The population, commercial and industrial expansion of Hong Kong, particularly over the last 60 years, has resulted in a degradation of its coastline and marine environment. Perhaps the most notable activity that has caused this degradation is Land Reclamation.
As we identified early on in this blog, Hong Kong possesses a huge, expanding population that is requiring more and more land in order to live, work and survive. To fulfil this demand Hong Kong has frequently utilised land reclamation techniques.
What?
Simply put, it is the building up of the sea bed to create an above sea-level surface that is stable enough for further construction or other development. There are various methods used for achieving this build up but broadly speaking they involve the replacement of the soft silt sediments on the seabed with large deposits of rocks (Yan et al, 2013).When?
The earliest reports of land reclamation in China originated from the Western Han Dynasty where coastal areas were reclaimed in order to create terraces for the recovery of salt from sea water.Modern reclamation, as we would consider it (i.e. the creation of land for industry etc), began in Hong Kong during the mid 19th Century (Jiao, 2000) shortly after the beginning of the British occupation. Large areas of marshland close to the harbour were bought and reclaimed by traders wishing to create easy access to the harbour.
Since those initial projects, land reclamation has been undertaken on much larger scales culminating in an estimated 10% increase in land surface across Hong Kong by 2000. Furthermore, this increase is due to accelerate with the recent commencement of several larger scale industrial projects (Jiao et al, 2000). The graphic below gives an impression of how reclamation projects have advanced from their humble beginnings and have predominantly been focused on both sides of Victoria harbour with more recent undertakings towards the western edges of Lantau and the New territories.
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| Estimates of the evolution of land reclamation across Hong Kong, courtesy of www.scmp.com |
Where?
Two of the most recent reclamation projects carried out (and in fact still being carried) in Hong Kong are the construction of the HK International Airport and the construction of the Macau-Zhuhai-Hong Kong Bridge:
Hong Kong International Airport
Take another quick look at our 'evolution of land reclamation' graphic; you see the huge area on the northern edge of Lantau? That's the site of Hong Kong's newest airport and home to over 12km^2 of reclaimed land, Hong Kong's largest, completed reclamation project so far (Plant et al, 1998).If you're desperate for a little more on reclamation methods here's a link for a promo video released on Hong Kong International airports offical youtube channel, I won't embed the video because its seriously cheesy and saccharine with the positive (marketing) aspects of reclamation, but it does offer a brief synopsis of the reclamation project: HK Airport Reclamation.
Hong Kong - Zhuhai - Macau Bridge (HZMB)
A little further west from the airport is the bridge project which aims to be the first step in connecting three of the largest population centres of the Pearl River Delta (China's industrial centre) through a combination of bridge and tunnel networks. A large portion of this project is the creation of a series of new islands.Preparatory construction work for the bridge commenced in late 2009 and has a predicted completion data of 2016 (ARUP website, 2010) .
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| Route of the New bridge, courtesy of www.NCE.co.uk |
Impacts
It seems logical that the deposition of 1000s of tons of material into a coastal area is perhaps one of the most powerful impacts to which we could subject a marine environment. Jefferson et al, (2009) created an informal hierarchy of 'development activities' associated with the industrialisation of Hong Kong and their respective impacts on the marine environment which placed land reclamation at the top of the list.
Those of you who tuned in last week may also notice that these two examples are placed, at least partially, within the same zone that the WWF Hong Kong identified as containing White Dolphin populations. Hung et al (2004) confirm that the ranging area of the dolphin populations identified across the Pearl River Estuary extend across western Hong Kong waters, although they go on to state that further investigation of true numbers are required. Regardless, it is clear that the reclamation being undertaken for these projects will have an impact upon these local cetacean populations.
Aside from the complete removal of swathes of environment, there are additional impacts relating to the upcast sediments and potential contaminants sealed within these deposits. Yan et al (2013) provide a case study for the future off-shore airport at Jinzhou Bay that models the impacts of two reclamation methods: Underwater Explosion and Silt dredging.
A quick aside: for any Environmental Modelling MSc people out there I really recommend having a look over the case study I mentioned earlier (Yan et al, 2013). It's a good example of a modern project involving comparisons, predictions and evaluations through model application and is the kind of work that any of us may be involved with in the future.
And now, as promised....porpoises!
Those of you who tuned in last week may also notice that these two examples are placed, at least partially, within the same zone that the WWF Hong Kong identified as containing White Dolphin populations. Hung et al (2004) confirm that the ranging area of the dolphin populations identified across the Pearl River Estuary extend across western Hong Kong waters, although they go on to state that further investigation of true numbers are required. Regardless, it is clear that the reclamation being undertaken for these projects will have an impact upon these local cetacean populations.
Aside from the complete removal of swathes of environment, there are additional impacts relating to the upcast sediments and potential contaminants sealed within these deposits. Yan et al (2013) provide a case study for the future off-shore airport at Jinzhou Bay that models the impacts of two reclamation methods: Underwater Explosion and Silt dredging.
- As the name implies the 'Underwater Explosion' method of soft silt removal is through the explosion of Trinitrotoluene (TNT) packages that are placed deep within the sediments. The explosion leaves the sediment, and any previously sealed contaminants suspended in the water allowing rock deposits, that were previously dumped on top of the sediment, to enter the newly cleared area. This method can have two catastrophic effects on marine ecology: the primary explosion can disorientate, or even kill marine life, particularly those that possess carefully balanced swim-bladders (Jefferson et al, 2009), within a given radius whilst the dense spread of suspended sediment can extend across huge areas destroying the ability of phytoplankton to photosynthesise and negatively affecting zooplankton growth (Yan et al, 2013).
- The 'Silt Dredging' method involves the construction of dredgers which suck up the silt and deposit it elsewhere. This method lacks the severe impact of the former, but possesses the same risk of disturbing contaminated sediments whilst also requiring an additional area for dumping of the extracted deposits.
A quick aside: for any Environmental Modelling MSc people out there I really recommend having a look over the case study I mentioned earlier (Yan et al, 2013). It's a good example of a modern project involving comparisons, predictions and evaluations through model application and is the kind of work that any of us may be involved with in the future.
And now, as promised....porpoises!
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| D'AAAAAW!!!! courtesy of www.china.org.cn |
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