Contents
2 Summary of Environmental
Monitoring and Audit Requirements
3 Review of Chinese White Dolphin
Monitoring Results
4 Review of Landscape Establishment
Monitoring Results
5 Review of the Validity of EIA
Predictions
6 Recommendations and Conclusions
Table 1.1: Contact
Information of Key Personnel
Figures
Figure 1 Transect Line Layout in West Lantau
Survey Area
Appendices
Appendix A Project Organisation for Environmental
Works
Appendix
B Chinese White Dolphin Monitoring
Results
Appendix
C Landscape Establishment Monitoring
Results
Appendix D Summary of Weather Conditions
This Final Environmental Monitoring and
Audit (EM&A) Review Report is prepared for Agreement No. HMWSD 1/2019 (EP)
“Post-Construction Monitoring of Chinese White Dolphin (Line-transect Vessel
Surveys) for the Hong Kong-Zhuhai-Macao Bridge Hong Kong Link Road at West
Lantau Waters – Investigation” (hereafter referred to as “the Assignment”) for
the Highways Department of Hong Kong Special Administrative Region (HKSAR).
Mott MacDonald Hong Kong Limited was
appointed by the Highways Department of HKSAR to undertake the Environmental
Team services for this Assignment to conduct the post-construction monitoring
of Chinese White Dolphin in West Lantau waters for 14 months of line-transect
vessel surveys and to prepare all the post-construction phase quarterly summary
reports for the Hong Kong-Zhuhai-Macao Bridge Hong Kong Link Road Project.
Construction phase of the Project was completed in October 2018.
This is the Final EM&A
Review Report for the 24-month post-construction phase of the Project
summarising the findings of the post-construction EM&A activities in the
period between November 2018 and October 2020.
Environmental
Monitoring Works in the Post-Construction Phase
All Chinese White Dolphin monitoring and
landscape establishment monitoring works were conducted as scheduled under the
24-month post-construction phase. As all marine-based construction activities
of the Project were completed in October 2018, no construction works were
involved during the post-construction monitoring period. A summary of the post-construction
monitoring works is listed as below:
Parameter |
Monitoring
Dates |
Chinese
White Dolphin Monitoring (Line-transect Vessel Surveys) |
5th
and 12th November 2018 6th
and 13th December 2018 4th
and 8th January 2019 12th
and 15th February 2019 6th
and 20th March 2019 3rd
and 24th April 2019 9th
and 16th May 2019 4th
and 17th June 2019 5th
and 11th July 2019 12th
and 28th August 2019 19th
and 25th September 2019 2nd
and 16th October 2019 4th
and 26th November 2019 2nd
and 4th December 2019 8th
and 15th January 2020 5th
and 12th February 2020 6th
and 11th March 2020 1st
and 17th April 2020 6th
and 20th May 2020 2nd
and 22nd June 2020 6th
and 13th July 2020 6th
and 10th August 2020 8th
and 24th September 2020 5th
and 8th October 2020 |
Landscape
Establishment Monitoring (bi-monthly, conducted for Contract No.
HY/2011/09 by other parties) |
1st
August 2019 23rd
September 2019 29th
November 2019 10th
January 2020 20th
March 2020 11th
and 22nd May 2020 |
Conclusion
of Post-Construction Monitoring
The post-construction phase EM&A
programme of environmental monitoring works has been undertaken in the period
between November 2018 and October 2020. The CWD usage in WL region has been
monitored throughout the post-construction phase of HKLR Project to examine
whether CWDs are affected by the lingering impacts from the construction works.
The landscape establishment monitoring has been conducted bi-monthly and
completed to ensure the aims of the landscape and visual mitigation measures
proposed during EIA stage are met.
The Hong Kong-Zhuhai-Macao Bridge (HZMB)
Hong Kong Link Road (HKLR) is a designated project under the Environmental
Impact Assessment Ordinance (EIAO). The
Environmental Impact Assessment (EIA) Report and Environmental Monitoring and
Audit (EM&A) Manual (EIA Register No.: AEIAR-144/2009) for the project were
approved by the Director of Environmental Protection in October 2009 and the
Environmental Permit No. EP-352/2009 (EP) was issued in November 2009. The EP has been subject to several variations
and the current one is EP No. EP-352/2009/D.
The HZMB HKLR was constructed under two
works contracts namely Contract No. HY/2011/03 (HZMB HKLR – Section between
Scenic Hill and Hong Kong Boundary Crossing Facilities (HKBCF)) and Contract
No. HY/2011/09 (HZMB HKLR – Section between HKSAR Boundary and Scenic
Hill). In accordance with the EP, the
Contractors of Contract No. HY/2011/03 and Contract No. HY/2011/09 have
separately employed their own Environmental Team (ET) and ET Leader to conduct
construction phase monitoring of Chinese White Dolphin (CWD) in the North
Lantau (NL) and West Lantau (WL) waters following the requirements specified in
the EM&A Manual and the relevant contract specifications of the two
contracts.
In accordance with Section 10.3 of the
EM&A Manual, an ecological monitoring and audit programme is needed which
will monitor potential impacts through construction and operation activities,
and will verify the assessments which were made in the EIA report. In particular, the programme should include
dolphin monitoring at NL and WL waters to be set up in order to verify the
predictions of impacts and to ensure that there are no unforeseen impacts on
the dolphin population during construction phase. Such dolphin monitoring should cover the
pre-construction phase, the entire period of construction phase and after the
completion of construction works (i.e. post-construction phase). In accordance
with Section 14.2.1 of the EM&A Manual, mitigation measures for landscape
and visual impacts implemented during construction phase should be checked
every 2 months to ensure compliance with the intended aims throughout the
one-year landscape establishment period in the post-construction phase.
The main objective of the current
Assignment commissioned by the Highways Department (HyD)
is to conduct Post-Construction Monitoring of CWD in WL waters in compliance
with the requirements stipulated in the EM&A Manual and the EP for the HZMB
HKLR Project. The post-construction
monitoring of CWD should be conducted for 24 months upon the completion of all
marine-based construction activities. CWD monitoring of the baseline
(pre-construction) phase was conducted for 12 months from February 2011 to
January 2012. The construction phase CWD monitoring of HZMB HKLR Project lasted
for 72 months from November 2012 to October 2018 when the marine-based
construction activities for the Contract No. HY/2011/09 was completed in
October 2018. Subsequently, 10 months of post-construction dolphin monitoring
had been carried out by the Contract, while the remaining 14 months of
post-construction dolphin monitoring were completed under this Assignment, from
In August 2019, Mott MacDonald Hong Kong
Limited was appointed by the HyD to undertake the
Environmental Team (ET) services for this Assignment to undertake the
post-construction monitoring of CWD in WL waters (refer to Figure
1) for the HZMB HKLR Project.
This is the Final EM&A
Review Report for the post-construction phase of the Project summarising the
findings of the post-construction EM&A activities in the period between
November 2018 and October 2020, and is submitted to fulfil Section 16.5 of the
EM&A Manual.
The project organisation and lines of
communication with respect to the environmental management structure are shown
in Appendix A.
The key personnel contact names and numbers are summarised in Table 1.1.
Party |
Position |
Name |
Telephone
|
Fax |
Permit
Holder (HyD) |
Engineer |
Mr. Wei
Chen |
2762 3532 |
3188 6614 |
Environmental
Project Office / Independent
Environmental Checker (Ramboll
Hong Kong Limited) |
Environmental
Project Office Leader |
Mr. Y H
Hui |
3465 2888 |
3465 2899 |
Independent
Environmental Checker |
Mr.
Manson Yeung |
3465 2836 |
3465 2899 |
|
Environmental
Team (Mott
MacDonald Hong Kong Limited) |
Environmental
Team Leader |
Mr. Gary
Chow |
2828 5874 |
2827 1823 |
As described in Section 1.1, the Assignment
is under the post-construction phase of the HZMB HKLR Project from November
2018 to October 2020 with all marine-based construction activities completed,
thus there were no construction works involved during the 24-month
post-construction monitoring period.
All CWD monitoring and landscape
establishment monitoring works were conducted as scheduled under the
post-construction phase of the Project.
According to the requirement stated in
the EM&A Manual, a CWD monitoring programme was set up to conduct surveys
for twice per month throughout the entire post-construction monitoring period
for 24 months, adopting the line-transect vessel survey method and covering the
following transect lines in the West Lantau (WL) survey area as in the AFCD
long-term marine mammal monitoring programme.
The CWD monitoring works were undertaken
by a dedicated survey team comprising qualified dolphin specialist and
experienced CWD surveyors. The qualified dolphin specialist was approved by the
AFCD and EPD.
The location of the WL survey area and
all transect lines are depicted in Figure 1.
The co-ordinates of all transect lines are shown in Table 1 of Appendix
B.
The monitoring protocol is detailed in
Section 3 of Appendix
B which is consistent and compatible with the methodology for dolphin
monitoring during baseline and construction phases.
Data analysis and assessment in the
final review report will be more detailed including distribution analysis,
encounter rate analysis, abundance and density estimates, quantitative grid
analysis on habitat use, behavioural analysis, ranging pattern analysis,
comparison between baseline, construction and post-construction phases of HKLR,
and assessment of any recovery in dolphin usage in WL waters. Details of
approach and methodology for these analyses and assessment are provided in
Section 4 of Appendix
B. Notably, although the official baseline dolphin monitoring under the
HKLR EM&A programme was conducted during a three-month period of September
2011 to November 2011 under the requirement, this relatively short study period
would not be sufficient to reliably establish the baseline condition on dolphin
occurrence, as the three-month period would not take into account the seasonal
variation in dolphin occurrences. As
there were additional monitoring data collected (under a separate assignment
commissioned by the Highways Department) before and after the three-month
official baseline period, a 12-month baseline monitoring period from February
2011 to January 2012 (which included the original baseline period of September
– November 2011) is adopted instead in this Final EM&A Review Report, and
such 12-month baseline monitoring period in 2011 – 2012 was still well before
the commencement of HKLR construction.
According to the requirement stated in
the EM&A Manual, landscape establishment monitoring should be carried out
every two months for checking of the planting works during the one-year
establishment period. Measures to mitigate landscape and visual impacts should
be checked to ensure compliance with the intended aims of the measures.
The landscape establishment monitoring
areas locate along South Perimeter Road and Chek Lap Kok South Road, near Scenic Road and a small section of
Airport Road and Kwo Lo Wan Road. The monitoring
programme was set to be conducted in bi-monthly intervals throughout the
landscape establishment period for one year from July 2019. The monitoring has
been conducted since July 2019 by other parties for Contract No. HY/2011/09,
with details provided in Appendix C.
During the 24-month
post-construction monitoring period from November 2018 to October 2020, a
total of 48 sets of systematic line-transect vessel surveys were conducted to
cover all transect lines in WL survey area twice per month. From these surveys,
a total of 1,583.63 km of survey effort was collected, with 94% of the total
survey effort being conducted under favourable weather conditions (i.e.
Beaufort Sea State 3 or below with good visibility). The total survey effort conducted on primary
lines was 1,049.17 km, while the effort on secondary lines was 534.46 km. Survey effort conducted on primary and
secondary lines were both considered as on-effort survey data. A summary table of the survey effort is shown
in Appendix
B.
During the post-construction monitoring
period, a total of 173 groups of 583 dolphins were sighted. Among them, 165
groups of sighting were made on-effort, with 107 on-effort sightings made on
primary lines. A summary table of the dolphin sightings is shown in Appendix
B.
For the overall CWD monitoring in WL
waters for the HZMB HKLR Project, 572.20 km of survey effort were conducted
during the 12-month baseline monitoring period between 2011 and 2012, and
another 4,765.22 km of survey effort were conducted during the 72-month
construction phase monitoring period between 2012 and 2018. A total of 113 groups of 380 dolphins were
sighted during the baseline monitoring phase, while 670 groups of 2,499
dolphins were sighted during the construction phase monitoring.
Distribution of dolphin sightings made
during the post-construction monitoring period is shown in Figure 1 of Appendix
B. The sightings were evenly
distributed from Tai O Peninsula in the north to Fan Lau in the south, with
higher concentration near Tai O Peninsula, Kai Kung Shan, Peaked Hill and Fan
Lau (Figure 1 of Appendix
B). On the contrary, dolphin
groups appeared to avoid the inshore waters between Tai O Peninsula and Kai
Kung Shan, as well as the HKLR alignment and the southern end (i.e. transect
line 12) of the survey area where it overlapped with the South Lantau Vessel
Fairway.
The distribution patterns of dolphin
sightings in WL waters amongst the nine 12-month monitoring periods spanning
across the baseline, construction and post-construction phases of HKLR is shown
in Figure 2 of Appendix
B. Comparing these distribution
patterns, some subtle differences were found. There was a gradual decline in
dolphin occurrence in the northern portion of WL survey area over the years,
with apparent avoidance of the HKLR alignment in recent years when compared to
the earlier years. Moreover, dolphin
usage at several key habitats including the Tai O Peninsula, Kai Kung Shan,
Peaked Hill and Fan Lau Peninsula, have fluctuated across different years, with
no apparent trend. However, it is
apparent that dolphin occurrence in WL waters was at the lowest level in the
last 12-month monitoring period (i.e. post-construction monitoring period in
2019 – 2020).
For the entire post-construction monitoring
period, the monthly encounter rates of CWD deduced from the survey effort and
on-effort sighting data from the primary transect lines under favourable
conditions (Beaufort 3 or below) from West Lantau survey area are shown in
Table 2 of Appendix
B. The average encounter rates deduced from each quarterly period were
presented in Table 3 of Appendix
B.
A comparison is made amongst the nine
12-month monitoring periods spanning across the baseline, construction and
post-construction phases of HKLR, as shown in Table 4 of
Appendix
B. It revealed that dolphin
encounter rates continued to decline during the first several years of HKLR
bridge construction works to the lower point in 2016 – 2017. Then, there was a rebound in the encounter
rates during 2017 – 2018, but it was subsequently followed by another decline
during the post-construction monitoring period to the lowest point in encounter
rate STG and the second lowest point in encounter rate ANI in 2019 – 2020.
A linear regression analysis was
conducted to examine whether there were any significant differences in the
average encounter rates between the baseline, construction and
post-construction monitoring periods.
Such comparison showed that the p-value for the decline in average
dolphin encounter rates STG and ANI were 0.000085 and 0.000980 respectively,
indicating a significant downward slope across the nine 12-month monitoring
periods in the baseline, construction and post-construction phases.
Densities and abundances of CWD in WL
waters were estimated during different phases of the Project using the
line-transect analysis method, following similar approach as in AFCD long-term
marine mammal monitoring study. The following two types of comparison are
conducted to review the impact of HKLR construction on CWD densities and
abundances, as presented in Table 5 of Appendix B:
1.
Among
the three phases of the Project, i.e. baseline phase vs. construction phase vs.
post-construction phase; and
2.
Among
the nine 12-month monitoring periods spanning across the three phases of the
Project.
For the comparison among the three
phases of the Project, the baseline phase in 2011 – 2012 recorded the highest
dolphin density and abundance, with around 113 dolphins per 100 km2
or 31 dolphins. The CWD estimates dropped to a lower level during the
construction phase in 2012 – 2018, with around 79 dolphins per 100 km2
in density or 22 dolphins in abundance. Then, the CWD density and abundance
fell even further to the lowest level during the post-construction phase in
2018-20, with around 55 dolphins per 100 km2 or 15 dolphins.
Among the nine 12-month monitoring
periods across the three phases of the Project, there was a noticeable drop
between the baseline period and the first construction period, falling from 31
dolphins in 2011 – 2012 to 21 dolphins in 2012 – 2013 (as shown in Table 5 of Appendix B). After a
noticeable rebound in 2013 – 2014 with 29 dolphins, the dolphin abundance
progressively declined to a lower level in 2016 – 2017 with only 15
dolphins. Then once again, there was a
rebound in 2017 – 2018 with 22 dolphins during the last construction period,
before falling back to the lowest level during the post-construction phase in
2018 – 2019 and 2019 – 2020 with only 15 and 14 dolphins respectively.
For the examination of any significant
temporal trend among the nine 12-month monitoring periods using linear
regression models, the test statistics for hypotheses Ho: b = 0
vs. H1: b < 0 is -3.7728 whose p-value ≈ 0.0000 < 5%. The hypothesis Ho is rejected at 5% level of
significance. Therefore, it can be
concluded that the dolphin abundance estimates from the nine 12-month
monitoring periods in WL possesses a downward sloping trend, and the decline
was statistically significant.
Notably, the coefficient of variations
(CVs) of estimates for all the nine 12-month monitoring periods remained fairly
low (all within 15% – 22% as shown in Table 5 of Appendix B), and therefore
these estimates are considered to be reliable.
During the post-construction monitoring
period, group size of CWD ranged from one to 19 animals per group in WL survey
area. Among the 173 groups of dolphins, 131 groups (75.7%) were in small group
sizes of 1-4 dolphins. On the contrary, 34 groups were moderate in size with
5-9 dolphins, while another eight groups were large in size with 10-19 dolphins
(sighting details refer to Appendix B).
The average dolphin group size recorded
during the nine 12-month monitoring periods across the three phases of the
Project are also compared, as shown in Table 6 of Appendix B. When compared to
the baseline phase, the average dolphin group sizes were noticeably higher in
the second and third years (2013 – 2015) as well as the latter part (2017 –
2018) of the construction phase, while other years were slightly above or below
the baseline average, with no apparent overall trend across different years.
Distribution of dolphins with relatively
larger group sizes (with five or more animals per group) is examined during the
post-construction monitoring period and is shown in Figure 3 of Appendix B. The 34 medium-sized groups (with 5-9 animals
per group) were mostly sighted in the middle portion of the WL survey area
(i.e. between Tai O Peninsula and Peaked Hill), while the eight large groups
(with 10-19 animals per group) were evenly distributed across the WL survey
area with no particular concentration.
Distributions of dolphins with
relatively larger groups during the nine 12-month monitoring periods across the
three phases of the Project are also examined and presented in Figure 4 of Appendix B. The distribution
pattern of dolphins with larger group sizes varied widely, with more even
distribution and higher occurrences during the baseline phase (2011 – 2012), as
well as the second and sixth years of construction phase (2013 – 2014 and 2017
– 2018). Notably, during the second year of post-construction monitoring (2019
– 2020), larger dolphin groups have mostly disappeared from the northern
portion of WL survey area, which was in stark contrast to such distribution
recorded during the baseline period.
During the post-construction monitoring
period from November 2018 to October 2020, the grids that recorded higher
densities of dolphins were located to the north and west of Kai Kung Shan, near
Peaked Hill and Fan Lau, while the grids around and to the north of Tai O
Peninsula mostly recorded lower dolphin densities, as shown in Figures 5a &
5b of Appendix B.
When compared with the habitat use
pattern recorded among the nine 12-month monitoring periods across the
baseline, construction and post-construction phases, it appears that the
overall dolphin densities across the WL survey area has declined since the
construction commenced in 2012 – 2013, as depicted in Figure 6 of Appendix B. Furthermore, among
the several important dolphin habitats in this survey area (including Tai O
Peninsula, Kai Kung Shan, Peaked Hill and Fan Lau), only the one at Fan Lau has
consistently recorded high dolphin densities across the nine 12-month
monitoring periods.
Throughout the post-construction
monitoring period (2018 – 2020), a total of 20 young calves were sighted with
the mother in the WL survey area. These included four unspotted calves
(new-born ones) and 16 unspotted juveniles (older calves). The 20 young calves
comprised 3.4% of all animals sighted during the post-construction monitoring period,
which was similar to the percentage recorded during the construction phase in
2012 – 2018 (3.2%), but lower than the one recorded during the baseline phase
in 2011 – 2012 (5.8%).
The majority of the 20 young calves
sighted during the post-construction monitoring period were distributed in the
central portion of WL survey area, i.e. between the Tai O Peninsula and Peaked
Hill. A few other young calves were also sighted near Fan Lau and just to the
north of the HKLR alignment (see Figure 7 of Appendix B).
Distribution of young calves during the
nine 12-month monitoring periods across the three phases of the Project are
also presented in Figure 8 of Appendix B. In comparison with
the distribution of young calves during the baseline monitoring period, the
young calves appeared to have avoided the northern portion of WL survey area,
especially to the north of Tai O Peninsula, during the latter half of the
construction monitoring period (2015 – 2018) as well as the 24-month
post-construction monitoring period (2018 – 2020).
During the post-construction monitoring
period, a total of 10 and eight groups of dolphins were engaged in feeding and
socializing activities respectively, while none of the 173 dolphin groups was
engaged in traveling or milling/resting activity. The 10 groups of dolphins
engaged in feeding activities comprised 5.8% of the total number of dolphin
groups sighted during the post-construction monitoring period, which was much
lower than the percentage recorded during the baseline (10.6%) or the
construction monitoring period (11.0%).
On the other hand, the eight dolphin groups engaged in socializing
activities during the post-construction monitoring period comprised 4.6% of the
total, which was comparable to the ones recorded during the baseline (5.3%) and
construction monitoring period (4.4%).
In the post-construction phase, the
dolphin groups engaged in feeding activities were found sporadically throughout
the WL survey area with no particular concentration, as shown in Figure 9 of Appendix B. Notably, two of the 10 groups were found
feeding near the HKLR alignment. On the
other hand, the dolphin groups engaged in socializing activities were mostly
distributed in the central portion of WL survey area, between Tai O Peninsula
and Peaked Hill.
Distribution of dolphin activities
during the nine 12-month monitoring periods of the Project are also presented
in Figure 10 of Appendix B. Distribution of
feeding and socializing activities engaged by the dolphins varied widely
without any particular concentration in the nine 12-month monitoring periods
across the baseline, construction and post-construction phases.
Among the 173 groups sighted during the
post-construction monitoring period, three of them were associated with
operating fishing vessels (two with gill-netters and one with a purse-seiner),
with all of them occurred during a three-month period of February to April 2019
(see sighting details in Appendix B). In comparison, six of the 113 dolphin groups
(5.3%) and 21 of the 670 dolphin groups (3.1%) were associated with operating fishing
vessels during the baseline and construction monitoring periods respectively,
and both percentages were much higher than the one recorded during the
post-construction monitoring period (1.7%).
In the post-construction monitoring
period, 136 individuals sighted 382 times altogether were identified (see the
summary table and photographs of identified individuals in Appendix B). Among them, 82 individuals were re-sighted
once or twice. In contrast, there were
54 individuals being re-sighted three times or more during the 24-month period,
including 35 individuals being re-sighted 3 to 5 times, while 16 individuals
being re-sighted 6-8 times. Two individuals (CH108 and WL123) were re-sighted
nine times and another individual (WL79) were re-sighted 13 times during the
post-construction monitoring period, showing their strong reliance to the WL
waters in 2018 – 2020.
Ranging patterns of the 132 individuals
identified during the post-construction monitoring period and accumulated with
at least five re-sightings were determined by fixed kernel method, as shown in Appendix B.
Besides some individuals (e.g. NL33,
NL123, NL261, NL322, WL05) occurred in both North and West Lantau waters, there
were also a number of individuals (e.g. NL156, NL224, NL242, NL259, WL11) being
primarily sighted in North Lantau waters in the past, but were re-sighted in WL
waters during the post-construction phase monitoring period. On the other hand,
the majority of the 132 individuals were sighted well within their normal home
ranges in WL waters as in the past, while some of them (e.g. WL109, WL123,
WL152, WL221, WL281) have extended their range use more often into South Lantau
waters during the post-construction phase monitoring period.
Among the 136 individuals sighted during
the post-construction monitoring period, only 32 of them were sighted before
the HKLR construction commenced in the last quarter of 2012. To examine whether there has been any changes
in their range use before and after the HKLR construction, their ranging
patterns before October 2012 (i.e. range use during baseline phase) and after
November 2018 (i.e. range use during post-construction phase) are compared in Appendix B. For these 32
individuals, several parameters are evaluated for any temporal changes in their
range use, which include the changes in level of utilization, any expansion,
contraction or shifts in range use, and how shifts from one area to another
have occurred. Further examination is also
made to determine if these individuals have avoided the bridge alignment after
the HKLR construction, and whether the physical presence of the bridge
alignment has hindered their north-south movement between NL and WL waters.
On the level of utilization, 11
individuals have occurred much less often in the western waters of Hong Kong
during the post-construction monitoring period (e.g. NL212, WL15, WL46), while
the majority of individuals have occurred more or less the same between the
baseline and post-construction phases.
Furthermore, 14 of the 32 individuals have either moved away from or
occurred much less often in NWL waters (e.g. NL120, WL179), while another 15
individuals have utilized the Southwest Lantau waters more often during
post-construction phase when compared to the baseline period (e.g. WL61,
WL123).
In addition, the ranges of 13
individuals have shrunk considerably during the post-construction monitoring
period (e.g. NL224, SL42, WL128), but only two have expanded at the same time
(NL261 and WL61). Eleven individuals
have also shown clear range shifts during the post-construction period when
compared to the baseline phase, with four clearly shifted from North Lantau to
West Lantau waters (e.g. NL120, WL179), and another 11 individuals having
notable expansion from West Lantau into Southwest Lantau waters during the
post-construction phase (e.g. WL98, WL130, WL131).
Out of the 32 individuals, 21 of them
have their ranges overlapped with the bridge alignment before HKLR
construction, and therefore their range use in relation to HKLR construction is
further examined. During the
post-construction monitoring period, 12 of them have avoided the HKLR alignment
(e.g. WL21, WL42), and it appeared that the bridge may have limited or hindered
the north-south movement of two-third of these 21 individuals across HKLR
alignment (e.g. NL212, WL98 refer to ranging patterns in Appendix B).
There was a gradual decline in dolphin
occurrence in the northern portion of WL survey area in the past decade, with
apparent avoidance of the HKLR alignment in recent years. Dolphin occurrence was also at the lowest
level at the last 12-month period of post-construction monitoring in 2019 –
2020 among the nine 12-month monitoring periods across the baseline,
construction and post-construction phases of the HKLR Project.
Aside from a rebound in 2017 – 2018,
dolphin encounter rates continued to decline from the baseline monitoring
period to the lowest point during the post-construction monitoring period.
Furthermore, dolphin abundance estimates from the nine 12-month monitoring
periods possesses a downward sloping trend, and such decline is statistically
significant.
Regarding dolphin group size, there was
no apparent overall trend in average group size across different phases of HKLR
Project. Notably, during the second year of post-construction monitoring in
2019 – 2020, larger dolphin groups have mostly disappeared from the northern
portion of WL survey area, which was very different from the baseline
monitoring period.
Overall dolphin densities across the WL
survey area have declined since the HKLR construction commenced in 2012 –
2013. Among the several important
dolphin habitats in WL waters, only the waters at Fan Lau has consistently been
utilized by dolphins at a high level before, during and after HKLR
construction.
Regarding occurrence of mother-calf
pairs, young calves appeared to have avoided the northern portion of WL survey
area during the latter half of construction monitoring period as well as the
entire post-construction monitoring period.
For dolphin activities, the percentage
of dolphin groups engaged in feeding activities during post-construction
monitoring period was much lower than the one recorded during the baseline and
construction monitoring periods, but the percentage of dolphin groups engaged
in socializing activities were similar across the three phases.
Among the 21 individuals being assessed
for their range use before and after HKLR construction, more than half of them
have avoided the HKLR alignment during the post-construction monitoring period,
and the bridge may have also limited or hindered the north-south movement of
two-third of these individuals across the HKLR alignment.
Supplementary studies have been
conducted under the HKLR EM&A Programme to understand the potential impacts
of underwater noise, dolphin acoustic behaviour and north-south movement from
the HKLR construction works in WL. As these studies are useful for
complementing the vessel-based line-transect survey results as detailed above,
they will also facilitate the review on the validity of EIA predictions and
assessment on the effectiveness of mitigation measures.
During the EIA stage, there were
concerns that during and after HKLR construction the movement of dolphins
across the bridge alignment to range between NL and WL waters may be affected.
Therefore, a shore-based theodolite tracking study at Sham Wat Station was
conducted as part of the EM&A requirement to examine the north-south
movement of dolphins before and during the HKLR bridge construction.
A total of 112 and 200 tracks of dolphin
movements were obtained during the baseline and construction phases
respectively. The locations (in geographical coordinates) of each track were
analysed to determine whether the dolphins were entirely on the north or south
side of the HKLR alignment, or crossing through the HKLR alignment. Different
proportions of such crossings or non-crossings were compared between the two
phases, i.e. before and during the construction works.
During the baseline period without any
construction works at the waters off Sham Wat, 20% of dolphin tracks passed
through the bridge alignment. However, such percentage dropped dramatically to
only 5% in 2014 (the first full year of HKLR construction), when bored piling
works were the most intense, and the spacing between bridge piers became
progressively narrower with multiple fronts. Even though there was a strong
rebound in 2015 to 29%, such percentage fell back to a much lower level in
subsequent years.
The study on north-south movement of
dolphins concluded that such level of movements remained at a very low level in
the past several years, without any sign of recovery for dolphins crossing
through the HKLR alignment back to the baseline level. It also suggested that
the low level of north-south movement in recent years could be attributed by
two factors: (1) the physical presence of bridge piers and narrower spacing
between them which could partially obstruct dolphin movements; (2) The on-going
deterioration of habitat quality in North Lantau waters that makes it less
attractive for dolphins to cross the HKLR alignment from WL to NL waters (and
vice versa). However, it would be difficult to conclude which of the factors,
or both, has influenced the observed declining level of north-south movements
in recent years.
In order to understand the potential
impact of bored piling works of HKLR construction, another requirement of the
HZMB HKLR EM&A Programme was to investigate the dolphin acoustic behaviour
at and near the bored piling sites during pre-construction phase (January –
February 2013) and the initial phase of construction phase (March – July 2013).
This acoustic monitoring study revealed
that there were significant increases in the ambient noise levels that were
measured near bored piling pier sites during the construction phase, as
compared to the condition before construction. Moreover, dolphins’ occurrence
near construction area as well as their average whistling rate (utilized during
socializing activities) was substantially lower during the construction phase
than the pre-construction phase.
Significant decreases in both whistling
and clicking rates were also observed during the afternoon of the initial
construction phase, and the study suggested that such reduction may have occurred
in response to the increased noise level as contributed by HKLR construction
activities.
The study also suggested that the
dolphins which did occur in the area shifted their behavioural patterns,
perhaps spending less time socializing than during the pre-construction phase.
Furthermore, the higher clicking production rates by lone animal during the
initial construction phase indicated a higher level of alertness in response to
construction activities in the area.
As the noise contributed by bored piling
activities was a major concern to the dolphins at the EIA stage, another
important study conducted under the Tuen Mun – Chek Lap Kok Link (TMCLKL)
EM&A programme in relation to the overall HZMB construction works is also
considered here as useful reference. In this monitoring study, noise level was
measured at different distances from several bored piling sites of TMCLKL
alignment before and during the initial phase of the piling works in 2014.
The monitoring study found that in the
vicinity of the bored piling operations, there was an increase of approximately
11 dB between the baseline phase and construction phase. However, such increase was not strictly the
result of construction-related sounds emanating from the bored piling pier
locations, as the acoustic records and observation logs confirmed that the
soundscape was dominated by transient vessel noise in relation to the bored
piling operation. In fact, based on propagation modelling results from this
study, the transient noise likely masked the noise generated by the bored
piling works.
It should be mentioned that
coincidentally, both the acoustic behavioural study and passive acoustic
monitoring study on the dolphins found that there was a substantial reduction
in dolphin occurrence during the initial stage of bored piling works, as
compared to the pre-construction period.
Throughout the landscape establishment
period during the post-construction phase of HKLR Project, landscape
establishment monitoring was conducted by other parties for Contract No.
HY/2011/09 on 1 August 2019 (postponed from 31 July 2019 because of inclement
weather), 23 September 2019, 29 November 2019, 10 January 2020, 20 March 2020
and 11 & 22 May 2020. Monitoring results of different monitoring locations
are summarised below.
Portion A
Date |
Observation |
1 August
2019 |
Some
trees (Phoenix roebelenii) and shrubs (Rhododendron
pulchrum) at Portion A were observed to be in
poor health or dead. The Contractor was reminded to review the health of all
trees and shrubs and replace them if confirmed dead. |
23
September 2019 |
Some
trees (Phoenix roebelenii) and shrubs (Rhododendron
pulchrum) were observed to be in poor health or
dead. The Contractor was reminded to review the health of all trees and
shrubs and replace them if confirmed dead. |
29
November 2019 |
Some
trees (Phoenix roebelenii) and shrubs (Rhododendron
pulchrum) were observed to be in poor health or
dead. The Contractor was reminded to review the health of all trees and
shrubs and replace them if confirmed dead. |
10
January 2020 |
Some
trees (Phoenix roebelenii) and shrubs (Rhododendron
pulchrum) were observed to be in poor health or
dead. The Contractor was reminded to review the health of all trees and
shrubs and replace them if confirmed dead. |
20 March
2020 |
Some
trees (Phoenix roebelenii) and shrubs (Rhododendron
pulchrum) were observed to be in poor health or
dead. The Contractor was reminded to review the health of all trees and
shrubs and replace them if confirmed dead |
11 &
22 May 2020 |
No
observation |
Portion C
Date |
Observation |
1 August
2019 |
No
observation |
23
September 2019 |
No
observation |
29 November
2019 |
No
observation |
10
January 2020 |
Some
trees (Phoenix roebelenii) and shrubs (Rhododendron
pulchrum) were observed to be in poor health or
dead. The Contractor was reminded to review the health of all trees and
shrubs and replace them if confirmed dead. |
20 March
2020 |
Some
trees (Phoenix roebelenii) and shrubs (Rhododendron
pulchrum) were observed to be in poor health or
dead. The Contractor was reminded to review the health of all trees and
shrubs and replace them if confirmed dead |
11 &
22 May 2020 |
No
observation |
Viaduct
between P112 and P114
Date |
Observation |
1 August
2019 |
Weeds and
unwanted plants were observed at the planter area at the viaduct between P112
and P114. The Contractor was reminded to remove them and replant the approved
species for groundcover according to the approved plan. |
23
September 2019 |
Weeds and
unwanted plants were observed at the planter area. The Contractor was
reminded to remove them and replant the approved species for groundcover
according to the approved plan. |
29
November 2019 |
●
The groundcovers (Catharanthus roseus and Lantana montevidensis) were observed to be in poor health or
dead. The Contractor was reminded to review the health condition of all
groundcovers and re-planted if necessary.
●
Weeds and unwanted plants were observed. The Contractor was
reminded to remove them and replant the approved species for groundcovers
according to the approved plan. |
10
January 2020 |
●
The groundcovers (Catharanthus roseus and Lantana montevidensis) were observed to be in poor health or
dead. The Contractor was reminded to review the health condition of all
groundcovers and re-planted if necessary.
●
Weeds and unwanted plants were observed. The Contractor was
reminded to remove them and replant the approved species for groundcovers
according to the approved plan. |
20 March
2020 |
●
The groundcovers (Catharanthus roseus and Lantana montevidensis) were observed to be in poor health or
dead. The Contractor was reminded to review the health condition of all
groundcovers and re-planted if necessary. ●
Weeds and unwanted plants were observed. The Contractor was
reminded to remove them and replant the approved species for groundcovers
according to the approved plan. |
11 &
22 May 2020 |
●
The
groundcovers (Catharanthus roseus and Lantana montevidensis)
were observed to be in poor health or dead. The Contractor was reminded to
review the health condition of all groundcovers and re-planted if necessary. ●
Weeds
and unwanted plants were observed. The Contractor was reminded to remove them
and replant the approved species for groundcovers according to the approved
plan. |
Kwo Lo Wan Road
Date |
Observation |
1 August
2019 |
No
observation |
23
September 2019 |
No
observation |
29
November 2019 |
Some Phoenix
roebelenii were removed. The Contractor was
reminded to re-plant them according to the approved plan. |
10
January 2020 |
Some Phoenix
roebelenii were removed. The Contractor was
reminded to re-plant them according to the approved plan. |
20 March
2020 |
Some Phoenix
roebelenii were removed. The Contractor was
reminded to re-plant them according to the approved plan. |
11 &
22 May 2020 |
No
observation |
Airport
Road
Date |
Observation |
1 August
2019 |
Weeds and
unwanted plants were observed at the planter area at Airport Road. The
Contractor was reminded to remove them to ensure the healthy establishment of
the target species accordingly. |
23
September 2019 |
Weeds and
unwanted plants were observed at the planter area. The Contractor was
reminded to remove them to ensure the healthy establishment of the target
species accordingly. |
29
November 2019 |
Weeds and
unwanted plants were observed. In addition, the Phoenix roebelenii are also in poor health or dead. The Contractor
was reminded to remove the weeds and unwanted plants to ensure the healthy
establishment of the target species accordingly. |
10
January 2020 |
Weeds and
unwanted plants were observed. In addition, the Phoenix roebelenii are also in poor health or dead. The
Contractor was reminded to remove the weeds and unwanted plants to ensure the
healthy establishment of the target species accordingly. |
20 March
2020 |
Weeds and
unwanted plants were observed. In addition, the Phoenix roebelenii were also in poor health or dead. The
Contractor was reminded to remove the weeds and unwanted plants to ensure the
healthy establishment of the target species. |
11 &
22 May 2020 |
No
observation |
Based on the observations, the
Contractor was reminded to review the health condition of the plants, remove
weeds and replant approved plants as needed to meet the aim of the mitigation
measures proposed during EIA stage.
The landscape establishment monitoring
checklist for the last monitoring in May 2020, and the relevant monitoring
photos and locations of trees selected for monitoring are provided in Appendix C.
Viaduct
between P112 and P114
For the observations found in May 2020,
the Contractor completed rectification action with weeds removed and re-planted
approved plants for groundcovers according to the approved plan to meet the aim
of the mitigation measures. The relevant photos of rectification record in September
2020 are provided in Appendix C.
As this review report focus on the
surveys conducted in WL waters, the review of EIA predictions will only
concentrate on the potential impacts and associated mitigation measures in
relation to the open sea portion of the HKLR section as detailed in the EIA
report. This section of the 5.6 km viaduct is located between the connection
point with the HZMB Main Section at the western HKSAR boundary (situated at
about 4 km west of Sham Wat and 3 km north of Tai O Pier) and the western
opening of the airport channel near Sha Lo Wan.
Environmental impacts that are specific
to the CWD were identified in the EIA report, and the following is a summary of
predictions on the main impacts for construction and operation phases that were
assessed.
The marine section of HKLR is a viaduct
supported by piers, which has resulted in some physical loss of marine habitat
(seabed and water column) from construction works at locations where piers were
installed to support the bridge deck. In total, there were about 112 pier sites
in the open sea portion, and two piers were constructed side-by-side at each
pier site to support the bridge deck. The total permanent seabed loss due to
project footprint in the open sea portion of the marine section of HKLR was
estimated to be 2.24 hectares.
In addition to permanent habitat loss,
the works area in each pier site caused some additional temporary loss of
seabed and water column habitat during construction, which was estimated to be
5.6 hectares (but these marine habitats would not be disturbed all at the same
time as the piers were constructed in sequence, according to the EIA report).
As such habitat loss caused by the
bridge piers would be small and scattered, the EIA report considered the impact
on marine habitat loss to dolphins to be minor, and no mitigation measure was
required.
Major potential water quality impacts
that might arise during construction phase of the marine section of HKLR would
include pier site dredging, construction site runoff and wastewater from
construction activities as identified in the EIA report. Nevertheless, the
report assessed that the water quality impact was controlled as the pier site
construction would be in sequence and therefore the maximum number of pier
sites simultaneously under construction would be 35, while the pier locations
would also be enclosed by cofferdams and silt curtains. Moreover, the report
suggested that the western waters of Hong Kong are characterized by high
background levels of suspended solids while CWD are expected to adapt well in
an environment of high suspended solids.
Therefore, the EIA report predicted that
dolphins were not expected to be impacted by increase of suspended solids
caused by the HKLR construction works, with no mitigation measure being
proposed other than the implementation of silt curtain to control sediment
re-suspension and limiting the number of concurrent work fronts.
The main concern for construction noise
for the marine section of HKLR focused on noise from bored piling works, in
which much of the noise originated from the engine providing the power. Metal
cases for the piles were pushed into seabed sediment by machines rather than
driven by hammers during bored piling. Some noises associated with driving and
extraction of temporary casings would be produced, but at a much lower level
than percussive piling method as suggested by the EIA report. As there were 35
pier sites in the open sea portion and the bored piling works were scheduled to
be conducted in a limited number of site at any given time (17 or lower
according to the EIA report), the EIA report considered that marine noise
impact would be minimized.
The EIA report also identified vessel
noise as a potential disturbance factor for dolphins, although it suggested
that vessels associated with marine construction activities of HKLR would
produce mostly low-frequency noise below the sound that dolphin mainly
utilized. Therefore, these types of work vessels were not thought to be a
significant source of acoustic disturbance to dolphins.
Overall, as a precautionary approach,
marine noise impact was ranked as moderate in the EIA report. Several mitigation measures, including the
use of quiet vibratory piler, avoidance of drilling onto rock surface of bored
piles for the installation of the bored pile casing during May and June, and
implementation of dolphin exclusion zone, were proposed to reduce this impact.
Some underwater noise monitoring for the bored piling works was also conducted
during the construction phase to verify the predictions of the assessment.
Although vessel noise was not thought to
be a major source of acoustic disturbance to dolphins by the EIA report, they
might need to change their diving and surfacing patterns to avoid being hit by
large vessels. The report identified that such impact would result in
behavioural disturbance in areas with active marine construction.
Nevertheless, the EIA report also
suggested that most of the vessels being involved in the HKLR construction were
slow-moving working barges and vessels. Therefore, the marine traffic issue
would not likely to be critical, and such impact on dolphin was ranked as minor
to moderate, which was mitigated by setting up regular routes for vessels to
avoid dolphin hotspots, implementation of vessel speed limits of 10 knots, and
training for vessel captains.
During the operation phase, a major
concern was raised in the EIA report that the series of bridge piers could restrict
the movement of dolphins, as some individuals have been using both North and
West Lantau waters. If dolphins restricted their movements because of physical
structure of the HKLR viaduct alignment, this would be a significant impact as
that would affect their ability to forage and socializing with one
another.
The main concern would be on whether the
space between the bridge piers would constitute a restriction for dolphin movement
or discourage dolphins to pass through the space, and if the shade of the
viaduct on sea surface would affect them by avoiding to swim underneath the
bridge structure. Other examples of bridge structures outside of Hong Kong were
considered in the EIA report to provide evidences on the possible fragmentation
impact on dolphins.
After all considerations, the EIA report
predicted that the bridge structure would not cause a significant impact on
cetacean movements or distribution, and the dolphin monitoring programme was in
place to cover the movement ranges of individual dolphins, and to verify the
validity of such assessment.
The only development that had
significant overlap with the HKLR open sea portion in temporal and spatial perspectives
would be the Main Bridge section of HZMB in Guangdong waters, as one of the two
artificial islands connecting the underwater tunnel section was directly linked
to the HKLR at the western boundary of Hong Kong territorial waters. Such
reclamation works for the artificial islands commenced in 2010 for completion
in 2014 according to the EIA report, and this overlapped with the baseline and
initial construction periods of the HKLR.
The EIA report assessed that this
concurrent project (reclamation of artificial islands) would involve dredging
and filling works, and would have the potential to produce cumulative water
quality impact including increased level in suspended solids at dolphin
hotspots during construction phase. Even though construction of the Main Bridge
would involve bored piling works, there was sufficient separation of the bored
piling activities between the two project sites (at least 6.7 km apart), while
the magnitude of any cumulative marine traffic disturbance impact was assessed
to be low.
Furthermore, reclamation for the two
artificial islands as part of the HZMB Main Bridge would cause 80 hectares of
marine habitat loss, but such loss was considered insignificant in comparison
to the extensive range of marine habitat within the Mainland waters in the
Pearl River Delta. In view of the severity of the impacts, the EIA report
concluded that further mitigation measures would not be needed for these
cumulative impacts.
It should be mentioned that the EIA
report listed a few potential positive effects during the operation phase of
HKLR. After the opening of HZMB, it was expected a decreased demand on marine
traffic between Hong Kong and Mainland, which would reduce the risk of dolphins
colliding with marine vessels, especially in area with high abundance.
There would also be another potential
enhancement effect of the bridge piers, as the piles supporting emerged pile
caps could greatly increase the amount of hard-surface habitat and provide
opportunities for fouling organisms to settle and develop, which in turn would
attract scavengers and small predators and provide food resources of higher
predators such as dolphins.
Vessel-based line-transect monitoring
Dolphin occurrence was at the lowest
level during the post-construction monitoring period, and there was a
continuous and significant declining trend in dolphin abundance during the
nine-year dolphin monitoring programme in WL. More specifically, the decline in
dolphin usage was mainly at the northern portion of WL survey area, which
overlapped with the HKLR alignment. The majority of assessed individual
dolphins have avoided the HKLR alignment, which might have also limited or
hindered the north-south movement of many individuals across the bridge
alignment.
Land-based study on north-south
movements
The north-south movements of dolphin
groups in WL waters remained at a very low level in the past several years,
without any sign of recovery for dolphins crossing through the bridge alignment
back to the baseline level.
Acoustic behaviour monitoring
Dolphins occurred in the construction
area have shifted their behavioural patterns, spending less time socializing at
the initial stage of construction than during the baseline phase. Dolphins also
had a higher level of alertness in response to construction activities in the
area by increasing their clicking production rates.
Underwater
noise monitoring
In the vicinity of the bored piling
operations, there was a noticeable increase in underwater noise, which was
mainly contributed by the transient vessel noise rather than the bored piling
noise. Coincidentally, there was a substantial reduction in dolphin occurrence
during the bored piling works with the elevated noise level.
In contrary to the EIA predictions that
the HKLR construction would not cause significant impact to dolphins in WL
waters with sufficient mitigation measures in place, their occurrence has been
on a significant decline during the construction phase, and there has been no
sign of recovery during the post-construction phase.
In addition to the vessel-based
monitoring programme, several supplementary studies were conducted to verify
the predictions made in the EIA report. Those studies concluded that the
north-south movements of individual dolphins remained at a low level after the
HKLR bridge piers were set up, and there was no sign of recovery of such
movement at this point, which also concurred with the findings from the
vessel-based monitoring programme.
Moreover, at the initial stage of HKLR
construction, the ambient underwater noise was significantly higher near bored
piling sites, and it appeared that dolphins were affected by shifting their
acoustic behavioural patterns near the work area. Another study completed under
TMCLKL EM&A programme also demonstrated that there was a noticeable
increase in underwater noise during bored piling operations, which was mainly
contributed by the transient vessel noise associated with the marine works,
with substantial reduction in dolphin occurrence with the elevated noise level.
There are several plausible explanations
behind the discrepancies between the EIA predictions and the actual outcome of
the CWD monitoring results for the HKLR EM&A programme.
It is apparent that the EIA report has
underestimated the magnitude of some of its predictions for some temporary
impacts on dolphins. For example, the marine noise associated with the bored
piling works was significantly higher. Even though the bored piling procedure
itself might not cause too much noise, the associated transient noise of moving
vessels near the bored piling works (such as the ones transporting workers to
and from work barges) was the likely source that had primarily contributed to
the elevated noise level. This would in turn affect the dolphin acoustic
behaviour and deter them to move away from the work sites. Such impact would
certainly cause some temporary displacements of dolphins from their favourable
habitat during the marine construction works.
Also, the EIA report has predicted that vessels
involved in the HKLR construction works would mostly be slow-moving and emit
low-frequency marine noise that would not affect dolphins. However, it has been
frequently observed from land (during the shore-based theodolite tracking on
north-south movements) and boat (during vessel surveys and acoustic monitoring
surveys) that there were large number of work boats (mostly transportation
boats shuttling workers to and from various marine work fronts) within the HKLR
construction area. As a result, dolphins might have to shift their acoustic
behavioural patterns in response, as suggested by the acoustic monitoring study
at the early stage of construction works. Similar to marine noise impact, such
intense and fast-moving marine traffic would also cause some temporary
displacements of dolphins from their favourable habitat, at least in the
northern portion of the WL survey area that overlapped with the HKLR marine
works.
Due to the underestimation of
construction impact, the mitigation measures suggested by the EIA report and
adopted during construction to minimize the impact of noise and marine traffic
have not been as effective as originally predicted, which is evidenced by the
noticeable decline in dolphin occurrence in WL waters throughout the construction
phase monitoring.
Nevertheless, even though the
abovementioned impacts might have resulted in decline of dolphin occurrence in
WL waters during the marine construction works of HKLR, these impacts should be
temporary in nature, and one would have assumed that these impacts would only
affect dolphins during the construction phase.
Once the construction is completed and the marine traffic with
associated noise have subsided, it would be a reasonable assumption that
dolphins would return to WL waters (especially to the northern portion of the
survey area where the marine construction works took place), and the level of
dolphin occurrence would return back to the baseline level. However, as
observed in the post-construction monitoring results, there has been no sign of
such recovery. In fact, dolphin abundance has continued to fall to the lowest
level in 2018 – 2020 during post-construction phase. Therefore, the logical
assumption is that either the operation impacts arising from the bridge
construction have also been underestimated, or additional anthropogenic impacts
from other projects have resulted in the lower occurrence of dolphins at the
end of the post-construction monitoring.
The habitat loss caused by the marine
bridge piers was predicted to be small and scattered, and therefore such impact
was considered as minor in the EIA report with no mitigation measure
needed. However, the presence of the
bridge piers had likely affected dolphins more by limiting their north-south
movements between North and West Lantau waters, which would ultimately affect
dolphin usage in West Lantau waters. The land-based monitoring on north-south
movement of dolphins concluded that such level of movements remained low in the
past few years, though the original intention of this monitoring requirement
was to verify the validity of the EIA assessment that the bridge structure
would not cause a significant impact, as such assessment was difficult to
substantiate at that time.
In fact, there have been several lines
of evidences that such limitation of north-south movements and reduced dolphin
usage in West Lantau waters have already occurred in recent years. Firstly, the
post-construction monitoring surveys showed that dolphin usage was lower in the
northern portion of WL survey area when compared to the baseline condition. The
surveys also showed that many individual dolphins have avoided the bridge
alignment in the past two years, and the bridge might have limited or hindered
the north-south movement of most of the individuals. Secondly, the shore-based
theodolite tracking provided direct evidence that the north-south movements of
dolphin groups remained at a very low level in the past several years with no
sign of recovery.
Furthermore, the AFCD long-term marine
mammal monitoring study revealed that many individual dolphins have shifted
their range use away from North Lantau to West Lantau waters, with very little
movement back to North Lantau thereafter (Hung 2019 and 2020). The same study
also showed that there was a large and significant decline in dolphin abundance
in North Lantau, from 50 dolphins estimated in 2011 (equivalent to the baseline
stage of HKLR construction) to only four dolphins estimated in 2019 (equivalent
to the post-construction stage of HKLR construction) (Hung 2020), and such
decline also coincided with the temporal changes in individual range use as
mentioned above.
While WL waters remained the area with
the highest dolphin density in Hong Kong with several important dolphin
habitats consistently recorded high level of use over the years (see Hung 2019
and 2020), it is evident that dolphin occurrence in the northern portion of WL
survey area has largely diminished, and this area is exactly where the bridge
construction occurred and the physical structure of bridge piers are
permanently present. Until there is clear evidence that the north-south
movement of dolphins across the bridge alignment has resumed to the baseline
level, the impact of the bridge piers to such movements should be regarded as
significant and long-lasting, contrary to the prediction made in the EIA
report.
Finally, it should be mentioned that
habitat degradation in North Lantau waters in the past decade could contribute
further to the limitation of north-south movement of dolphins moving back and
forth between North and West Lantau waters, which in turn might have resulted
in the decline in dolphin usage in WL waters during and after HKLR
construction. In the past decades, there was a continuous decline in dolphin
abundance in North Lantau, which could be attributed to the increase in
high-speed ferry traffic from the Sky Pier (see Marcotte et al. 2015), the
reclamation works for HKBCF and HKLR as well as the recent massive reclamation
works for the third runway expansion for the Hong Kong International Airport.
It is clear that the North Lantau was once an important habitat for dolphins
with their widespread usage of the area (see Hung 2008), but nowadays the
waters to the north of Lung Kwu Chau is the only
remaining area utilized by dolphins on a regular basis, albeit at a much lower
level in recent years (see Hung 2019 and 2020).
Notably, the 650 hectares of dolphin
habitat loss as a result of the massive reclamation in relation to the third
runway expansion was not included in the HKLR EIA report for its cumulative
impact assessment, but such habitat loss has clearly contributed to the further
decline in dolphin occurrence in North Lantau since the project commencement in
2016. The large-scale habitat loss from this infrastructure project is only
situated a few kilometers to the north of HKLR bridge
alignment, and at an area where individual dolphins have utilized as the main
travelling corridor to move between Sha Chau and Lung Kwu
Chau Marine Park and the West Lantau waters (Hung 2013). This would directly
affect the north-south movement of dolphins across the bridge alignment, and
result in their reduced usage of WL waters in recent years.
The EM&A programme requires
post-construction phase monitoring for CWD and landscape establishment
monitoring works. Weather conditions in the post-construction monitoring months
are provided in Appendix D. All monitoring
works were conducted as scheduled. The overall performance of the monitoring
methodology adopted in this Assignment was deemed effective.
This Final EM&A Review Report
presents the post-construction environmental monitoring works undertaken in the
period between November 2018 and October 2020. All marine-based construction
activities have been completed. The landscape establishment monitoring has been
conducted bi-monthly and completed to ensure the aims of the landscape and
visual mitigation measures proposed during EIA stage are met.
The post-construction dolphin monitoring
works in WL waters have been completed in October 2020, with the results being
assessed in comparison with the baseline and construction phase monitoring data
collected before and during the HKLR construction. The baseline, construction
phase and post-construction phase dolphin monitoring as well as several
supplementary studies completed under the HKLR EM&A programme provided
valuable information for the evaluation on the predictions of impact assessment
during the EIA stage, as well as the adequacy and effectiveness of suggested
mitigation measures. Important lessons can be learnt from such comprehensive
monitoring programme for future EIA studies and EM&A programmes in Hong
Kong, especially the ones within marine mammal habitats.
Nevertheless, it may take a long period
of time for recovery in dolphin usage in WL waters to review the overall
impacts on dolphins from the HKLR construction with other cumulative impacts.
It would be useful to study the level of north-south movement of dolphins across
the bridge alignment by shore-based theodolite tracking work in the future to
determine recovery in dolphin usage from the effect of the HKLR operation.
The overall EM&A programme to
examine the potential impacts of HKLR and evaluate the predictions of the EIA
report has provided solid proof that it has been working well according to the
intention of the EIA framework in Hong Kong. Important findings of this
EM&A programme could be taken to fill information gap and facilitate
further monitoring works, as well as to improve the impact predictions and
associated mitigation measures for future infrastructure project. This review report would also provide a good
example of how EIA studies should be routinely reviewed in the future.