| 
 
 
 
APPENDIX A:  TABLES 
 
 
 | TABLE A-1   PROPERTIES OF WATER IN SI UNITS. |  
| Temperature (°C)
 | Specific Gravity
 | Density (g/cm3)
 | Heat of Vaporization
 (cal/g)
 | Viscosity | Vapor Pressure |  
| Absolute (cp)
 | Kinematic (cs)
 | (mm Hg) | (mb) | (g/cm2) |  
| 0 | 0.99987 | 0.99984 | 597.3 | 1.790 | 1.790 | 4.58 | 6.11 | 6.23 |  
| 5 | 0.99999 | 0.99996 | 594.5 | 1.520 | 1.520 | 6.54 | 8.72 | 8.89 |  
| 10 | 0.99973 | 0.99970 | 591.7 | 1.310 | 1.310 | 9.20 | 12.27 | 12.51 |  
| 15 | 0.99913 | 0.99910 | 588.9 | 1.140 | 1.140 | 12.78 | 17.04 | 17.38 |  
| 20 | 0.99824 | 0.998211 | 586.0 | 1.000 | 1.000 | 17.53 | 23.37 | 23.83 |  
| 25 | 0.99708 | 0.99705 | 583.2 | 0.890 | 0.893 | 23.76 | 31.67 | 32.20 |  
| 30 | 0.99568 | 0.99565 | 580.4 | 0.798 | 0.801 | 31.83 | 42.43 | 43.27 |  
| 35 | 0.99407 | 0.99404 | 577.6 | 0.719 | 0.723 | 42.18 | 56.24 | 57.34 |  
| 40 | 0.99225 | 0.99222 | 574.7 | 0.653 | 0.658 | 55.34 | 73.78 | 75.23 |  
| 50 | 0.98807 | 0.98804 | 569.0 | 0.547 | 0.554 | 92.56 | 123.40 | 125.83 |  
| 60 | 0.98323 | 0.98320 | 563.2 | 0.466 | 0.474 | 149.46 | 199.26 | 203.19 |  
| 70 | 0.97780 | 0.97777 | 557.4 | 0.404 | 0.413 | 233.79 | 311.69 | 317.84 |  
| 80 | 0.97182 | 0.97179 | 551.4 | 0.355 | 0.365 | 355.28 | 473.67 | 483.01 |  
| 90 | 0.96534 | 0.96531 | 545.3 | 0.315 | 0.326 | 525.89 | 701.13 | 714.95 |  
| 100 | 0.95839 | 0.95836 | 539.1 | 0.282 | 0.294 | 760.00 | 1013.25 | 1033.23 | 
 | Source:  Linsley, R. K. et al. (1982). Hydrology for Engineers. 3d. ed., New York: McGraw-Hill. | 
 
 
 | TABLE A-2   PROPERTIES OF WATER IN U.S. CUSTOMARY UNITS. |  
| Temperature (°F)
 | Specific Gravity
 | Density (lb/ft3)
 | Heat of Vaporization
 (Btu/lb)
 | Viscosity 1 | Vapor Pressure |  
| Absolute (lbs/ft2)
 | Kinematic (ft2/s)
 | (in Hg) | (mb) | (lb/in2) |  
| 32 | 0.99986 | 62.418 | 1075.5 | 3.746 | 1.931 | 0.180 | 6.11 | 0.089 |  
| 40 | 0.99998 | 62.426 | 1071.0 | 3.229 | 1.664 | 0.248 | 8.39 | 0.122 |  
| 50 | 0.99971 | 62.409 | 1065.3 | 2.735 | 1.410 | 0.362 | 12.27 | 0.178 |  
| 60 | 0.99902 | 62.366 | 1059.7 | 2.359 | 1.217 | 0.522 | 17.66 | 0.256 |  
| 70 | 0.99798 | 62.301 | 1054.0 | 2.050 | 1.058 | 0.739 | 25.03 | 0.363 |  
| 80 | 0.99662 | 62.216 | 1048.4 | 1.799 | 0.930 | 1.032 | 34.96 | 0.507 |  
| 90 | 0.99497 | 62.113 | 1042.7 | 1.595 | 0.826 | 1.422 | 48.15 | 0.698 |  
| 100 | 0.99306 | 61.994 | 1037.1 | 1.424 | 0.739 | 1.933 | 65.47 | 0.950 |  
| 120 | 0..98856 | 61.713 | 1025.6 | 1.168 | 0.609 | 3.448 | 116.75 | 1.693 |  
| 140 | 0.98321 | 61.379 | 1014.0 | 0.981 | 0.514 | 5.884 | 199.26 | 2.890 |  
| 160 | 0.97714 | 61.000 | 1002.2 | 0.838 | 0.442 | 9.656 | 326.98 | 4.742 |  
| 180 | 0.97041 | 60.580 | 990.2 | 0.726 | 0.386 | 15.295 | 517.95 | 7.512 |  
| 200 | 0.96306 | 60.121 | 977.9 | 0.637 | 0.341 | 23.468 | 794.72 | 11.526 |  
| 212 | 0.95837 | 59.828 | 970.3 | 0.593 | 0.319 | 29.921 | 1013.25 | 14.696 | 
 | 1 To obtain values of viscosity, multiply values shown in Table by 10-5. Source:  Linsley, R. K. et al. (1982). Hydrology for Engineers. 3d. ed., New York: McGraw-Hill.
 | 
 
 
 | TABLE A-3   FACTOR p IN BLANEY-CRIDDLE METHOD.1 |  
| Latitude North
 South
 | Jan
 July
 | Feb
 Aug
 | Mar
 Sep
 | Apr
 Oct
 | May
 Nov
 | Jun
 Dec
 | Jul
 Jan
 | Aug
 Feb
 | Sep
 Mar
 | Oct
 Apr
 | Nov
 May
 | Dec
 Jun
 |  
| 60° | 0.15 | 0.20 | 0.26 | 0.32 | 0.38 | 0.41 | 0.40 | 0.34 | 0.28 | 0.22 | 0.17 | 0.13 |  
| 50° | 0.19 | 0.23 | 0.27 | 0.31 | 0.34 | 0.36 | 0.35 | 0.32 | 0.28 | 0.24 | 0.20 | 0.18 |  
| 40° | 0.22 | 0.24 | 0.27 | 0.30 | 0.32 | 0.34 | 0.33 | 0.31 | 0.28 | 0.25 | 0.22 | 0.21 |  
| 30° | 0.24 | 0.25 | 0.27 | 0.29 | 0.31 | 0.32 | 0.31 | 0.30 | 0.28 | 0.26 | 0.24 | 0.23 |  
| 20° | 0.25 | 0.26 | 0.27 | 0.28 | 0.29 | 0.30 | 0.30 | 0.29 | 0.28 | 0.26 | 0.25 | 0.25 |  
| 10° | 0.26 | 0.27 | 0.27 | 0.28 | 0.28 | 0.29 | 0.29 | 0.28 | 0.28 | 0.27 | 0.26 | 0.26 |  
| 0° | 0.27 | 0.27 | 0.27 | 0.27 | 0.27 | 0.27 | 0.27 | 0.27 | 0.27 | 0.27 | 0.27 | 0.27 | 
 | 1 p = [(mean daily daytime hours for a given month) / (total daytime hours in a year)] × 100 | 
 
 
 | TABLE A-4   FACTOR K IN THORNTHWAITE METHOD.1 |  
| Latitude | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |  
| 60°N | 0.54 | 0.67 | 0.97 | 1.19 | 1.33 | 1.56 | 1.55 | 1.33 | 1.07 | 0.84 | 0.58 | 0.48 |  
| 50°N | 0.71 | 0.84 | 0.98 | 1.14 | 1.28 | 1.36 | 1.33 | 1.21 | 1.06 | 0.90 | 0.76 | 0.68 |  
| 40°N | 0.80 | 0.89 | 0.99 | 1.10 | 1.20 | 1.25 | 1.23 | 1.15 | 1.04 | 0.93 | 0.83 | 0.78 |  
| 30°N | 0.87 | 0.93 | 1.00 | 1.07 | 1.14 | 1.17 | 1.16 | 1.11 | 1.03 | 0.96 | 0.89 | 0.85 |  
| 20°N | 0.92 | 0.96 | 1.00 | 1.05 | 1.09 | 1.11 | 1.10 | 1.07 | 1.02 | 0.98 | 0.93 | 0.91 |  
| 10°N | 0.97 | 0.98 | 1.00 | 1.03 | 1.05 | 1.06 | 1.05 | 1.04 | 1.02 | 0.99 | 0.97 | 0.96 |  
| 0° | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |  
| 10°S | 1.05 | 1.04 | 1.02 | 0.99 | 0.97 | 0.96 | 0.97 | 0.98 | 1.00 | 1.03 | 1.05 | 1.06 |  
| 20°S | 1.10 | 1.07 | 1.02 | 0.98 | 0.93 | 0.91 | 0.92 | 0.96 | 1.00 | 1.05 | 1.09 | 1.11 |  
| 30°S | 1.16 | 1.11 | 1.03 | 0.96 | 0.89 | 0.85 | 0.87 | 0.93 | 1.00 | 1.07 | 1.14 | 1.17 |  
| 40°S | 1.23 | 1.15 | 1.04 | 0.93 | 0.83 | 0.78 | 0.80 | 0.89 | 0.99 | 1.10 | 1.20 | 1.25 |  
| 50°S | 1.33 | 1.19 | 1.05 | 0.89 | 0.75 | 0.68 | 0.70 | 0.82 | 0.97 | 1.13 | 1.27 | 1.36 | 
 | 1 K = Constant to correct PET for latitudes other than 0° (Eq. 2-46). | 
 
 
 | TABLE A-5   VALUES OF F (z) (AREAS UNDER HALF OF THE NORMAL PROBABILITY DENSITY FUNCTION, Eq. 6-11) VERSUS FREQUENCY FACTOR z 
(DOUBLE-ENTRY TABLE). |  
| z | 0.00 | 0.01 | 0.02 | 0.03 | 0.04 | 0.05 | 0.06 | 0.07 | 0.08 | 0.09 |  
| 0.0 | 0.0000 | 0.0040 | 0.0080 | 0.0120 | 0.0159 | 0.0199 | 0.0239 | 0.0279 | 0.0319 | 0.0359 |  
| 0.1 | 0.0398 | 0.0438 | 0.0478 | 0.0517 | 0.0557 | 0.0596 | 0.0636 | 0.0675 | 0.0714 | 0.0753 |  
| 0.2 | 0.0793 | 0.0832 | 0.0871 | 0.0910 | 0.0948 | 0.0987 | 0.1026 | 0.1064 | 0.1103 | 0.1141 |  
| 0.3 | 0.1179 | 0.1217 | 0.1255 | 0.1293 | 0.1331 | 0.1368 | 0.1406 | 0.1443 | 0.1480 | 0.1517 |  
| 0.4 | 0.1554 | 0.1591 | 0.1628 | 0.1664 | 0.1700 | 0.1736 | 0.1772 | 0.1808 | 0.1844 | 0.1879 |  
| 0.5 | 0.1915 | 0.1950 | 0.1985 | 0.2019 | 0.2054 | 0.2088 | 0.2123 | 0.2157 | 0.2190 | 0.2224 |  
| 0.6 | 0.2257 | 0.2291 | 0.2324 | 0.2357 | 0.2389 | 0.2422 | 0.2454 | 0.2486 | 0.2518 | 0.2549 |  
| 0.7 | 0.2580 | 0.2611 | 0.2642 | 0.2673 | 0.2704 | 0.2734 | 0.2764 | 0.2794 | 0.2823 | 0.2852 |  
| 0.8 | 0.2881 | 0.2910 | 0.2939 | 0.2967 | 0.2995 | 0.3023 | 0.3051 | 0.3078 | 0.3106 | 0.3133 |  
| 0.9 | 0.3159 | 0.3186 | 0.3212 | 0.3238 | 0.3264 | 0.3289 | 0.3315 | 0.3340 | 0.3365 | 0.3389 |  
| 1.0 | 0.3413 | 0.3438 | 0.3461 | 0.3485 | 0.3508 | 0.3531 | 0.3554 | 0.3577 | 0.3599 | 0.3621 |  
| 1.1 | 0.3643 | 0.3665 | 0.3686 | 0.3708 | 0.3729 | 0.3749 | 0.3770 | 0.3790 | 0.3810 | 0.3830 |  
| 1.2 | 0.3849 | 0.3869 | 0.3888 | 0.3907 | 0.3925 | 0.3944 | 0.3962 | 0.3980 | 0.3997 | 0.4015 |  
| 1.3 | 0.4032 | 0.4049 | 0.4066 | 0.4082 | 0.4099 | 0.4115 | 0.4131 | 0.4147 | 0.4162 | 0.4177 |  
| 1.4 | 0.4192 | 0.4207 | 0.4222 | 0.4236 | 0.4251 | 0.4265 | 0.4279 | 0.4292 | 0.4306 | 0.4319 |  
| 1.5 | 0.4332 | 0.4345 | 0.4357 | 0.4370 | 0.4382 | 0.4394 | 0.4406 | 0.4418 | 0.4430 | 0.4441 |  
| 1.6 | 0.4452 | 0.4463 | 0.4474 | 0.4485 | 0.4495 | 0.4505 | 0.4515 | 0.4525 | 0.4535 | 0.4545 |  
| 1.7 | 0.4554 | 0.4564 | 0.4573 | 0.4582 | 0.4591 | 0.4599 | 0.4608 | 0.4616 | 0.4625 | 0.4633 |  
| 1.8 | 0.4641 | 0.4649 | 0.4656 | 0.4664 | 0.4671 | 0.4678 | 0.4686 | 0.4693 | 0.4699 | 0.4706 |  
| 1.9 | 0.4713 | 0.4719 | 0.4726 | 0.4732 | 0.4738 | 0.4744 | 0.4750 | 0.4756 | 0.4762 | 0.4767 |  
| 2.0 | 0.4772 | 0.4778 | 0.4783 | 0.4788 | 0.4793 | 0.4798 | 0.4803 | 0.4808 | 0.4812 | 0.4817 |  
| 2.1 | 0.4821 | 0.4826 | 0.4830 | 0.4834 | 0.4838 | 0.4842 | 0.4846 | 0.4850 | 0.4854 | 0.4857 |  
| 2.2 | 0.4861 | 0.4865 | 0.4868 | 0.4871 | 0.4875 | 0.4878 | 0.4881 | 0.4884 | 0.4887 | 0.4890 |  
| 2.3 | 0.4893 | 0.4896 | 0.4898 | 0.4901 | 0.4904 | 0.4906 | 0.4909 | 0.4911 | 0.4913 | 0.4916 |  
| 2.4 | 0.4918 | 0.4920 | 0.4922 | 0.4925 | 0.4927 | 0.4929 | 0.4931 | 0.4932 | 0.4934 | 0.4936 |  
| 2.5 | 0.4938 | 0.4940 | 0.4941 | 0.4943 | 0.4945 | 0.4946 | 0.4948 | 0.4949 | 0.4951 | 0.4952 |  
| 2.6 | 0.4953 | 0.4955 | 0.4956 | 0.4757 | 0.4959 | 0.4960 | 0.4961 | 0.4962 | 0.4963 | 0.4964 |  
| 2.7 | 0.4965 | 0.4966 | 0.4967 | 0.4968 | 0.4969 | 0.4970 | 0.4971 | 0.4972 | 0.4973 | 0.4974 |  
| 2.8 | 0.4974 | 0.4975 | 0.4976 | 0.4977 | 0.4977 | 0.4978 | 0.4979 | 0.4980 | 0.4980 | 0.4981 |  
| 2.9 | 0.4981 | 0.4982 | 0.4983 | 0.4983 | 0.4984 | 0.4984 | 0.4985 | 0.4985 | 0.4986 | 0.4986 |  
| 3.0 | 0.4987 | 0.4987 | 0.4987 | 0.4988 | 0.4988 | 0.4989 | 0.4989 | 0.4989 | 0.4990 | 0.4990 | 
 | Source:  Weatherburn, C. E. (1957). Mathematical Statistics. Cambridge University Press. | 
 
 
 | TABLE A-6   FREQUENCY FACTORS K FOR PEARSON TYPE III DISTRIBUTIONS VERSUS SKEW COEFFICIENT CS AND RETURN PERIOD
T (OR PROBABILITY OF EXCEEDANCE P). |  
| Skew Coeff. Cs
 | Return Period T (y) |  
| 1.05 | 1.11 | 1.25 | 2 | 5 | 10 | 25 | 50 | 100 | 200 |  
|  | Probability of Exceedance (percent) |  
| 95 | 90 | 80 | 50 | 20 | 10 | 4 | 2 | 1 | 0.5 |  
| 3.0 | -0.665 | -0.660 | -0.636 | -0.396 | 0.420 | 1.180 | 2.278 | 3.152 | 4.051 | 4.970 |  
| 2.8 | -0.711 | -0.702 | -0.666 | -0.384 | 0.460 | 1.210 | 2.275 | 3.114 | 3.973 | 4.847 |  
| 2.6 | -0.762 | -0.747 | -0.696 | -0.368 | 0.499 | 1.238 | 2.267 | 3.071 | 3.889 | 4.718 |  
| 2.4 | -0.819 | -0.795 | -0.725 | -0.351 | 0.537 | 1.262 | 2.256 | 3.023 | 3.800 | 4.584 |  
| 2.2 | -0.882 | -0.844 | -0.752 | -0.330 | 0.574 | 1.284 | 2.240 | 2.970 | 3.075 | 4.444 |  
| 2.0 | -0.949 | -0.895 | -0.777 | -0.307 | 0.609 | 1.302 | 2.219 | 2.192 | 3.605 | 4.398 |  
| 1.8 | -1.020 | -0.945 | -0.799 | -0.282 | 0.643 | 1.318 | 2.193 | 2.848 | 3.499 | 4.147 |  
| 1.6 | -1.093 | -0.994 | -0.817 | -0.254 | 0.675 | 1.329 | 2.163 | 2.780 | 3.388 | 3.990 |  
| 1.4 | -1.168 | -1.041 | -0.832 | -0.225 | 0.705 | 1.337 | 2.128 | 2.706 | 3.271 | 3.828 |  
| 1.2 | -1.243 | -1.086 | -0.844 | -0.195 | 0.732 | 1.340 | 2.087 | 2.626 | 3.149 | 3.661 |  
| 1.0 | -1.317 | -1.128 | -0.852 | -0.164 | 0.758 | 1.340 | 2.043 | 2.542 | 3.022 | 3.489 |  
| 0.8 | -1.388 | -1.166 | -0.856 | -0.132 | 0.780 | 1.336 | 1.993 | 2.453 | 2.891 | 3.312 |  
| 0.6 | -1.458 | -1.200 | -0.857 | -0.099 | 0.800 | 1.328 | 1.939 | 2.359 | 2.755 | 3.132 |  
| 0.4 | -1.524 | -1.231 | -0.855 | -0.066 | 0.816 | 1.317 | 1.880 | 2.261 | 2.615 | 2.949 |  
| 0.2 | -1.586 | -1.258 | -0.850 | -0.033 | 0.830 | 1.301 | 1.818 | 2.159 | 2.472 | 2.763 |  
| 0.0 | -1.645 | -1.282 | -0.842 | 0.000 | 0.842 | 1.282 | 1.751 | 2.054 | 2.326 | 2.576 |  
| -0.2 | -1.700 | -1.301 | -0.830 | 0.033 | 0.850 | 1.258 | 1.680 | 1.945 | 2.178 | 2.388 |  
| -0.4 | -1.750 | -1.317 | -0.816 | 0.066 | 0.855 | 1.231 | 1.606 | 1.834 | 2.029 | 2.201 |  
| -0.6 | -1.797 | -1.328 | -0.800 | 0.099 | 0.857 | 1.200 | 1.528 | 1.720 | 1.880 | 2.016 |  
| -0.8 | -1.839 | -1.336 | -0.780 | 0.132 | 0.856 | 1.166 | 1.448 | 1.606 | 1.733 | 1.837 |  
| -1.0 | -1.877 | -1.340 | -0.758 | 0.164 | 0.852 | 1.128 | 1.366 | 1.492 | 1.588 | 1.664 |  
| -1.2 | -1.910 | -1.340 | -0.732 | 0.195 | 0.844 | 1.086 | 1.282 | 1.379 | 1.449 | 1.501 |  
| -1.4 | -1.938 | -1.337 | -0.705 | 0.225 | 0.832 | 1.041 | 1.198 | 1.270 | 1.318 | 1.351 |  
| -1.6 | -1.962 | -1.329 | -0.675 | 0.254 | 0.817 | 0.994 | 1.116 | 1.166 | 1.197 | 1.216 |  
| -1.8 | -1.981 | -1.318 | -0.643 | 0.282 | 0.799 | 0.945 | 1.035 | 1.069 | 1.087 | 1.097 |  
| -2.0 | -1.996 | -1.302 | -0.609 | 0.307 | 0.777 | 0.895 | 0.959 | 0.980 | 0.990 | 0.995 |  
| -2.2 | -2.006 | -1.284 | -0.574 | 0.330 | 0.752 | 0.844 | 0.888 | 0.900 | 0.905 | 0.907 |  
| -2.4 | -2.011 | -1.262 | -0.537 | 0.351 | 0.725 | 0.795 | 0.823 | 0.830 | 0.832 | 0.833 |  
| -2.6 | -2.013 | -1.238 | -0.499 | 0.368 | 0.696 | 0.747 | 0.764 | 0.768 | 0.769 | 0.769 |  
| -2.8 | -2.010 | -1.210 | -0.460 | 0.384 | 0.666 | 0.702 | 0.712 | 0.714 | 0.714 | 0.714 |  
| -3.0 | -2.003 | -1.180 | -0.420 | 0.393 | 0.636 | 0.660 | 0.666 | 0.666 | 0.667 | 0.667 | 
 | Source:  U.S. Interagency Committe on Water Data, Hydrology Subcommitee (1983). "Guidelines
for Determining Flood Flow Frequency," Bulletin No. 17B, issued 1981, revised 1983. | 
 
 
 | TABLE A-7   OUTLIER FREQUENCY FACTORS Kn FOR LOGPEARSON DISTRIBUTIONS. |  
| Record Length
 (y)
 | Kn | Record Length
 (y)
 | Kn | Record Length
 (y)
 | Kn | Record Length
 (y)
 | Kn |  
| 10 | 2.036 | 45 | 2.727 | 80 | 2.940 | 115 | 3.064 |  
| 15 | 2.247 | 50 | 2.768 | 85 | 2.961 | 120 | 3.078 |  
| 20 | 2.385 | 55 | 2.804 | 90 | 2.981 | 125 | 3.092 |  
| 25 | 2.486 | 60 | 2.837 | 95 | 3.000 | 130 | 3.104 |  
| 30 | 2.563 | 65 | 2.866 | 100 | 3.017 | 135 | 3.116 |  
| 35 | 2.628 | 70 | 2.893 | 105 | 3.033 | 140 | 3.129 |  
| 40 | 2.682 | 75 | 2.917 | 110 | 3.049 | 145 | 3.140 | 
 | Source:  U.S. Interagency Committe on Water Data, Hydrology Subcommitee (1983). "Guidelines
for Determining Flood Flow Frequency," Bulletin No. 17B, issued 1981, revised 1983. | 
 
 
 | TABLE A-8   MEAN ȳn AND STANDARD DEVIATION σn OF GUMBEL VARIATE (y) VERSUS RECORD LENGTH n. |  
| n | yn | σn | n | yn | σn | n | yn | σn |  
| 8 | 0.4843 | 0.9043 | 35 | 0.5403 | 1.1285 | 64 | 0.5533 | 1.1793 |  
| 9 | 0.4902 | 0.9288 | 36 | 0.5410 | 1.1313 | 66 | 0.5538 | 1.1814 |  
| 10 | 0.4952 | 0.9497 | 37 | 0.5418 | 1.1339 | 68 | 0.5543 | 1.1834 |  
| 11 | 0.4996 | 0.9676 | 38 | 0.5424 | 1.1363 | 70 | 0.5548 | 1.1854 |  
| 12 | 0.5035 | 0.9833 | 39 | 0.5430 | 1.1388 | 72 | 0.5552 | 1.1873 |  
| 13 | 0.5070 | 0.9972 | 40 | 0.5436 | 1.1413 | 74 | 0.5557 | 1.1890 |  
| 14 | 0.5100 | 1.0095 | 41 | 0.5442 | 1.1436 | 76 | 0.5561 | 1.1906 |  
| 15 | 0.5128 | 1.0206 | 42 | 0.5448 | 1.1458 | 78 | 0.5565 | 1.1923 |  
| 16 | 0.5157 | 1.0316 | 43 | 0.5453 | 1.1480 | 80 | 0.5569 | 1.1938 |  
| 17 | 0.5181 | 1.0411 | 44 | 0.5458 | 1.1499 | 82 | 0.5572 | 1.1953 |  
| 18 | 0.5202 | 1.0493 | 45 | 0.5463 | 1.1519 | 84 | 0.5576 | 1.1967 |  
| 19 | 0.5220 | 1.0566 | 46 | 0.5468 | 1.1538 | 86 | 0.5580 | 1.1980 |  
| 20 | 0.5236 | 1.0628 | 47 | 0.5473 | 1.1557 | 88 | 0.5583 | 1.1994 |  
| 21 | 0.5252 | 1.0696 | 48 | 0.5477 | 1.1574 | 90 | 0.5586 | 1.2007 |  
| 22 | 0.5268 | 1.0754 | 49 | 0.5481 | 1.1590 | 92 | 0.5589 | 1.2020 |  
| 23 | 0.5283 | 1.0811 | 50 | 0.5485 | 1.1607 | 94 | 0.5592 | 1.2032 |  
| 24 | 0.5296 | 1.0864 | 51 | 0.5489 | 1.1623 | 96 | 0.5595 | 1.2044 |  
| 25 | 0.5309 | 1.0915 | 52 | 0.5493 | 1.1638 | 98 | 0.5598 | 1.2055 |  
| 26 | 0.5320 | 1.0961 | 53 | 0.5497 | 1.1653 | 100 | 0.5600 | 1.2065 |  
| 27 | 0.5332 | 1.1004 | 54 | 0.5501 | 1.1667 | 150 | 0.5646 | 1.2253 |  
| 28 | 0.5343 | 1.047 | 55 | 0.5504 | 1.1681 | 200 | 0.5672 | 1.2360 |  
| 29 | 0.5353 | 1.1086 | 56 | 0.5508 | 1.1696 | 250 | 0.5688 | 1.2429 |  
| 30 | 0.5362 | 1.1124 | 57 | 0.5511 | 1.1708 | 300 | 0.5699 | 1.2479 |  
| 31 | 0.5371 | 1.1159 | 58 | 0.5515 | 1.1721 | 400 | 0.5714 | 1.2545 |  
| 32 | 0.5380 | 1.1193 | 59 | 0.5518 | 1.1734 | 500 | 0.5724 | 1.2588 |  
| 33 | 0.5388 | 0.1226 | 60 | 0.5521 | 1.1747 | 750 | 0.5738 | 1.2651 |  
| 34 | 0.5396 | 1.1255 | 62 | 0.5527 | 1.1770 | 1000 | 0.5745 | 1.2685 | 
 | Source:  Gumbel, E. J. (1958). Statistics of Extremes. Irvington, New York: Columbia University Press. | 
 
 
 | TABLE A-9   NRCS 24-HR RAINFALL TABLES (AT HALF-HOUR INCREMENTS). |  
| Time (h)
 | Fraction of 24-h rainfall depth |  
| Type I | Type IA | Type II | Type III |  
| 0.0 | 0.00000 | 0.00000 | 0.00000 | 0.00000 |  
| 0.5 | 0.00871 | 0.01000 | 0.00513 | 0.00500 |  
| 1.0 | 0.01745 | 0.02000 | 0.01050 | 0.01000 |  
| 1.5 | 0.02621 | 0.03500 | 0.01613 | 0.01500 |  
| 2.0 | 0.03500 | 0.05000 | 0.02200 | 0.02000 |  
| 2.5 | 0.04416 | 0.06600 | 0.02813 | 0.02519 |  
| 3.0 | 0.05405 | 0.08200 | 0.03450 | 0.03075 |  
| 3.5 | 0.06466 | 0.09800 | 0.04113 | 0.03669 |  
| 4.0 | 0.07600 | 0.11600 | 0.04800 | 0.04300 |  
| 4.5 | 0.08784 | 0.13500 | 0.05525 | 0.04969 |  
| 5.0 | 0.09995 | 0.15600 | 0.06300 | 0.05675 |  
| 5.5 | 0.11234 | 0.18000 | 0.07125 | 0.06419 |  
| 6.0 | 0.12500 | 0.20600 | 0.0800 | 0.07200 |  
| 6.5 | 0.13915 | 0.23700 | 0.08925 | 0.08063 |  
| 7.0 | 0.15600 | 0.26800 | 0.09900 | 0.09050 |  
| 7.5 | 0.17460 | 0.31000 | 0.10925 | 0.10163 |  
| 8.0 | 0.19400 | 0.42500 | 0.12000 | 0.11400 |  
| 8.5 | 0.21900 | 0.48000 | 0.13225 | 0.12844 |  
| 9.0 | 0.25400 | 0.52000 | 0.14700 | 0.14575 |  
| 9.5 | 0.30300 | 0.55000 | 0.16300 | 0.16594 |  
| 10.0 | 0.51500 | 0.57700 | 0.18100 | 0.18900 |  
| 10.5 | 0.58300 | 0.60100 | 0.20400 | 0.21650 |  
| 11.0 | 0.62300 | 0.62400 | 0.23500 | 0.25000 |  
| 11.5 | 0.65550 | 0.64500 | 0.28300 | 0.29800 |  
| 12.0 | 0.68400 | 0.66400 | 0.66300 | 0.50000 |  
| 12.5 | 0.70925 | 0.68300 | 0.73500 | 0.70200 |  
| 13.0 | 0.73200 | 0.70100 | 0.77200 | 0.75000 |  
| 13.5 | 0.75225 | 0.71900 | 0.79900 | 0.78350 |  
| 14.0 | 0.77000 | 0.73600 | 0.82000 | 0.81100 |  
| 14.5 | 0.78625 | 0.75281 | 0.83763 | 0.83406 |  
| 15.0 | 0.80200 | 0.76924 | 0.85350 | 0.85425 |  
| 15.5 | 0.81725 | 0.78529 | 0.86763 | 0.87156 |  
| 16.0 | 0.83200 | 0.80096 | 0.88000 | 0.88600 |  
| 16.5 | 0.84625 | 0.81625 | 0.89119 | 0.89838 |  
| 17.0 | 0.86000 | 0.83116 | 0.90175 | 0.90950 |  
| 17.5 | 0.87325 | 0.84569 | 0.91169 | 0.91938 |  
| 18.0 | 0.88600 | 0.85984 | 0.92100 | 0.92800 |  
| 18.5 | 0.89825 | 0.87361 | 0.92969 | 0.93581 |  
| 19.0 | 0.91000 | 0.88700 | 0.93775 | 0.94325 |  
| 19.5 | 0.92125 | 0.90001 | 0.94519 | 0.95031 |  
| 20.0 | 0.93200 | 0.91264 | 0.95200 | 0.95700 |  
| 20.5 | 0.94225 | 0.92489 | 0.95844 | 0.96336 |  
| 21.0 | 0.95200 | 0.93676 | 0.96475 | 0.96944 |  
| 21.5 | 0.96125 | 0.94825 | 0.97094 | 0.97523 |  
| 22.0 | 0.97000 | 0.95936 | 0.97700 | 0.98075 |  
| 22.5 | 0.97825 | 0.97009 | 0.98294 | 0.98598 |  
| 23.0 | 0.98600 | 0.98044 | 0.98875 | 0.99094 |  
| 23.5 | 0.99325 | 0.99041 | 0.99444 | 0.99561 |  
| 24.0 | 1.00000 | 1.00000 | 1.00000 | 1.00000 | 
 | Source: Roger G. Cronshey, USDA Natural Resources Conservation Service, Engineering Division, Washington, D.C., June 1988. | 
 
 
 | TABLE A-10   STANDARD NRCS DIMENSIONLESS TEMPORAL RAINFALL DISTRIBUTION FOR EMERGENCY SPILLWAY AND FREEBOARD-POOL DESIGN. |  
| Fraction of storm duration | Fraction of storm depth | Fraction of storm duration | Fraction of storm depth |  
| 0.00 | 0.0000 |  |  |  
| 0.02 | 0.0080 | 0.52 | 0.7240 |  
| 0.04 | 0.0162 | 0.54 | 0.7420 |  
| 0.06 | 0.0246 | 0.56 | 0.7590 |  
| 0.08 | 0.0333 | 0.58 | 0.7750 |  
| 0.10 | 0.0425 | 0.60 | 0.7900 |  
| 0.12 | 0.0524 | 0.62 | 0.8043 |  
| 0.14 | 0.0630 | 0.64 | 0.8180 |  
| 0.16 | 0.0743 | 0.66 | 0.8312 |  
| 0.18 | 0.0863 | 0.68 | 0.8439 |  
| 0.20 | 0.0990 | 0.70 | 0.8561 |  
| 0.22 | 0.1124 | 0.72 | 0.8678 |  
| 0.24 | 0.1265 | 0.74 | 0.8790 |  
| 0.26 | 0.1420 | 0.76 | 0.8898 |  
| 0.28 | 0.1595 | 0.78 | 0.9002 |  
| 0.30 | 0.1800 | 0.80 | 0.9103 |  
| 0.32 | 0.2050 | 0.82 | 0.9201 |  
| 0.34 | 0.2550 | 0.84 | 0.9297 |  
| 0.36 | 0.3450 | 0.86 | 0.9391 |  
| 0.38 | 0.4370 | 0.88 | 0.9483 |  
| 0.40 | 0.5300 | 0.90 | 0.9573 |  
| 0.42 | 0.6030 | 0.92 | 0.9661 |  
| 0.44 | 0.6330 | 0.94 | 0.9747 |  
| 0.46 | 0.6600 | 0.96 | 0.9832 |  
| 0.48 | 0.6840 | 0.98 | 0.9916 |  
| 0.50 | 0.7050 | 1.00 | 1.0000 | 
 | Source: USDA Natural Resources Conservation Service. (1983). "Computer Program for Project Formulation: Hydrology,"
Tecnical Release No. 20  (TR-20), Engineering Division, Washington, D.C., May. | 
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