Floods are mainly caused by the overflowing of rivers, lakes, and reservoirs due to heavy rains, ice jams, snowpack melt, or the collapse of dams. Coastal flooding can be caused by hurricanes, tidal surges, tsunamis or freak high tides.
In mountainous or flat terrain, distant rain will be channelled into gullies, ravines and canyons, turning a quiet stream-side campsite into a rampaging torrent in minutes. If you’re planning a trip into a wilderness region that is prone to flash floods, always be sure to check the weather forecast before and during the expedition.
Avoiding Flash Floods
- Keep alert for signs of heavy rain both in your location and upstream,
- Choose campsites away from creeks and other low-lying areas,
- Do not stay in an area where your only exit crosses a stream,
- Watch for water levels rising quickly and becoming muddy,
- Know where high ground is and how to get there quickly,
- If you hear a roaring sound upstream, this may be a flood wave moving rapidly towards you!
Caught in Flash Flood
- Find a route to higher ground,
- Avoid walking through moving water. As little as 15-20 centimetres of moving water can knock you off your feet
- Use a stick to check the ground and depth in front of you,
- Avoid downed power lines.
- Don‘t drive through flooded areas. As little as 60 centimetres of water can sweep away vehicles. If your vehicle stalls in a stream – abandon it!
- Do not drink the water – it is likely contaminated.
- Do not attempt to cross unless there is no alternative,
- Look for the shallowest, and most level section,
- Don’t cross if more than knee deep,
- Use a walking stick to balance and test depths,
- Keep boots on for better grip – dry boots are no good if you are dead!
- Turn at a right angle with your back towards the opposite bank and shuffle sideways, testing each foothold,
- Avoid outside of river bends where the current is fastest,
- Once one person from the group has crossed – a rope can be used for greater stability and safety.