This document discusses approaches to urban drainage and management of runoff quantity and quality. It explains that traditional drainage methods focus on end-of-pipe solutions and canalization, which can increase surface flows and flood peaks. Sustainable drainage systems (SUDS) methods maintain natural conditions using storage and infiltration to control runoff. Common design approaches include empirical peak runoff methods, hydrologic simulation models, and the Rational Method equation. Models simulate the effects of development on stormwater systems. Managing runoff quality is also important as urbanization increases impervious surfaces and runoff into streams.

1. BASIC APPOARCH TO URBAN
DRAINAGE-RUNOFF QUANTITY
AND QUALITY

2. What is Urban Drainage?
 The city is made up of several interconnected nets and services that
work together and interact with each other. The relation between
water and city is very close, the urban layout defines new patterns for
natural drainage system and changes the hydrological cycle
increasing the peak discharges.
 since the industrial ages urban drainage system were designed to
face sanitation problems and adequate the system to the exceeding
runoff. Every flood project tend to focus on improving discharge
capacity.
 Vegetation removal and sealing of large surface areas produce more
runoff and the designed streets define the new superficial flow paths.

4. Basic Approaches
 Design of storm drainage infrastructure for urban areas involve the determination of the
size of the storm drainage system components required to convey a design flow; while
the planning for storm drainage infrastructure focuses primarily on the allocation of
land and easements to accommodate this infrastructure, and controlling or limiting the
interaction between drainage infrastructures and surrounding development.
 The magnitude of this design flow is selected based on the level of service that a
specific piece of drainage infrastructure should provide (i.e. what are the consequences
of flooding and how often is flooding acceptable?), and is often defined in terms of the
frequency of reoccurrence, either as a probability of flow exceedance or a recurrence
interval between events of similar magnitude.
 Once the level of service is selected and the appropriate design frequency is chosen,
hydro technical design involves the use of accepted design methodologies, considering
hydrologic input and appropriate design parameters.

5. Traditional method
Tends to focus on end of pipe solution with high imperviousness
and canalization are able to increase surface flows and flood peaks.

6. SUDS method
Tends to focus on maintaining natural conditions and
using storage and infiltration measures.

7. What is SUDS?
Are alternative way of urban drainage to collect, clean, store
and release stormwater.
They are designed to minimize the amount of rainwater on
urban land to enter canalization.
They attenuate the velocity of runoff and slow down its
eventual discharge.
Provide habitats for wildlife in urban areas.

10. Runoff Quantity and
Quality

11. Runoff Quantity and Quality
 Water can take many routes as it falls from the sky in the form of rain
and other precipitation, and finally seeps into the ground. You can
figure out how much water can direct itself through these paths of
sinking through soil or other material into the earth after heavy
amounts of rain. The surface runoff of water is one way of
determining how much water an event of precipitation produces.
 More nuanced, complicated equations take into account factors such
as variations in how much rain a storm creates over time. One
method, known as the Rational Method uses the Rational
Equation C = Q/(iA) for runoff coefficient C, peak runoff rate Q,
rainfall intensity i (in in/hour) and size of the area A (usually in acres).

12. Accepted methodologies for the calculation of design flow magnitudes
consist of either empirical peak runoff methods, hydrologic simulation
models, or statistical methods based on the analysis of hydrometric
records.
As the applicability of statistical methods is generally limited to the
calculation of design flow magnitudes in natural watercourses, the
design methods that are commonly used in urban drainage design
generally consist of empirical peak runoff methods, and hydrologic
simulation models.
Both empirical peak runoff methods and hydrologic simulation models
are based on parameters that describe the land use upstream of the
infrastructure being designed, as well as values of rainfall and
snowmelt that are appropriate for the local conditions.

13. Rational Method
Q= C i A
Where: Q=Peak Runoff Rate
C=Runoff Coefficient
i=Rainfall Intensity
A=Area

14. Hydraulic Simulation Models
 Simulate the effects of land use change and urbanization on your storm water
management system. Use interface with integrated height models, background
maps and other data sources for designing optimal storm water management
systems.
 In simpler terms it is the use of software's to design and test magnitudes and
peaks of runoffs and flood simulations with the aid of parameters that describe
the land use upstream of the infrastructure being designed, as well as values of
rainfall and snowmelt that are appropriate for the local conditions.

15. Quality
 In natural environment portion of rainfall is absorbed into the
soils and slowly discharged to streams. Flooding is less significant
due to less amount of runoff into the streams.
 As watersheds are urbanised with impervious surfaces, resulting in
increase of runoff. The high amount of discharge to the streams
result in flooding.