Hazards and Hydrology

The Power of Water

Rivers are filled with various obstacles. Many obstacles like holes, waves, and falls make the very rapids we find challenging and fun. Other obstacles like low head dams, sieves, undercuts, and strainers are features we really want to avoid. Scouting, either from the boat or on shore is one of the most important precautions we can take to avoid becoming another statistic. This article attempts to describe many of the river obstacles you may encounter on future river trips.

Many that are new to our sport grossly underestimate the power of water. It isn't unusual for a small stream to flow at 300 CFS. One CFS of water weighs 62.5 pounds. Since pins often occur where the river necks down, a very large portion of the stream's flow is pressing down on the trapped object. Over time, most boaters discover they need to work with the river instead of fighting a losing battle. The AW site's national river database: AW River DB is a great safety tool. It is color coordinated to let you know when your favorite streams are reasonably safe to paddle. River levels may also rise unexpectantly from isolated storms upstream. When paddling isolated runs, we need to pay attention to the overall river level and potentially take off the river when the level is too high for safe boating.

Subjective Versus Objective Hazards

Many boaters start when they are young and fearless. In the old days, we paddled in fiberglass boats that put a premium on running rivers clean (not hitting rocks). We had an extra incentive to be cautious. Today's boats are somewhat indestructible. Hitting rocks doesn't crack the hull anymore. We even use rocks for certain moves. The learning curve has also been significantly reduced. Many boaters are paddling class III whitewater in their first year of boating, some are even paddling class V runs. The above changes in our sport leave little time to develop sound river judgment and experience to recognize dangerous situations. Training, practice, and patience when "Stepping Up" are the best way to avoid becoming a statistic. Fortunately we have learned a great deal over the years and have access to much better information sources and excellent formal training. You may find this article on judgment interesting as well as the contained links for further study: Judgment.

Floods are a special concern for river running. Besides the extreme power of water associated with flooding, there are many other hazards that might not be as obvious. Floods often topple trees along their river banks. These trees form death traps called strainers or sweepers. In large floods, large trees and boulders float downstream with the rest of the river. Trash like old refrigerators, cars, and barrels often get swept into the river - all of which can form nasty entrapment obstacles. Storm runoff in metropolitan areas include sediment, oil, fertilizer, and herbicides. Overtaxed sewage treatment facilities often overflow in floods as well. Why bother paddling streams in severe flood stage when you can finally catch smaller streams that seldom run.

River Reading

A really fun part of our sport is boat scouting. Good intermediate boaters break down rapids into a series of eddy hops where they can get a good look at each section of the river in a safe manner. The following article contains a lot of resources on river reading: Reading Rapids.

Special Hazards

Many rivers have special hazards you need to pay close attention to. Some of these are a great deal of fun like holes and waves if you have the necessary skills. Even these fun features can be deadly if they become too large or have additional hidden hazards.

The following article is excellent and contains examples of many more features: Paddling Terminology.