Errata for HEC-18, HEC-20, and HEC-23
(As of September 6, 2001)
HEC-18 (Fourth Edition)
p. xii | Definition of k_{s}: k_{s} = Grain roughness of the bed, m (ft). Delete: "Normally taken as the D_{84} of the bed material." |
pp. 2.8 and 2.9 |
Delete last sentence p. 2.8 which continues on p. 2.9 that reads "If the magnitude of the 500-year flood is not available from a published source, use a discharge equal to 1.7 times the Q_{100}" and substitute the following: "For guidance for a particular state in determining the magnitude of the 500-year flood, contact with the U.S. Geological Survey Water Resources District office is suggested." |
p. 5.15 |
Example Problem 3, y_{2} equation: Add a close parenthesis so denominator reads (0.0003)^{2/3} (91.4)^{2} |
p. 6.1 |
First paragraph, 3rd line should read: "...cohesive or noncohesive..." |
p. 6.4 | Definition of K_{4}:
Delete ..."and Table 6.4." |
p. 6.6 |
Last sentence in bold should read: The minimum value of K_{4} is 0.4. Delete: "and it should only be used when V_{1} < V_{ic D50}." |
p. 6.7 |
Equations 6.9 and 6.10: F should be Fr_{1} |
p. 6.13 |
Equation 6.14: K_{s} in numerator and denominator should be k_{s} Definition of k_{s} should read: k_{s} = Grain roughness of the bed (normally taken as the D_{84} for sand size bed material and 3.5 D_{84} for gravel and coarser bed material, m (ft) |
p. 6.23 |
Last paragraph, first sentence should read: "The angle of repose of cohesionless material..." |
p. 6.28 |
Equation: "1n" in numerator and denominator should be "ln." "K_{s}" in denominator should be "k_{s}." |
p. A.9 | Appendix A, Table A.7: For the Kinematic viscosity column, the values should be multiplied by 10^{-5} not 10^{-4}. |
p. E.3 |
Appendix E, title should be: Sturm Abutment Scour Equations |
pp. E.4 - E.7 |
Throughout the Appendix: The subscript "o" should be "0" (zero), i.e. "Y_{fo}" should be "Y_{f0}" The subscripts "l" and "i" should be "1" (one) i.e., "V_{ml}" should be "V_{m1}" and "V_{mic}" should be "V_{m1c}" |
p. E.5 |
Second paragraph, 5th line should read: "the denominator in the above equation..." |
p. E.6 | Item 6c: First line should be: "Compute the critical velocity..." |
p. E.7 |
Item 8a: Under "where:" change the "x_{a}" in the equal to less than expression to "X_{a}" Item 9 should read: "...scour depth, y_{s}, from Equation E.1." Item 10, last paragraph, last line should read: "equation presented in Section E.3." |
p. E.8 |
Reference #2, second line: Delete "September" and add "FHWA Report No. FHWA-RD-99-156, McLean, VA." |
p. F.3 | First paragraph, second line should read: "The equations and method are presented..." |
HEC-20 (Third Edition)
p. xi |
Definition of : = Density of water, kg/m^{3} (slugs/ft^{3}) |
p. 6.15 |
Definition of k_{s} should read: k_{s} = Grain roughness usually taken as 3.5 D_{84} for gravel and coarser bed material, m (ft) |
p. 8.4 |
Reference #46 should read: 46. "Leopold, L.B. and ..." |
p. A.9 | Appendix A, Table A.7: For the Kinematic viscosity column, the values should be multiplied by 10^{-5} not 10^{-4}. |
HEC-23 (Second Edition)
p. ix |
Definition of : = Fluid density, kg/m^{3} (slugs/ft^{3}) |
p. 7.17 |
Figure 7.11 Flexible Conduit description should read: "l" UV RESISTANT RUBBER HOSE" |
p. 8.4 | Reference #46 should read... 46. ..."Geosynthetic Design and ..." The same change should be made to this reference in: DG1, p. DG1.16 DG3, p. DG3.6 DG4, p. DG4.23 DG6, p. DG6.27 DG7, p. DG7.9 DG12, p. DG12.21 |
p. DG6.3 | Title of Design Guideline 6 should read: Concrete Armor Units |
p. A.9 | Appendix A, Table A.7: For the Kinematic viscosity column, the values should be multiplied by 10^{-5} not 10^{-4}. |