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Stream Channels (cont.) <br />All of these characteristics influence the personality of your stream under <br />natural conditions. Stream types may be changed by our alterations and <br />activities. <br />What is the channel shape? Channel shape is mostly influenced by: <br />• Quantity of water <br />• Amount and size of sediment particles <br />• Type of bank and bed material <br />• Gradient / valley slope <br />Is a functioning floodplain present? <br />• Amount and type of vegetation <br />and its associated root mass <br />• Human activities that directly <br />alter channel or watershed <br />Does your stream overflow its banks every few years? If not, the stream may be changing <br />due to alterations in the watershed. Without a floodplain, the stream's energy is concentrated <br />in the channel during flood flows. This increased energy may either downcut the channel or <br />erode the banks. <br />To determine the edge of the bankfull <br />channel, which is the beginning of the <br />floodplain, look for: <br />• Top of point bar <br />• Change in vegetation <br />• Slope break <br />• Change in particle size of bank <br />material <br />• Undercuts in the bank <br />• Stain lines or lower extent of <br />lichens on boulders <br />Downcut stream with no floodplain <br />Stream with functioning floodplain I <br />`' ' qT? <br />10