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<br />1. Summary of Performance Index (PI) <br /> <br />e\ <br /> <br />The PI is a formula developed to evaluate whitewater boating course potential. The PI <br />. is a product of the percentage slope and the flow rate for the RICD in question: <br /> <br />PI=((hydraulic drop/boating course length) x flow rate) x 100 <br /> <br />Where: <br />The variables hydraulic drop and boating courSe length are measured in the same units <br />(i.e. feet), and flow rate is measured in cubic feet per second (cfs). <br /> <br />Hydraulic drop is the difference (in feet) between the water surface elevation just <br />upstream of the upstream control point (the beginning of the boating course) and the <br />water surface elevation at the downstream section of no hydraulic impact (the end of <br />the boating course). <br /> <br />The boating course lenath (in feet) is defined along the RICD stream reach centerline <br />starting at the most upstream control point and continuing through the most <br />downstream control point that defines the RICD reach. <br /> <br />eJ Downstream section of no hydraulic impact is defined as the stream cross-section at (or <br />just downstream of) the RICD reach where river and hydraulic parameters such as <br />velocity, shear stress, channel width, channel depth, sinuosity, etc. are first returned to <br />the pre-facility state, <br /> <br />The PI has several advantages as it can determine the potential of an undeveloped site <br />and a developed site on an equal basis. It does not rely on conveyance width, The PI <br />takes into consideration enhancing hydraulic head by impounding water at the start of <br />the course in order to achieve more drop [does this mean storage?]. The PI can be <br />easily verified by field measurement and by computational hydraulics. <br /> <br />A PI of 75 is considered as a guideline for a minimum threshold of "a reasonable <br />recreational experience" for a destination-oriented boating course whereas a higher <br />index number such as 500, for example, can be considered to have ""Olympic" or <br />"international" potential. <br /> <br />The PI is based on the premise that with efficient use of the flow rate the course <br />designer can create good recreational conditions by manipulating the hydraulics, <br />geometry, streambed and overbank areas of the stream. To do this, the site must have <br />design flexibility, or be readily modifiable to allow design flexibility, The acceptable <br /> <br />8 <br />