River Crossings

Safety and rivers in the New Zealand backcountry

Getting swept away in rivers is the biggest cause of fatal accidents in the sub-alpine area of New Zealand. With huge fluctuations in rainfall, seemingly innocuous rivers and side streams that drain even moderate catchments can be fatal. The New Zealand back country has been carved out to shed water. When it is dry or raining lightly the wide rivers can be virtually empty. But with rainfalls that sometimes approach 200+mm (8 inches) a day, watercourses become torrents.

If this was not bad enough, loose rock and scree that is precariously poised on hillsides often chooses heavy rain to let go and take out large tracts down valley. These slips are common. Heavy rain is when 20mm or more occurs in less than 6 hours.

In December 2002, separate accidents killed two people when slips occurred in a heavy rain event in Mount Aspiring Park. These accidents were on well bridged, popular tracks. Most of the main tracks are well bridged, but all tracks are dangerous in heavy rain.

Safety Tips

• Weather reports in huts will specifically refer to heavy rain warnings. If heavy rain is happening or forecast, it means it is time to stay put. Going out in average rain is fine, but when it is really pouring (you know it when you see it) find safe shelter and wait it out. Remember the small trickle that you step over can prevent you from making it back to the hut a couple hours later.

• Judge river and stream crossings for the weakest and smallest members of the party. Tall heavy people have a big advantage.

• There are lots of books and brochures that show you methods for crossing rivers such as linking arms etc… These are fine if you are trying to avoid falling over and getting wet, but if it being used to keep a member of your party from being swept away, you are asking for an accident. If conditions are such that a member of your party can get swept away to an uncertain fate – turn back or find another crossing. If you don’t know if it is safe – turn back.

• If you are going to make a crossing but are unsure, have a single member of the party do a short crossing to determine the strength of the current. Leave the pack behind and slowly walk out into the current, if the footing starts to get unstable, turn back. Don’t discover the current is too deep when you have the entire party in the river with their packs on.

• Always wear your hiking boots if it is a larger crossing. Loose rocks can crush your feet.

• Think about what is down stream. Once water reaches the height of your pack you will become buoyant and begin heading downstream regardless of where you want to go.

• A crossing with rapids or rocks downstream will be unsafe while the same crossing that will sweep you onto a sand bar or pool can be safe.