ABSTRACT
Increasing urbanisation and climate change are leading to problems in the operation of storm and combined sewer networks, and to a smaller extent, in sanitary sewers. As a result, it requires reduction of surface runoff through appropriate selection of pavement, nature base solution facilities (infiltration ditches, rain gardens, water barrels, etc.) and control of wastewater flow in the sewer network. The last option can be implemented through the construction of detention basins, which lead to the reduction of the maximum flow and delay the outflow. In combined sewer and sanitary sewer networks, detention tanks are designed to protect wastewater treatment plants from rapid inflow (increased inflow, but lower concentrations). This chapter discusses the role of reservoirs in sewerage networks, as well as the principles of their design. Water volume balance equations and methods of its solution, based on simplifying complexes, numerical methods and graphical-analytical methods, which were obtained based on calculations with mechanistic models (e.g., SWMM), are given. Novel analytical-graphical methods are presented, in which the shape parameters of the hydrographs are related to the designed outflow from the reservoir and the cross-section of the accumulation chamber. In response to the increasing dynamics of rainfall in recent years, innovative methods were proposed to take into account the uncertainty of the shape of the hydrograph of the inflow to the reservoir, and the theoretical basis of reservoir reliability models in the context of rainfall occurring one after another in a short time interval was given. The role of uncertainty in mechanistic models in the design of overflow detention reservoirs is highlighted, and a method for determining the authoritative rainfall duration is proposed for this case.
