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<br />1. Calculations show that the channel capacity at the critical <br />section (Qc) is significantly less than required to pass the <br />routed failure hydrograph peak (QR). The result is <br />significant damage to improvements such as houses, farm <br />structures, or commercial facilities. Since loss of life is <br />precluded, depth and velocity of flow adjacent to inhabited <br />improvements Dnlst be such that escape is possible. As a <br />benchmark, if the product of depth and average velocity is <br />less than 12, adults are assumed capable of wading to <br />safety. provided high ground is available and warning time <br />is sufficient. Permanent residences and other rnanmade <br />improvements are not expected to be moved from their <br />foundations. <br />2. The failure causes flooding into a downstream reservoir of <br />significant size, and ultimately results in the overtopping <br />and destruction of that dam. If overtopping of the lower <br />reservoir dam exceeds 6 inches in depth, failure is presumed <br />to occur for earthen structures. <br />3. Failure of the dam causes flooding and destruction of a <br />number of minor improvements (small roads, bridges, <br />agricultural lands, and diversion structures) which, in <br />aggregate value, constitute significant damage or economic <br />loss. This case is typical of larger reservoirs with <br />generally undeveloped downstream flood channels. Larger <br />reservoirs contain sufficient volume to create significant <br />flooding for a greater distance downstream than would a <br />reservoir of smaller volume. <br /> <br />22 <br />