RIFFLE RUN POOL SERIES

They provide habitat for aquatic organisms including fish, amphibians, insects, birds, and plants. Streams transport water and sediment gathered from the surrounding watershed. Stream channels, their near riparian areas, wetlands, and floodplains are part of a network essential to ecosystem health. River scientists often refer to the pool tail or the tailwater in reference to the tail-like surface water formation that marks the transition from glide to riffle. A glide is the section of the stream coming out of the pool, from deeper to shallower as it approaches the next riffle. In high flows, the opposite is true: as a result of increased sheer stress вЂ“ the force exerted by water on the stream bed that increases in deeper areas вЂ“ the pool is scoured and bed materials deposit on the riffle, rebuilding and reinforcing it. Low flows deposit sediment and cobble in pools and scour them away from riffles. Pools have a near-flat water surface (the product of a very low slope) and are much deeper than the stream's average depth. Pools form on the outside bends of meanders between riffles they also occur behind large protruding boulders in the channel or along the banks. Runs follow riffles they are deeper with a less turbulent water surface. They also provide a good starting point if you are looking for a place to cross a stream. Riffles control the stream bed slope and elevation and they serve as a gateway and exit to pools in a meandering system. Water moves faster over riffles even at low flow, removing fine sediments and oxygenating the stream. Riffles are relatively shallow, and the slope of the water surface is steeper compared to the average water slope of the stream.

RIFFLE RUN POOL SERIES

In most Ausable streams, riffles are dominated by larger cobble or boulders forming a single or short series of rib-like structures from bank to bank. In each case, these stream features interact with the bed, banks, and floodplain of a stream to create a network that supports wildlife habitat, oxygenates water, and continuously rebuilds stream form and function. Higher slope streams tumbling down a hilly or mountainous grade follow a step-pool sequence вЂ“ such as John's Brook in its higher elevations or Cascade Brook. In a sinuous lower slope stream meandering across a valley floor вЂ“ such as the East Branch in Keene Valley or the West Branch along River Road вЂ“ riffles, runs, pools, and glides will appear in sequence. Healthy streams have repeating features that maintain channel slope and stability. Or, knowing where those pools get deepest, might influence where you cast your line in search of a trophy trout. What's behind that? Why isn't it all one continuous feature? And if you've been faced with the challenge of crossing a stream, finding the appropriate stream feature can help you cross safely with minimal effort. If you've ever spent time along a stream of any size, you may have wondered about the alternating patterns of flat versus tumbling water - what river scientists refer to as features.

Riffle run pool