It flooded in Singapore
Flood: Principal types and causes
· Riverine:
Slow kinds: Runoff from sustained rainfall or rapid snow melt exceeding the capacity of a river's channel. Causes include heavy rains from monsoons, hurricanes etc. Unexpected drainage obstructions such as landslides,ice, or debris can cause slow flooding upstream of the obstruction.
Fast kinds: include flash floods resulting from convective precipitation (intense thunderstorms) or sudden release from an upstream impoundment created behind a dam,landslide, or glacier.
· Estuarine: Commonly caused by a combination of sea tidal surges caused by storm-force winds. E.g. cyclone
· Coastal: Caused by severe sea storms, or as a result of another hazard (e.g.tsunami or hurricane).
· Catastrophic: Caused by a significant and unexpected event e.g. dam breakage, or as a result of another hazard (e.g. earthquake or volcanic eruption).
· Muddy: A muddy flood is generated by run off on crop land.
· Other: Floods can occur if water accumulates across an impermeable surface and cannot rapidly dissipate OR a series of storms moving over the same area OR Dam-building beavers can flood low-lying urban and rural areas, often causing significant damage
· Singapore kind of flooding: Riverine and Others
The Mechanics of Flooding – why it floods
- Extremely heavy rainfalls (the heavy rainfalls were approximately more than 60 per cent of the average monthly rainfall for June)
- The amount of rain exceeded the capacity that the drains in
Orchard Road were designed for. - A second intense rainstorm that morning then caused the the
Stamford Canal - Adding more water to the drains within a short period of time.
- Orchard road is made of a lot of impervious surface so there are a lot of runoffs, flooding the area.
What are runoffs:
See video of the flooding of Orchard Road :
How Marina Barrage is supposed to help reduce flood risks:
Marina Barrage helps reduce floods risks in low-lying areas of the city as Chinatown , Jalan Besar, Geylang, Boat Quay and Little India as it removes tidal influence from the Marina Reservoir. During heavy storms, when the reservoir water level is higher than the sea level, up to nine gates can be opened to discharge water from the reservoir into the sea. If the sea level is higher, up to six pumps can be activated to discharge excess storm water.
Marina Barrage flood gates
Videos of Marina Bay
Consequences of Flooding
Flash floods caused by heavy downpour on Wednesday morning in June wreaked havoc on many parts of central Singapore, flooding basement carparks and shops, and making roads impassable to cars. The worst-hit area was the Orchard Road and Scotts Road intersection, with large stretches from Paterson Road - where Ion Orchard and Wheelock Towers Ngee Ann City
Broken roads
Shops at the basement in Orchard Road were flooded with water
The basement of Liat Towers
A tree fell near the Buyong Road exit of the Central Expressway Tunnel, towards Ayer Rajah Expressway, blocking traffic across three lanes. The CTE was closed as a result, partly to prevent traffic from going into Orchard Road .
Other parts of central Singapore Coronation Road West , Fourth Avenue , Kings Road , Kheam Hock Road and Veerasamy Road were also affected, bringing traffic to a crawl.
Businesses affected
Carpark flooded, causing most of the cars to be damaged
Lost and damaging of many products
Flood Prevention or How to Lessen Flood Damage
a) Ideas on preventing flood from occurring again.
· Monitor and clear the drains every few weeks, especially when it is a wet month.
· Build high barricades around flood-prone areas
· Build a pumping station between a canal and low-lying areas to pump out water in case there is risk of flooding
·
The Stanford Cannel
A blocked culvert
· Upgrade reservoirs and build more floodgates to ease the amount of water flowing in.
· Use filtercrete to build the roads and pavements to prevent runoffs
· Filtercrete in Singapore
HydroSTON 50: Flag pavers used for tree surrounds in a pedestrian mall in New Upper Changi Road, Singapore
· See video about filtercrete:
http://www.youtube.com/watch?v=MPxPgLgdWws (how filtercrete works)
b) Ideas of lessening of flood damages:
· Build entrances of underground tunnels far above water level.
· Build excessive amounts of drainage whether we need it or not
· Check the drains more frequently.
· Build deeper drains and canals
· Insulate the electric cables with something water proof
· Get the PUB
· Make the marina barrage more effective
· Make some of the areas more grassy and not so much concrete in the city area so that there will be less runoffs and less floods
With the changes in global climate, heavy rainfall is not so infrequent anymore. Perhaps the assumptions made when we build our drains 20-30 years ago no longer holds and the risk to life and property from flash floods in a lot higher today. So it is time for us to wake up and make the effort to prevent floods from occurring again or continue tolerating another Orchard Road 's appearance.
Credits:
Pictures for question 1 (mechanics of flooding):
http://www.google.com.sg/imglanding?q=marina+barrage&um=1&hl=en&client=firefox-a&rls=org.mozilla:en-US:official&channel=s&biw=1229&bih=518&tbs=isch:1,isz:l&tbnid=lPf5dRYCUi0orM:&imgrefurl=http://www.news.gov.sg/public/sgpc/en/media_releases/agencies/pub/press_release/P-20090507-4.html&imgurl=http://www.news.gov.sg/public/sgpc/en/media_releases/agencies/pub/press_release/P-20090507-4/ImagePar/00/image/Marina%252520Barrage%252520%28aerial%252520view%29.jpg&zoom=1&w=1772&h=1181&iact=rc&ei=mfkuTfbsIYSIrAeRiqH8CA&oei=mfkuTfbsIYSIrAeRiqH8CA&esq=1&page=1&tbnh=151&tbnw=194&start=0&ndsp=10&ved=1t:429,r:0,s:0
Pictures for question 2 (consequences of flooding):
Pictures for question 3 (how to prevent floods/ lessening flood damage):
Done by: Alina Lam (16), Lynn Ng (22), Ang Shang le (28), Tai Jing Yu (36)
Class: 3C
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