especially clothing manufacture) and food processing.
Much use is made of artesian water supplies. The northern part of the district, around Opiki, is situated above a series of aquifers. These are vertically separated from each other by layers of less permeable material, known as aquacludes . Within each aquifer, there may also be pockets of less permeable material, known as lenses. In descending order, the aquifers below the Opiki district are the Foxton, the Himatangi, and the Opiki Aquifers. Over its whole extent, which is much wider than the Opiki area, the Foxton Aquifer lies mostly between 30m and 60m below ground level. Around Opiki it is shallower, generally between 24m and 35m below ground.
Although not unique, the Foxton Aquifer in this area has the relatively uncommon quality of being under pressure so that when a bore is tapped into it, the water rises under its own pressure and will flow above ground; ie there is flowing artesian water. The head varies with ground level but can be as high as about 2.5m above ground level. The level to which it will rise defines the potentiometric surface . For obvious reasons, the farmers and residential users who have bores tapping into the Foxton Aquifer regard this as a most useful attribute. In many cases it can avoid the necessity of pumping water from the bore and, for those even more fortunate, it can avoid the necessity of reticulating the water around farm properties by pumping systems. There are natural seasonal fluctuations in levels and pressures, but there is evidence that, even in times of extended dry periods, no property in the area loses positive pressure entirely, although some decline to a critical point. As an aside to that point, it is inevitable that the existing bores in the area will have reduced the potentiometric surface from its original level, and that future permitted bores will continue that trend. There must come a time when those properties which now become critical at those times will lose flowing artesian water.
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details