Te Papanui (Enderley) Storm Water

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Prior to European occupation of the Te Papanui–Enderley Area it was a ‘semi-swamp forest … with a border of manuka and cabbage tree swamp (p3*) …  Drainage of the area … had obvious effects on the bush’s hydrology. Where once it was common to find holes of 3-5ft of water and pooling, by 1955, drainage had prevented the accumulation of surface water (P5*) … it has been found that reduced soil moisture lowers the native species diversity and associated threatened species in this forest type’ (p4*).  Today the stormwater is directed quickly into sunless drains.

*Assessment of Vegetation Condition and Health at Claudelands Bush (Jubilee Bush; Te Papanui) – CBER Contract Report 113 – by Toni S. Cornes and Bruce D. Clarkson

The outcome is that ‘the water clarity is very poor and degraded. This stream enters Mangaiti from a culvert under Wairere Drive. The stream source is from the southern arm of the Kirikiriroa gully system that starts at Snell Drive’**. This is the outlet for the piped stormwater from the Enderley area. The map below shows the path of the piped stormwater. Peachgrove/Te Ara Rewarewa (see footnote) Road is the high ground, with stormwater flowing away from it. Not shown is the stormwater system south of Fifth Ave, which flows towards, then along, Wairere Drive before flowing under Snell Drive to the open stream through Porritt Park.

**Mangaiti Gully. An Ecologically Significant Area. A Management Plan: Jan 2020 (page 27)

Foot note: ‘Peachgrove Rd was formed upon an old walking track named Te Ara Rewarewa, which passed through a large forest block named Te Papanui’ – Pre-European History of Te Nihinihi (Hamilton East), by Wiremu Puke, from page 4 of ‘Hamilton East, Foundation for a Future City’, by Barry Lafferty.

The map above also shows high ground (ellipse) up steam of the highest drain. It is a map showing where the risk of flooding is lowest and were changing kerbs to provide more space for trees is easiest.  With the increasing likelihood of climate change, the value of water will increase, so the longer it is in our control the more we can get from it. So by making more space for trees we can get the benefits like, ‘Trees absorb the first 30% of most precipitation through the leaf system, allowing evaporation back into the atmosphere. Up to a further 30% of precipitation is absorbed back into the ground and taken in by the root structure, then absorbed and transpired back to the air. Some of this water percolates into the ground water and aquifer. Storm water runoff and flooding potential to urban properties is greatly reduced. One study estimated that for every 5% increase in tree cover area, run-off is reduced by 2%’ (see – ‘Street trees for living – benefits of street trees’).

High ground Dryden road

Lastly we should not under estimate a community lead tree planting initiatives. ‘30% of street trees die within the first few years of planting; in Lewisham it is 5%’. Source – Street trees for living / benefits of street trees

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