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Hurunui / Hawarden Gap, II (III)

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Hurunui

Info

Class: 
II (III)
Portage?: 
No
Put in: 
Bottom of Maori Gully
Take out: 
Mandamus confluence

From the bottom of Maori Gully (just above Surveyors Stream) to Mandamus confluence. The valley widens after the gorge of Maori Gully but still passes over occasional bedrock to produce features including drops and wave-trains. The Hawarden Gap itself is a short, narrow bedrock constriction that can produce some challenging hydraulics

Gauge (External): 
Hurunui @ Mandamus (NIWA)
Upstream of: 
Mandamus to SH7

Comments

hugh's picture

The Hawarden Gap section of the Hurunui is a good day trip for advancing novices and intermediates. It departs from the road for most of its length, and the scenery, while different from the spectacular upper Hurunui valleys, is still on a grand scale and is quite diverse. This run is best with moderate flows, but for kayakers still finding their way, the Gap can be a frightening obstacle if the flows are over 50 cumecs, so the flows between 25 and 50 cumecs are best for less experienced paddlers. At flows above 70 cumecs the rapids from the Glenrae to the Gap create a series of excellent surfing wave trains, and the Gap is a mass of turbulence. Above 100 cumecs the water overwhelms the bedrock on the LH side of the Gap and a whole new shape of rapid develops, with the principal feature being a full width hydraulic of some power, followed by turbulent narrows with substantial laterals.

This trip is the section of the Hurunui River from the bottom of Maori Gully to either of two takeouts; carry up the Mandamus River to the road, or further downstream at the The Peaks farm access (permission required). You can put in by running Maori Gully, or if you want to keep the level of difficulty more consistent, at the get out of the Maori Gully run. The river flows through open grazing country in a broad single channel with occasional short rapids created by bed rock and the occasional large boulder. The river is a consistent Grade 2 until you get the L bank tributary Glenrae River, where the banks close in and wave trains develop. These get bigger with higher flow but would not reach Grade 3 until the flow is over 80 cumecs.

The Hawarden Gap itself is a short narrow gap about 2-3m wide into a large pool. The drop is worth a scout (on the L) if you have novices in the party. As the flow increases the Gap can get easier but the vortex in the pool below becomes more powerful, and this is where the capsizes and swims usually occur. With novices it pays to set up protection here, as there are two rapids below this pool which can cause more swims. The next rapid is on a RH bend with an undercut and 100m further on is a centre boulder which creates a hole at some flows.

A wet exit at the Gap can mean a relatively safe but scary swim of up to one kilometre, hence the need to cater for novices from the outset.

The narrow gorge gets easier and then opens out in to Grade 2 water, with the only hazard being a LH bend in a further short gorge immediately above the Balmoral Irrigation offtake. This bend has a back eddy on the right which is hard to get out of at any flow.

The Mandamus joins the Hurunui on the L and if the flow is low you can carry your boats up the river to Tekoa Road. This is a long shuttle, so most parties continue to The Peaks farm on Creans Road, which is accessible from Powers Road turnoff from the Lake Sumner Road. This is private road and permission is required. The Balmoral offtake has a road but the gate is usually locked.

The Glenrae River which is normally a clear creek of around 1-5 cumecs, has been known to flood dramatically, so if the lower Hurunui is muddy and high, with a high gauge reading (>100cumecs) on the Ecan website, and Maori Gully is clear and looks below 50 cumecs, the Glenrae is in flash flood, and the Hawarden Gap will be Grade 4 and not suitable for novices or intermediates. The Gap and the narrows that follow can be portaged on the L along a farm road.

This section is rafted and is a good raft trip at moderate and higher flows. Jet boaters like to test themselves on the "Hawarden Chutes". Keep well clear as there is no room for jet boats to avoid other craft.

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