ABSTRACT
In a natural/rural catchment, stormwater drainage is not an important issue, as nature has its own way of draining stormwater from catchment surfaces to natural watercourses/creeks through some small natural drains. The analysis of urban stormwater is complicated as it deals with different types of flows, such as impervious surface flow, natural surface flow, piped flow and flow along the street kerb. Rapid urbanisation increased the impervious surface and consequently decreased the subsurface infiltration, which has resulted in an increased risk of urban flooding in many urban areas. In an urban drainage system, pits are positioned in strategic locations in order to maximise the entry of overland flow into the pipe system. In urban development, stormwater drainage pipes are underground and often run along the street, and sometime across the house boundaries.
