Method of Calculation of the Maximum Rainwater Flow in Central Latvia

Author: Sergejs Jakovlevs

Type of publication: Conference proceeding

Altogether, the assumption (hypothesis) that the maximum intensity of rain (imax) is revealed within the first 20÷30 minutes proved to be false (Jakovlevs S., Gusta S. & Tilgalis E., 2017). The actual rain intensity (5÷6÷7 mm . min-1) for certain 3-hour periods is 30 to 115 minutes, and it can occur with a 3÷4÷5 multiple repetitions of the maximum intensity peaks, see Figure 1 (1; 2; 3; 4). The period of rain, where the maximum intensity peaks of precipitation can recur several times, usually leads to the flooding of the territories. The author believes that the existing method of calculation given in LBN 223-15, SNiP 2.04.03-85 and TPC 45-4.01-57-2012 (02250) and based on the data of maximum intensity of a 20-minute rain period provide no longer a practical and effective result, which is proved by regular floods in the recent years. It is proposed to apply the formula that takes into account the maximum precipitation amount within a 3-hour rain period. Today, the Latvian Environment, Geology and Meteorology Centre measures precipitations with a multiplicity of 3 hours.