Introduction
This is a comment on
Draft Hoi Ha Outline Zoning (OZP) Plan No. S/NE-HH/1.
Background
When Hoi Ha Wan SSSI and Marine Park were
being established, only two threats significant enough to cause irreparable
damage the coral communities in Hoi Ha Wan were identified. These are pollution
and sediment runoff from future development in the area, yet neither of these
risks have been considered in the Draft OZP.
Geologic continuum
Hoi Ha Wan lies at the end of a geologic
continuum, which starts in the hills above Hoi Ha and passes directly through
Hoi Ha village into Hoi Ha Wan. This continuum comprises a simple cycle of
uplift, erosion and deposition. In this continuum, Hoi Ha village is an area of
deposition and the coral communities lie at its end.
Disruption
of geologic continuum and threats of sedimentation
Development of village houses in the area will
require excavation and exposure of the topsoil and underlying sediments,
causing a disruption to this continuum. Because of the underlying geology, a
landslide hazard has been identified as a Geotechnical Constraint in the area,
but the Geological Constraints associated with this have not been considered.
Because Hong Kong is naturally subject to
heavy downpours of rain and extreme weather events, the excavation and exposure
of topsoil and sediment in the area could lead to a massive single discharge of
sediment or prolonged discharges of sediment into Hoi Ha Wan, smothering the
coral communities, leading to their degradation or in a worst case scenario,
resulting in their total destruction.
Hoi Ha Wan has a history of this. In the
1980’s, the loss of a coral community was recorded on the eastern shore of Hoi
Ha Wan because of soil and sand runoff, when trees and rocks were removed from the
surrounding hills for reclamation of land at the Ma On Shan new town1.
In fact, this incident represents a classic case study to show what can go
wrong if attention is not paid to the risks associated with disrupting a
geologic continuum.
Comment
If, as stated in the Draft Hoi Ha OZP there is
a need to conserve the areas of conservation value and protect the ecological
significance of the area, no discussion can take place without making reference
to the risks associated with disrupting the geological continuum in the area, meaning
that the threats posed to the coral communities from sediment inundation have
not been considered or addressed.
Reference
1 LAM, K Y, SHIN, P K S, BRADBEER, R S, KU, K K K , HODGSON, P A and CHEUNG, S G,
"Baseline Data of Subtropical Coral Communities in Hoi Ha Wan Marine Park,
Hong Kong, Obtained by an Underwater Remote Operated Vehicle (ROV)", Marine
Pollution Bulletin, Vol 54, January 2007, pp 107-112.
Petition
If you want to object to the proposed development in Hoi Ha,
please sign the petition here:
No comments:
Post a Comment