^1 



4 Is a functioning floodplain present? 

 Does your stream overflow its banks every few 

 years? If not, the stream may be changing 

 because of alterations in the watershed. Without a 

 floodplain, the stream's energy is concentrated in the 

 channel during flood flows. This increased energy may 

 either downcut the channel or erode the banks. 



To determine the edge of the bankfull channel, which is 

 the beginning of the floodplain, look for: 



• change in 

 vegetation 



• slope break 



• change in 

 particle size of 

 bank material 



• undercuts in the 

 bank 



• stain lines or 

 lower extent of 

 lichens on 

 boulders 



• top of stream or 

 channel bars 



Downcut stream 

 with no floodplain 



All of these characteristics 

 influence the personality of 

 your stream under natural 

 conditions. Stream types 

 may be changed by our 

 alterations and activities. 



Stream with functioning 

 floodplain 



5 



What is the channel shape? Channel shape is mostly influenced by: 



• quantity of water • gradient/valley slope 



• sediment load • amount and type of vegetation 



• type of bank and bed material • human activities that directly alter 



channel or watershed 



IBBSHI HBHS WKtKt^ 



Common channel shapes 



