Learning Objectives:

• Recognize the primary purpose of stormwater detention, which is to manage excessive stormwater runoff and protect the environment and public safety.
• Differentiate between stormwater detention and retention. Detention temporarily holds and releases stormwater, while retention permanently stores it for purposes such as groundwater recharge.
• Learn how to design stormwater detention basins, including considerations for sizing, location, depth, and outlet structures.

Solved Example: 12121

What is the primary purpose of stormwater detention in a civil engineering context?

A. To increase groundwater recharge

B. To treat stormwater for contaminants

C. To temporarily store and slowly release stormwater

D. To prevent stormwater runoff entirely

Correct Answer: C

Solved Example: 2222

Which of the following factors affects the design of a stormwater detention basin?

A. Erosion control methods

B. Groundwater quality testing

C. Hydrologic characteristics of the watershed

D. Stormwater conveyance system capacity

Correct Answer: C

Learning Objectives:

• Understand the fundamental principles of the hydrologic cycle, including precipitation, evaporation, infiltration, and runoff.
• Analyze rainfall data to determine rainfall intensity-duration-frequency (IDF) relationships for stormwater design.
• Interpret hydrographs and hydrograph components to assess stormwater runoff behavior.
• Apply appropriate runoff models (e.g., Rational Method, SCS Curve Number Method) to estimate runoff volumes and peak flow rates for different design scenarios.
• Design stormwater detention and retention basins to control peak flows, attenuate runoff, and manage stormwater quality.
• Design stormwater pipe networks, including pipe sizing, hydraulic analysis, and selection of appropriate materials.
• Apply principles of open channel flow, including the Manning's equation, to calculate flow rates, velocities, and channel dimensions for stormwater conveyance.
• Identify and design stormwater BMPs, such as infiltration basins, bioretention systems, green roofs, and permeable pavements, to promote sustainable stormwater management.
• Understand floodplain mapping, floodplain regulations, and flood hazard mitigation techniques to reduce the risk of flooding.
• Learn methods for controlling and treating stormwater runoff to address water quality concerns, including pollutant removal and erosion control.

Stormwater routing is a critical aspect of civil engineering that deals with the management and control of rainwater runoff in urban and rural areas. Here are some general concepts related to stormwater routing:

1. Hydrologic Cycle: Understand the various components of the hydrologic cycle, including precipitation, runoff, infiltration, and evaporation, and their role in stormwater management.
2. Rainfall Analysis: Learn how to analyze rainfall data, including intensity-duration-frequency (IDF) curves, to estimate design storm events for engineering purposes.
3. Hydrographs: Study hydrographs, which represent the time-dependent variation of stormwater runoff. Learn to create and interpret hydrographs using rainfall data.
4. Runoff Models: Understand different runoff models, such as the Rational Method and the Soil Conservation Service (SCS) curve number method, for estimating runoff volumes and peak flows.
5. Detention and Retention Basins: Explore the design and function of stormwater detention and retention basins, which store and slow down stormwater runoff to reduce peak flows and prevent flooding.
6. Pipe Networks: Learn about stormwater pipe networks and how to design them to efficiently transport runoff from streets and urban areas to appropriate discharge points.
7. Open Channel Flow: Understand the principles of open channel flow, including the Manning's equation, to calculate flow rates and velocities in natural and artificial channels.
8. Stormwater Management Practices: Familiarize yourself with best management practices (BMPs) for stormwater management, including green infrastructure, permeable pavements, and bio-retention systems.
9. Floodplain Management: Learn about floodplain mapping and management to reduce the risk of flooding in urban and rural areas.
10. Regulations and Standards: Be aware of relevant regulations, codes, and standards related to stormwater management, such as local stormwater ordinances and the Clean Water Act.
11. Environmental Considerations: Consider the environmental impacts of stormwater runoff, including pollutant removal and protection of natural habitats.
12. Sustainability: Explore sustainable stormwater management practices that promote water conservation and minimize the impact on ecosystems.

Solved Example: 9358-01

To estimate the magnitude of a flood peak (Q_p) by the formula \[{Q_P} = \dfrac{{124A}}{{\sqrt {A + 10.4}}}\], where A = catchment area in km$^2$. This formula is termed as:

A. Dicken's formula

B. Inglis formula

C. Ryves formula

D. Rational formula

Correct Answer: B

Solved Example: 9358-02

The extent to which the inflow hydrograph gets modified due to the reservoir storage can be computed by a process known as:

A. River routing

B. Channel routing

C. S hydrograph

D. Flood routing or reservoir routing

Correct Answer: D

Learning Objectives:

• Recognize the significance of managing stormwater quality to protect aquatic ecosystems, safeguard public health, and comply with regulatory requirements.
• Understand the various sources of stormwater pollution, including industrial discharges, construction site runoff, transportation-related contaminants (such as oil and heavy metals), and residential pollutants (such as fertilizers and pesticides).
• Familiarize yourself with the characteristics of common stormwater pollutants, including sediments, nutrients (nitrogen and phosphorus), bacteria, chemicals, heavy metals, and oils and grease.