Laserfiche WebLink
<br />certain measures of water depth and water velocity which may be con- <br />sidered minimum, maximum, and optimum for an activity; and (3) the <br />measurement of water surface area which meets certain requirements of <br />depth and velocity is a viable method of describing recreation potential <br />for instream recreation uses. <br /> <br />, <br /> <br />This method is comprised of four components: (1) computer simula- <br />tion of a stream reach, (2) determination of the combinations of stream <br />depth and velocity, (3) determination of a composite probability-of-use <br />for each combination of depth and velocity, and (4) calculation of a <br />weighted usable surface area. <br /> <br />.: <br /> <br />1. <br /> <br />Simulation of the Stream. The stream reach simulation model <br />ut i1 i zed in thi s approach uses several cross sect i ona 1 tran- <br />sects, each of which is subdivided into subsections. For any <br />stage (water surface elevation) the mean depth and velocity of <br />each subsection is calculated. Typically, a transect would be <br />established across a pool, a riffle, and an intermediate area. <br />Together these cross sectional measurements would represent a <br />stream reach which may extend several miles. ln Table 2 a 100 <br />foot length of stream is represented. <br /> <br />.'. <br /> <br /> Table 2. Depth velocity matrix showing total <br /> surface area of stream in square feet. <br />Depth (ft) Velocity in feet per second <br /> <0.5 0.5-1.0 1. 0-1. 5 >1. 5 Total <br /> <1 500 400 100 0 1,000 <br /> 1-2 600 700 800 300 2,400 <br /> 2-3 100 300 500 100 1,000 <br /> >3 0 0 100 0 100 <br /> Total 1,200 1,400 1,500 400 4,500 <br /> <br />2. <br /> <br />Distribution of Combinations of Depth and Velocity. The <br />output of the stream reach simulation model is in the form of <br />a matrix showing the surface area of a stream having different <br />combinations of depth and velocity. Table 2 illustrates a <br />depth velocity matrix. The outlined number in the upper left <br />matrix cell refers to 500 square feet per 100 feet of stream <br />having a combination of depth less than 1.0 foot and velocity <br />less than 0.5 foot per second. This figure is the-5um of the <br />areas within the stream reach with this combination of depth <br />and ve 1 oc i ty. <br /> <br />, <br /> <br />5 <br /> <br />.~.~",:",-- <br /> <br />I <br /> <br />",'. <br />