Channel Alteration is a measure of large-scale changes in the shape of the stream channel. Many streams in urban and agricultural areas have been straightened, deepened, or diverted into concrete channels, often for flood control purposes. Such streams have reductions in natural habitats for fish, macroinvertebrates, and plants than do naturally meandering streams. Scouring is often associated with channel alteration in particular, downstream of channelized reaches. Sediment Deposition measures the amount of sediment that has accumulated in pools and the changes that have occurred to the stream bottom as a result of deposition.
Deposition occurs from large-scale movement of sediment.
Heavy sedimet deposition can cause erosive flow energy to be diverted into streambanks, causing instability. It can also be evident in areas that are obstructed by natural or manmade debris and areas where the stream flow decreases, such as bends. High levels of sediment deposition create an unstable and continually changing environment that becomes unsuitable for many organisms. Depth Combinations is a way to measure the sequence of riffles and, in part, the complexity of habitat occurring in a stream. High sinuosity provides for diverse habitat and fauna, and the stream is better able to handle flow surges when the stream fluctuates as a result of storms.