Computation method of the drainage retention capacity of soil layers with a subsurface pipe drainage system

Methodological procedure for determining the drainage retention capacity (DRC) of surface layers under conditions of unsteady-state groundwater flow was demonstrated. DRC of the drainage system can be defined as a groundwater reservoir situated between the soil surface and the intermediate position of a parabola shaped water table above the drain level. Computation of DRC is based on analytical approximation of the subsurface total drainage discharge in unsteady-state groundwater conditions. DRC formula can serve as a simple tool for immediate estimation that requires only minimum amount of basic information (drainage design parameters, soil hydrology data). DRC is an important phenomenon of drainage policy, an inseparable part of drainage processes, which can mitigate negative impact of climate dynamics. A properly applied drainage policy, with the possibility of manipulating the retention capacities in the soil layers, can significantly improve soil and environmental protection. In agriculture, DRC extended by a drainage system can mitigate the negative effects of hydrological extremes such as floods and droughts.