ABSTRACT
Urban drainage systems contain a wide range of different hydraulic features. This chapter explores these features in detail. It discusses flow controls of various types, and deals with weirs. The chapter explains sewer drops and inverted siphons. It also discusses gully spacing methods and culvert design. Flow controls can be used to limit the inflow to, or outflow from, elements in an urban drainage system. The simplest way of controlling inflow to a pipe is by an orifice plate. This forces the flow to pass through an area less than that of the pipe. In a similar way to an orifice plate or penstock, a vortex regulator constricts flow, usually with the purpose of exploiting a storage volume; the magnitude of the flow rate passing through the device depends on the upstream water depth. A flap valve is a hinged plate at a pipe outlet that restricts flow to one direction only.
