About Rivers

Rivers are one of the greatest hazards in New Zealand’s outdoors. The topography of our landscape, combined with our weather, means that rivers and streams are a regular feature throughout our backcountry. Knowing how to identify if a river is unsafe, and the right techniques to use when crossing, are essential outdoor skills.

About rivers

Rivers change with time and weather.

• Widespread rain can cause large floods, sudden heavy rain can make side streams impassable and rain in a distant area or snowmelt can bring a new flow of water.

• Rivers can be impassable for hours or several days, however, the water level can drop as quickly as it rises.

Elements Of A River

Eddy lines: Where the water circulates behind boulders and back upstream, creating an unpredictable flow. It can be exhausting crossing these currents. It’s best to assess these currents upstream.

Strainers: Obstructions in rivers that water flows through but stops and holds objects that don’t, such as trees or fencing. The force of the river can trap objects and even people against them.

Recirculating water: Occurs when water drops over an obstacle, usually a rock, with such force it is pushed back up towards the obstacle. This creates strong currents flowing directly into the obstacle.

Sections Features

Upper and side streams: Have torrents in narrow channels with waterfalls and steep banks.

Be aware of run-outs, use boulders carefully or wade through deep pools. If water levels are high, wait for it to drop or turn back.

YOU AND RIVERS

River Types

Middle: Powerful river flow, affected by snowmelt and wide deep flows over boulders.

Carefully choose your crossing point. Take care with your footing as the steepness and flow can often make it them too powerful to cross.

Lower: Shingle beds and multiple deep and slow braided channels. Less sudden river level changes, but distant rain can increase levels. Levels can persist for many days.

Often deceptively powerful flows even if it looks slow. However, normally many places to cross. Give yourself the option to turn back if unsure.

• Rivers should never be underestimated, so it’s important to stop and think at each one.

• You need to decide whether to cross and further monitor your decisions throughout the whole process.

• Avoid flooded rivers and boulder hopping and use bridges/ cables/cages where possible.

• You need to understand how a river works, its characteristics and the recommended mutual-support method.

• Practical training or learning from other experienced people can boost your confidence and skills.

Before you go outdoors

Preparation is crucial. During trip planning identify points where you will need to cross rivers. For each, identify what your plan will be if the river is unsafe to cross.

• Look for where bridges are on your intended route

• Check the weather forecast and any track alerts using PlanMyWalk.nz

• Consider alternative routes or where you can backtrack if it is unsafe to cross

• Pack a shelter, warm clothes and food in case you have to wait out a swollen river. Put everything in a waterproof bag or dry sack, and spread important items amongst your group.

• Have a plan if you need to wait, such as take a communications device to tell your trusted contact you will be late.

Understand your route and look for: