Question

5.Discuss the effects of global climate change or local climate change on stormwater management and hydrologic design? As a practicing engineering, discuss steps to ehslts fion stucie tin ats

Answer 1

• Changes in global climate such as increasing temperatures, changing precipitation patterns and also affecting water resources, experience periods of drought and water shortage, more frequent heavy precipitation events as well as experience of alternating drought and heavy precipitation events.
• Stormwater runoff from artificial structures such as pavements which includes roads, side walk, drive way as well as parking lot and roofs is increasingly eye catching due to effects like recurrence of floods, worsening of water quality in receiving waters and risk to the downstream ecosystems.
• Management of stormwater condition is an important part of strategies to improve the environmental status of natural waters. The practice of hydrologic design of stormwater facilities in the current periods uses the precipitation depths which is calculated from the investigation of historical data for a standard return period.
• These design from the analysis of historical data does not considerate the effects of climate change on future meteorological conditions, hence the assumption may be subjected to errors i.e Hydrologic data is no longer static over time, i.e. there is no “finish-line”

• The steps to incorporate climate change results from studies into engineering design aspects are as follows:

• Adaptive option includes:
• Design using historic design flow and accept a gradual reduce in the level of service.
• No need of adjustment to the design flows to consider climate change
• Approach adequate where the incurrence of minor damage associated with flooding is acceptable
• Known as Ostrich Approach

• Design the infrastructure for shorter service lives and retrofit when condition requires.
• Design for flows expected in the short period
• Use shorter design lives which can adjusted when uncertainty prevails
• Known as Mulligan Approach

• Design using future design flows i.e adjust the historic design flow
• Accomodate historic climate record to anticipate future conditions
• Hydraulic capacity appropriate for the end of service life
• Known as Chicken Little Approach