Lecture 9 - Urban Drainage Systems

Question 1

What 2 components does a typical urban drainage system consist of?

Answer 1

minor system and major system

Question 2

What is a minor system?

Answer 2

usually consists of inlets (catchbasins, grates) that collect surface runoff and direct it into pipes, typically designed to handle peak runoff rates from 2 to 10 year return period events

Question 3

What is a major system?

Answer 3

surface drainage pathways that can transmit peak runoff rates from extreme events, such as 100 year return period event, examples include channels and curb gutters

Question 4

What is Directly Connect Impervious Area (DCIA)?

Answer 4

paved/impermeable surfaces that drain directly to a stormwater inlet, in some situations necessary to analyze this area seperately from entire drainage area for sizing drainage structures, DCIA respons faster than whole catchment so shorter and more intense rainfall causes DCIA to reach equilibrium