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Are you living in a hole in the ground?

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Flash Floods seemed to be the ‘in’ thing these days. 

They are becoming so common these days, that they are rivalling the Flash Mob crowds, giving them a run for their money!

 But the only commonality they share is their sudden appearance and just as sudden, disappearance. Well, almost, in the case of the former!

 While the Flash Mobs would customarily disappear without much of a trace or hoo-ha, the same cannot be said of the Flash Floods! In their wake, we see or read about ruined carpets, ruined cars, ruined merchandise, ruined everything, including homes and business outlets!  

 Ok, this blog is not about joining in the finger-pointing or flaming brigade. Everybody knows the fault lies somewhere in between. It is half mother nature’s fault and half govt agencies’ fault! 

(NB. You can read a little more on this at the end of this post.) 

 Back to the main topic:

Through surfing the blogs, one realizes that there is indeed much to learn from the legions of experts patrolling cyberspace who cared enough to blog about it. So my advice to the PUB and NEA is that they should not feel shy about picking through these blogs for some useful pointers on offer, gratis! There is wisdom and a wealth of knowledge within waiting to be discovered.  

 Well, I too would like to do my modest bit with something I learned while ‘on the blog’ (couldn’t resist that)! 

 It is this: While there is really little we can do about where the next flood would be, or when it will come, it should be good to be at least mentally prepared for it – if you can have some ideas about the possibility of your home or business premises being ‘flashed’ by flood water.

In short, do you know whether you are living or working in a hole (or a bowl) in the ground?

With the Internet and Google, more precisely, with Google Earth, this information is available, within reach, with a little bit of patience and wrist work.

So, here goes, for those who want to know.

And for those who already know how to do it, please bear with me, this primer. Better, if you could pitch in with additional pointers. We can all learn together. :))

I would be glad to have your feedback. 


 I have actually prepared lots of screen shots to explain how to do it. I hope they would be sharp and clear enough. That seems the best way to go about it.

In order to follow and do what I am demonstrating here, you absolutely need to download (foc) and install Google Earth – get the latest free version. And you should have a reasonable graphics card which comes as standard on most PCs nowadays in any case. Windows OS: XP, Vista or 7 with at least 2 G RAM and a fast processor (gamer’s type, not essential), otherwise, your graphics would not be ‘smooth’. Sorry, I do not have similar info to offer Mac users. 


Pic 1. A view of a 'finished' product produced with the method I would be covering below. Click on the images to enlarge.


Pic 2. Using it to check out your location. Coloured texts and arrows are added by me for explanation.

Pic 3. Satellite pic of Sennett Est. which will be the location for the lesson. Step 1: Click Tool for the Ruler menu

Pic 4. Step 2: Ruler menu appears, click 'Line' and choose km

Pic 5. Step 3: Mouse pointer takes the shape of a 'box'. Use it to drag and draw line A-B (the yellow line)

Pic 6. Step 4: Give the line an ID or just a number eg. 1, and click 'OK' to save

Pic 7. Draw more lines as shown. Draw lines at right angle too, to form the 'net'

Pic 8. The 'net' is practically done

Pic 9. Now click Tools > Options > choose a profile exaggeration of '3' to better see the relief ('holes'!) from the options menu, leave the rest alone for the moment

Pic 10. You are now ready to check out the relief and profile, line by line, in both axes. Choose any line by placing your mouse pointer on it and right click. A menu would appear, choose 'Show Elevation Profile'

Pic 11. By moving the black vertical line in the profile chart below you will see where a point on the chart lies in the sat. pic above it. You can see a demo of this on Youtube at: http://www.youtube.com/watch?v=BrKcZXF2KM8

Pic 12. Final image in this lesson. Using the same procedure you can now track the horizontal axis (x). You can use this method anywhere on the island, in fact, on any place on Google Earth. See a demo on Youtube site : http://www.youtube.com/watch?v=Bmn2ujX_6pQ

Here is a small but connected digression from the main purpose of this posting:

It is quite apparent that the flash flooding is the result of high levels and high frequencies of direct surface runoff caused by the presence of widespread impermeable ground surfaces or conditions in urban build-up areas (eg. sealed roads and car parks). “Singapore is a ‘city’, remember? – to quote a minister”.

 The general terrain surface of Singapore is pockmarked throughout with ‘holes’ or depressions. We are not flat. These depressions are natural ponding places for water escaping from  an overflowing drainage system that has not been correspondingly upgraded to keep pace with the development of the concrete jungle. 

There is also a strong possibility that the recently commissioned Marina Barrage, constructed to create the Marina Reservoir by impounding water well above sea level, would have raised the level of the groundwater throughout the drainage system that feeds the reservoir.

This would have in turn reduced the capability of the ground to absorb rain water. The analogy would be a sponge that is already partially soaked with water. It’s capacity to absorb more water would be reduced compared to a dry or mostly dry sponge. It is likely that MORE flash flood can be expected during a wet spell period since a water-soaked ground would be too saturated to take in any more as it would not have sufficient time to dry out before the next heavy downpour. 

The barrage could also compromise the ability of the drainage system to hold and to channel the rainwater seawards since its standing water level would have been raised significantly by the water kept in by the barrage. The question remains whether the release of water into the sea at the barrage is done fast enough and early enough in response to a sudden and heavy downpour that seems to be happening with rather dismal regularity.     




  1. Cause of "Changing Weather Patterns" in Singapore says:

    TO: PUB
    SUBJECT: Longkang Water 101

    a)Rain falls from sky
    b)Rain water on the ground flows into drains
    c)Water in drain flows into bigger drains
    d)Water in bigger drain flows into canals
    e)Water in canals flows into rivers
    f)River water TRY but CANNOT flow into sea
    g)Blocked by Marina Barrage

    And that is how flooding starts.

    1. When was Marina Barrage put into operation? –
    Answer: 1 Nov 2008

    2. When did first great Orchard Road flood occur?
    Answer: 16 June 2010

    • thetwophilo says:

      A lead time of about one and the half year? The PUB would have been in the process of gradually reducing the salt water content of the impounded water by pumping the brackish water (mixture of sea and fresh water) out as more storm water flow in from the catchment. This dilution would be a continual process until the salinity has been reduced to an acceptable level. Also, it would take time for the floor of Marina Reservoir, which would be sea water permeated, to release its salt content with the constant dilution by fresh water. I don’t know much about the mechanism. Maybe, someone can explain?

  2. […] Great Singapore Floods – Thetwophilo’s Blog: Are you living in a hole in the ground? [Thanks […]

  3. xtrocious says:

    I don’t think it’s solely the fact of the Marina Barrage (although I used to think it was)…

    We must also not ignore the fact that a huge part of Orchard Road has been turned into a cavernous underground shopping mall…

    I believe that this would also reduce the ability of the ground to absorb water…

    Simple analogy would be comparing a cup filled with just sand and another with several large stones beneath the sand…the cup with just sand would definitely be able to “absorb” more water than the other one…

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