ABSTRACT
This chapter discusses various types of surfaces that can be distinguished in regional water systems and the associated runoff processes that are of importance to regional water-system control. The subsystems of an urban area can incorporate rapid and slow runoff processes, such as rapid runoff via sewer systems and slow runoff via the permeable subsurface of green belts. Wastewater from homes and industry is discharged as sewage water into sewer systems. A small, and fortunately continuously decreasing amount of waste water is discharged directly onto surface waters. The soil moisture content and the water pressure in the soil determine whether plant roots are able to take up water from the soil. Field capacity is the equilibrium situation in which the maximum quantity of water is contained in the unsaturated zone by capillary forces, notwithstanding the force of gravity. The sluice structure consists of one or more culverts, each of which can be closed off by a sliding gate.
