Kan. Admin. Regs. § 5-40-31
(a) If the time of concentration is six hours or less, a duration of six hours shall be used for all design storms. The appropriate six-hour storm depth, in inches, shall be selected from the following table.
| County | Probability of occurrence in any year | |||||
| 50% | 20% | 4% | 2% | 1% | PMP | |
| Allen | 2.7 | 3.5 | 4.8 | 5.4 | 6.1 | 28.0 |
| Anderson | 2.7 | 3.5 | 4.8 | 5.3 | 6.0 | 27.8 |
| Atchison | 2.6 | 3.4 | 4.5 | 5.1 | 5.7 | 27.2 |
| Barber | 2.4 | 3.2 | 4.4 | 5.0 | 5.7 | 27.3 |
| Barton | 2.3 | 3.0 | 4.1 | 4.8 | 5.3 | 26.6 |
| Bourbon | 2.7 | 3.5 | 4.8 | 5.4 | 6.0 | 28.1 |
| Brown | 2.5 | 3.2 | 4.4 | 5.0 | 5.6 | 27.0 |
| Butler | 2.6 | 3.4 | 4.7 | 5.3 | 6.0 | 27.7 |
| Chase | 2.6 | 3.4 | 4.6 | 5.2 | 5.9 | 27.5 |
| Chautauqua | 2.7 | 3.5 | 4.9 | 5.5 | 6.2 | 28.3 |
| Cherokee | 2.8 | 3.6 | 5.0 | 5.5 | 6.2 | 28.5 |
| Cheyenne | 1.8 | 2.4 | 3.4 | 3.8 | 4.3 | 24.7 |
| Clark | 2.2 | 3.0 | 4.1 | 4.7 | 5.3 | 26.7 |
| Clay | 2.5 | 3.2 | 4.3 | 5.0 | 5.5 | 26.8 |
| Cloud | 2.4 | 3.1 | 4.2 | 4.8 | 5.4 | 26.6 |
| Coffey | 2.7 | 3.5 | 4.7 | 5.3 | 6.0 | 27.8 |
| Comanche | 2.3 | 3.1 | 4.2 | 4.9 | 5.5 | 27.0 |
| Cowley | 2.6 | 3.4 | 4.8 | 5.4 | 6.1 | 28.0 |
| Crawford | 2.8 | 3.6 | 4.9 | 5.4 | 6.1 | 28.3 |
| Decatur | 1.9 | 2.6 | 3.6 | 4.2 | 4.6 | 25.3 |
| Dickinson | 2.5 | 3.2 | 4.4 | 5.1 | 5.6 | 27.1 |
| Doniphan | 2.5 | 3.2 | 4.5 | 5.0 | 5.6 | 27.0 |
| Douglas | 2.6 | 3.4 | 4.6 | 5.2 | 5.8 | 27.5 |
| Edwards | 2.2 | 2.9 | 4.1 | 4.7 | 5.3 | 26.7 |
| Elk | 2.7 | 3.5 | 4.8 | 5.4 | 6.1 | 28.1 |
| Ellis | 2.1 | 2.9 | 3.9 | 4.6 | 5.0 | 26.2 |
| Ellsworth | 2.3 | 3.1 | 4.2 | 4.9 | 5.4 | 26.7 |
| Finney | 2.0 | 2.6 | 3.8 | 4.3 | 4.8 | 26.8 |
| Ford | 2.1 | 2.8 | 4.0 | 4.6 | 5.1 | 26.4 |
| Franklin | 2.7 | 3.5 | 4.7 | 5.2 | 5.9 | 25.8 |
| Geary | 2.5 | 3.2 | 4.4 | 5.1 | 5.7 | 27.1 |
| Gove | 2.0 | 2.6 | 3.7 | 4.3 | 4.7 | 25.7 |
| Graham | 2.0 | 2.7 | 3.8 | 4.4 | 4.8 | 25.8 |
| Grant | 1.9 | 2.6 | 3.7 | 4.2 | 4.7 | 25.6 |
| Gray | 2.0 | 2.7 | 3.9 | 4.4 | 4.9 | 26.1 |
| Greeley | 1.8 | 2.5 | 3.4 | 3.9 | 4.4 | 25.0 |
| Greenwood | 2.7 | 3.5 | 4.8 | 5.3 | 6.1 | 27.8 |
| Hamilton | 1.8 | 2.5 | 3.5 | 4.0 | 4.5 | 25.2 |
| Harper | 2.5 | 3.3 | 4.5 | 5.2 | 5.9 | 27.5 |
| Harvey | 2.5 | 3.3 | 4.5 | 5.1 | 5.8 | 27.4 |
| Haskell | 2.0 | 2.7 | 3.8 | 4.3 | 4.8 | 25.9 |
| Hodgeman | 2.1 | 2.8 | 3.9 | 4.5 | 5.0 | 26.3 |
| Jackson | 2.6 | 3.4 | 4.5 | 5.1 | 5.7 | 27.2 |
| Jefferson | 2.6 | 3.4 | 4.6 | 5.1 | 5.8 | 27.3 |
| Jewell | 2.3 | 2.9 | 4.0 | 4.7 | 5.1 | 26.3 |
| Johnson | 2.6 | 3.4 | 4.6 | 5.2 | 5.8 | 27.5 |
| Kearny | 1.9 | 2.6 | 3.6 | 4.1 | 4.6 | 25.5 |
| Kingman | 2.4 | 3.2 | 4.4 | 5.1 | 5.7 | 27.3 |
| Kiowa | 2.2 | 2.9 | 4.2 | 4.8 | 5.4 | 26.7 |
| Labette | 2.8 | 3.6 | 5.0 | 5.5 | 6.2 | 28.4 |
| Lane | 2.0 | 2.7 | 3.7 | 4.3 | 4.8 | 25.8 |
| Leavenworth | 2.6 | 3.4 | 4.6 | 5.1 | 5.8 | 27.4 |
| Lincoln | 2.3 | 3.0 | 4.2 | 4.8 | 5.3 | 26.6 |
| Linn | 2.7 | 3.5 | 4.8 | 5.3 | 6.0 | 27.9 |
| Logan | 1.9 | 2.5 | 3.6 | 4.1 | 4.6 | 25.3 |
| Lyon | 2.6 | 3.4 | 4.6 | 5.2 | 6.0 | 27.5 |
| Marion | 2.5 | 3.3 | 4.5 | 5.2 | 5.8 | 27.3 |
| Marshall | 2.5 | 3.2 | 4.3 | 4.9 | 5.5 | 26.8 |
| McPherson | 2.5 | 3.2 | 4.4 | 5.1 | 5.7 | 27.1 |
| Meade | 2.1 | 2.8 | 4.0 | 4.6 | 5.1 | 26.3 |
| Miami | 2.7 | 3.5 | 4.7 | 5.2 | 5.9 | 27.7 |
| Mitchell | 2.3 | 3.0 | 4.1 | 4.7 | 5.2 | 26.4 |
| Montgomery | 2.8 | 3.5 | 5.0 | 5.5 | 6.2 | 28.3 |
| Morris | 2.6 | 3.4 | 4.5 | 5.1 | 5.8 | 27.3 |
| Morton | 1.9 | 2.5 | 3.6 | 4.1 | 4.6 | 25.4 |
| Nemaha | 2.5 | 3.2 | 4.4 | 5.0 | 5.6 | 26.9 |
| Neosho | 2.7 | 3.5 | 4.9 | 5.5 | 6.1 | 28.2 |
| Ness | 2.1 | 2.8 | 3.9 | 4.5 | 4.9 | 26.1 |
| Norton | 2.0 | 2.6 | 3.7 | 4.3 | 4.7 | 25.6 |
| Osage | 2.6 | 3.4 | 4.6 | 5.2 | 5.9 | 27.5 |
| Osborne | 2.2 | 2.9 | 4.0 | 4.6 | 5.1 | 26.2 |
| Ottawa | 2.4 | 3.1 | 4.3 | 4.9 | 5.4 | 26.8 |
| Pawnee | 2.2 | 2.9 | 4.1 | 4.7 | 5.2 | 26.6 |
| Phillips | 2.1 | 2.8 | 3.8 | 4.4 | 4.9 | 25.8 |
| Pottawatomie | 2.5 | 3.2 | 4.4 | 5.0 | 5.6 | 27.0 |
| Pratt | 2.3 | 3.1 | 4.3 | 4.9 | 5.5 | 27.0 |
| Rawlins | 1.9 | 2.5 | 3.5 | 4.0 | 4.5 | 25.0 |
| Reno | 2.4 | 3.2 | 4.4 | 5.0 | 5.7 | 27.2 |
| Republic | 2.3 | 3.0 | 4.1 | 4.8 | 5.3 | 26.4 |
| Rice | 2.4 | 3.1 | 4.3 | 4.9 | 5.5 | 26.9 |
| Riley | 2.5 | 3.2 | 4.4 | 5.0 | 5.6 | 27.0 |
| Rooks | 2.1 | 2.8 | 3.9 | 4.5 | 4.9 | 26.0 |
| Rush | 2.2 | 2.9 | 4.0 | 4.6 | 5.1 | 26.4 |
| Russell | 2.2 | 2.9 | 4.1 | 4.7 | 5.2 | 26.5 |
| Saline | 2.4 | 3.1 | 4.3 | 5.0 | 5.5 | 26.9 |
| Scott | 1.9 | 2.6 | 3.6 | 4.2 | 4.7 | 25.5 |
| Sedgwick | 2.5 | 3.3 | 4.6 | 5.2 | 5.9 | 27.5 |
| Seward | 2.0 | 2.7 | 3.8 | 4.4 | 4.9 | 26.0 |
| Shawnee | 2.6 | 3.4 | 4.6 | 5.1 | 5.8 | 27.4 |
| Sheridan | 2.0 | 2.6 | 3.7 | 4.2 | 4.7 | 25.5 |
| Sherman | 1.8 | 2.4 | 3.4 | 3.9 | 4.4 | 24.8 |
| Smith | 2.2 | 2.9 | 3.9 | 4.6 | 5.0 | 26.1 |
| Stafford | 2.3 | 3.0 | 4.2 | 4.9 | 5.4 | 26.9 |
| Stanton | 1.9 | 2.5 | 3.6 | 4.1 | 4.5 | 25.3 |
| Stevens | 1.9 | 2.6 | 3.7 | 4.3 | 4.7 | 25.8 |
| Sumner | 2.6 | 3.4 | 4.7 | 5.3 | 6.0 | 27.8 |
| Thomas | 1.9 | 2.5 | 3.5 | 4.1 | 4.5 | 25.2 |
| Trego | 2.0 | 2.7 | 3.8 | 4.4 | 4.9 | 25.9 |
| Wabaunsee | 2.6 | 3.4 | 4.5 | 5.1 | 5.8 | 27.3 |
| Wallace | 1.8 | 2.4 | 3.4 | 3.9 | 4.4 | 24.9 |
| Washington | 2.4 | 3.1 | 4.2 | 4.9 | 5.4 | 26.6 |
| Wichita | 1.9 | 2.5 | 3.5 | 4.1 | 4.5 | 25.3 |
| Wilson | 2.7 | 3.5 | 4.9 | 5.4 | 6.1 | 28.1 |
| Woodson | 2.7 | 3.5 | 4.8 | 5.4 | 6.1 | 28.0 |
| Wyandotte | 2.6 | 3.4 | 4.6 | 5.1 | 5.8 | 27.4 |
(b) If the time of concentration of the watershed, or any subwatershed being used to develop the inflow hydrograph, is more than six hours, the ratio for the time equal to or greater than the computed time of concentration shall be selected from the following table. Linear interpolation shall be acceptable. That ratio shall be multiplied by the depth of the six-hour rainfall in the table in subsection (a). The resulting depth is the design duration rainfall depth.
| Relative increase in rainfall amount for storm durations over six hours | ||
| Time (hours) | 100-year ratio | PMP ratio |
| 6 | 1.000 | 1.000 |
| 6.5 | 1.019 | 1.013 |
| 7 | 1.035 | 1.025 |
| 7.5 | 1.051 | 1.037 |
| 8 | 1.066 | 1.048 |
| 8.5 | 1.081 | 1.058 |
| 9 | 1.094 | 1.068 |
| 9.5 | 1.108 | 1.078 |
| 10 | 1.120 | 1.087 |
| 10.5 | 1.132 | 1.096 |
| 11 | 1.144 | 1.104 |
| 11.5 | 1.155 | 1.112 |
| 12 | 1.166 | 1.120 |
| 13 | 1.187 | 1.134 |
| 14 | 1.207 | 1.148 |
| 15 | 1.225 | 1.161 |
| 16 | 1.243 | 1.173 |
| 17 | 1.259 | 1.185 |
| 18 | 1.275 | 1.196 |
| 20 | 1.305 | 1.217 |
| 22 | 1.333 | 1.236 |
| 24 | 1.359 | 1.254 |
| Drainage area | Reduction ratio | ||
| (sq. mi.) | Zone 1 | Zone 2 | Zone 3 |
| 10 | 1.00 | 1.00 | 1.00 |
| 12 | 0.99 | 0.99 | 0.98 |
| 15 | 0.97 | 0.95 | 0.93 |
| 17 | 0.96 | 0.94 | 0.91 |
| 20 | 0.94 | 0.91 | 0.88 |
| 22 | 0.93 | 0.90 | 0.86 |
| 25 | 0.92 | 0.88 | 0.83 |
| 27 | 0.92 | 0.87 | 0.82 |
| 30 | 0.91 | 0.86 | 0.80 |
| 35 | 0.90 | 0.84 | 0.77 |
| 40 | 0.88 | 0.82 | 0.75 |
| 45 | 0.87 | 0.80 | 0.72 |
| 50 | 0.86 | 0.78 | 0.70 |
| 60 | 0.84 | 0.75 | 0.65 |
| 70 | 0.82 | 0.72 | 0.62 |
| 80 | 0.80 | 0.70 | 0.59 |
| 90 | 0.79 | 0.68 | 0.57 |
| 100 | 0.78 | 0.67 | 0.55 |
Zone 1, zone 2, and zone 3 shall have the meanings specified in K.A.R. 5-40-1 under the definition of a "stream."
(Authorized by and implementing K.S.A. 2006 Supp. 82a-303a; effective May 18, 2007.)