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<br />Rubble - Rough, irregular fragments of random size placed on a <br />streambank to retard erosion. The fragments may consist of <br />broken concrete slabs, masonry, or other suitable refuse. <br /> <br />Runout - See discharge. <br /> <br />Sack revetment - Streambank protection consisting of sacks (e.g. <br />burlap, paper, or nylon) fi I led with mortar, concrete, sand, <br />stone, or other available material placed on a bank to serve as <br />protection against erosion. <br /> <br />Sand - Soi I material that can pass the No.4 (4.76 mm) U.S. Standard <br />Sieve and be retained on the No. 200 (0.075 mm) sieve. <br /> <br />Scour - Erosion due to flowing water; usually considered as being <br />I oca I i zed as opposed to gene ra bed deg radat ion. <br /> <br />Sediment load - The sediment carried through a channel by streamflow. <br /> <br />Sediment vield - The total sediment outflow from a drainage basin <br />during a specific period of time. The outflow includes bed load <br />as wel I as suspended load, and usually is expressed in terms of <br />weight or volume per unit time. <br /> <br />Seepage - The slow movement of water through smal I cracks and pores of <br />the bank material. <br /> <br />Sill - A structure built across the bed of a stream to prevent scour <br />or head-cutting; see also grade-control structure. <br /> <br />Silt - Material passing No. 200 (0.074 mm) U.S. Standard Sieve that is <br />nonplastic or very sl ightly plastic and exhibits I ittle or no <br />strength when air-dried (Unified Soi I Classification System) <br /> <br />Sloughing - Shal low movement of a soi I mass down a streambank as the <br />result of an instabi I ity condition oat or near the surface (also <br />called slumping). Conditions leading to sloughing are: bed <br />degradation, attack at the bank toe, rapid drawdown, and slope <br />erosion to an angle greater than the angle of repose of the <br />material. <br /> <br />Soil-cement - A designed mixture of soi I and portland cement compacted <br />a a proper water content to form a veneer or structure that can <br />prevent streambank erosion. <br /> <br />Spur dike - See dike. <br /> <br />Stable channel - A condition that exists when a stream has developed <br />just the right bed slope and cross section for its channel to <br />transport the water and sediment del ivered from the upstream <br />watershed without any of the sediment being deposited or without <br />any soi I particles being removed from the bed or bank. <br /> <br />80 <br /> <br /> <br />