Thursday, September 22, 2011

20110920 SASC4 Case Study - Bukit Timah Canal

20110920 SASC4 Case Study - Bukit Timah Canal 
http://bettersingapore.blogspot.com/2011/09/20110920-sasc4-case-study-bukit-timah.html



Bukit Timah Canal is chosen not just because it has long flood history.


It is chosen because 
Serving heavier tropical rain forest storms
Over more than 7km mid-stream
The elevation is only 11 meter


Newton circle  16.334m (N1° 18´  47.05”  E103° 50´ 18.51”) 
Bukit timah    27.24m  (N1° 29 ´24.27” E 103° 46´ 45.29”) 
using Global Mapper  software


If we can resolve Bukit Timah, we can resolve most flood problems domestically as well as contribute to others, internationally.



A Precedence for others


Waterway design is a matured field, there are always precedence to refer to, to help us from errors, wastage, stifling flow.

20110830 PUB is digging deeper drains from 3 to 5.7 meter for Zion-Kim Seng 250m section of Alexandra Canal to mitigate flood upstream.

This is feeble, unproductive, even irrelevant. as stated.

We have done much bigger scale at Bukit Timah Canal - from Duchess to Kheam Hock road. 
Map, Satellite and photos showed the rapidly expanded width of the canal.






It is exactly at this location that gigantic downstream cannot support minute upstream flow !

Exactly one month after my written alarm on 2011 05 05  2011 06 05, Flood reported. 
Location of the flood is exactly before this drastic expansion of the drain. 

The smaller drains upstream can pump more water 
than 
the much bigger, broader downstream can carry !

 In front of Coronation Plaza
20110605 
Beside Adam-Lornie Flyover

Every serious engineers must provide facts and facts must be able to be clearly reasoned by logic. 

In the 
2011 05 05  report, a photo of flood on the second floor of the Environment Building, 
It was on an appointed time  (2007 08 24 Hrs 1107) i had with then Minister of MEWR Yaaccob Ibrahim.

A public building flooded on second floor, can only be without gradient or without maintenance, or both.
Digging any deeper, wider is a waste of resources.



Flow Speed Comparison - Canal

Flow speed for a drain was compared.

Now, let us see how fast the water flow on the expanded stream during a storm on the broadest section of Kheam Hock Road.



20110920 H1431
Slow flow even immediately after heavy rain
Bukit Timah Canal at Kheam Hock Section


20110720 H1256
Lamp Post 260 Bukit Timah Canal Dry Season
(note the river was narrowed  at downstream)


20110720 H1512
Wayang Satu Flow Stopping
Note this is a 40MB MP4 video which may take time to load



Analogy of Giant and Sprinter

The high speed of flow upstream needs to push the immense inertia of a much bigger almost stagnating downstream, can be visualized as following:





This is something very obvious to mechanical engineers.
Mechanical engineers therefore often be called upon to help civil engineers in rapidly, effectively, resolutely resolve most teething issues.




Resources Ignored, Abandoned to waste


Clearly, a wastage of gradient upstream and excessive depth and size mid stream of Bukit Timah canal is the root cause of the continuous flood.

If you invest in the wrong approach, no matter how big you invest, can never make it correct.



This often come about ignoring, abandoning important resources, alternatives.
The following showed 

  1. at Robin Road,  downstreams from Kheam Hock road, canal is narrowed from > 30m to < 20m and diverted at right angle.
  2. at Chancery Lane, downstreams of Robin Road, there is a dam totally blocking of the flow to Newton circle.
  3. We can see right handside of Robin diversion, the drains is dried, and ill-maintained







20110920 SASC1 -  Waterway Design for Global Warming 
20110920 SASC3 What Impede Flow - Over-sized Excessive Depth 

Please help me to Examine, Correct, and Improve 
Strengthen Singaporeans to serve the greater World




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