Hydraulic calculation of mechanically arranged drainage lines with vertical bends

The mechanical opening of drainage trenches cannot ensure constant drain line slopes. Therefore vertical bends in the pipelines are being formed. Air accumulates in these bends. Consequently the conductivity of collector drains reduces. The air is carried out by the water flow. However significant air volumes are not removed until the beginning of the dry season. Particularly unfavourable conditions for drainage operation are created when the slope of the collector drains is undulating. For the hydraulic calculation of drain parameters, an estimation of air volumes accumulated in drainage systems at the control time has to be performed. The calculation of the air moving process is necessary during the entire snow melting period. The special hydraulic calculation method is needed for this purpose. The creation and applying of this method is described in the article.