Cove Sailing Club in Conjunction with Cork County Council Whitepoint Marina Flow Regime Impact Hypothesis - IRELAND UK UAE BAHRAIN
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Cove Sailing Club in Conjunction with Cork County
Council
Whitepoint Marina
Flow Regime Impact Hypothesis
Report No. CM1199_MA_R0404
March 2019
Revision 0
IRELAND • UK • UAE • BAHRAIN
Document Control
Document: Flow Regime Impact Hypothesis
Project: Whitepoint Marina
Client: Cove Sailing Club in Conjunction with Cork County
Council
Report Number: CM1199_MA_R0404
File Origin: Z:\PROJECTS 2019\CM1199 Whitepoint Marina Phase 1\5
BLP Reports\02 Planning
Application\CM1199_MA_R0404_00 Flow Regime Impact
Hypothesis.docx
Document Checking:
Authorised
Revision /
Revision Details of Issue Checked
Review Date
Prepared By Approved By
By
07-March-
0 Issued for Planning PM SMC AC
2019
Disclaimer: Please note that this report is based on specific information, instructions and information from our Client
and should not be relied upon by third parties.
3 Westbourne Place, Cobh, Cork, P24 Y560 Ireland
Tel: +353 (0) 21 4815441, e-mail: Cobh@ByrneLooby.com
www.ByrneLooby.com
i
ByrneLooby www.ByrneLooby.com March 2019 Rev 0Contents
1 Introduction ............................................................................................................ 1
1.1 Existing Hydrodynamic Regime .......................................................................... 1
2 Proposed Development ............................................................................................ 2
3 Assessment of Changes of Flow Regime .................................................................... 3
3.1 Flow Changes due to Marina Development ......................................................... 3
3.2 Impacts due to Vessel Activity ............................................................................ 3
4 Impacts to Cruise Liner Berth .................................................................................... 4
5 References ............................................................................................................. 4
Appendix 1 – Harbour Channel Plan & Cross-Section .................................................... A
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1 Introduction
The proposed development consists of the construction of a 25 berth marina, access walkway
and associated marine and landside infrastructure at Whitepoint, Cobh, Co. Cork.
1.1 Existing Hydrodynamic Regime
The largest currents created within Cork Harbour are tidal currents and river flow currents.
Wave induced currents are of small magnitude as the wave conditions are of a small scale.
Sediment transport patterns are generally comparable with tidal and river flow patterns.
Deposition occurs in areas of low flow with erosion occurring in areas of high flow.
Developments that may impact on flow regimes and subsequently sediment transport patterns
include dredging and the construction of piers, jetties, breakwaters etc. Marina infrastructure
(pontoons, floating breakwaters, chains, piles, anchor blocks) generally does not have a
significant effect on flow regime and sediment transport.
Sediment transport can be caused by waves, wind or river flow. Transport is caused by the
shear stresses of the moving water or wind acting on particles.
The theoretical basis for sediment transport in water bodies along shorelines and offshore is
not fully developed. This is largely because at the present time we do not have a complete
understanding of sediment transport even under simpler conditions, such as uni-directional
sediment transport in rivers and channels, despite the efforts of many investigators over the last
century to put forward theories to understand it. For example, estimates of the sediment
discharge of a river using different theories can differ by several orders of magnitude. (Dean &
Dalrymple, 2002).
Wind generated sediment transport is not examined at this site as the sea bed is covered by
water at all times under the footprint of the marina.
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ByrneLooby www.ByrneLooby.com March 2019 Rev 0Flow Regime Impact Hypothesis
Report No. CM1199_MA_R0404
2 Proposed Development
The proposed marina development will include the installation of floating pontoons and
breakwater units, anchor blocks and anchor chain connecting the pontoons to the anchor
blocks. The breakwater units will have a draught of 1.3m, and the pontoon units will have a
draught of 0.5m. Anchor chains will connect the pontoons to anchor blocks which will sit on,
and overtime partially settle into the sea bed. The anchor chains would have a negligible
effect on flow regime and sediment movement as they are of very low cross sectional area.
The anchor blocks would have a negligible effect on flow regime and sediment movement as
they are of small scale and will partially settle into the sea bed sediment after a number of
months.
The site of the proposed marina is in the lee of Whitepoint, where natural deposition occurs
due to the bathymetry of the river channel and the net downstream migration of sediments.
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Report No. CM1199_MA_R0404
3 Assessment of Changes of Flow Regime
3.1 Flow Changes due to Marina Development
Appendix 1 shows a plan of the proposed marina and the river area. The settlement of
sediments is a function of river flow velocity and channel cross sectional area (For open
channel flow scenarios).
A representative cross section drawn through the river channel from the proposed marina to
Haulbowline Island (see Appendix 1) yields a cross sectional water area of 7731m² at mean
high water spring tides (MHWS) and 6684m² at mean low water springs tides (MLWS). The
cross-sectional area of the proposed marina infrastructure (pontoons, chains, anchors etc.) is
approximately 970m². This represents a decrease in the channel cross sectional water area of
11% to 12%, depending on tide levels. It is estimated that the marina development will
increase the flow velocity in the area by approximately 0.5% to 0.7%, due to the reduction in
river cross sectional area, which represents a flow increase of approximately 0.0075m/s to
0.0090m/s. This is a very small increase in the flow rate within the channel and it is therefore
estimated that sediment movements within the area will not be significantly affected. Some
localised currents would be generated around the corners of the floating units; however, these
currents would diminish in a very short distance from the units (i.e. less than 10m).
Any advanced sedimentation or hydrodynamic study would refine the assessment figures,
however, as the impacts are negligible, the final conclusion would be the same. In our
professional opinion, a full hydrodynamic study is not required.
3.2 Impacts due to Vessel Activity
It is highly unlikely that any scour due to the rotation of vessel propellers will occur at the
marina due to the deep water conditions. Also, the craft operating within the marina will be of
low power, operating at low speeds. Boats already operate within the footprint of the
proposed marina, at the swing mooring field, so the net affect can be deemed negligible.
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Report No. CM1199_MA_R0404
4 Impacts to Cruise Liner Berth
Based on our assessment of potential impacts to the river flow regime and changes to
sedimentation actions, outlined above, it is our opinion that the development of the proposed
marina will not have any impact on the cruise liner berth.
5 References
Coastal Processes with Engineering Applications
Robert G. Dean & Robert A. Dalrymple
Cambridge University Press
UK, 2002
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Report No. CM1199_MA_R0404
Appendix 1 – Harbour Channel Plan & Cross-
Section
A
ByrneLooby www.ByrneLooby.com March 2019 Rev 0NOTES;
1. DO NOT SCALE OFF DRAWINGS.
2. DIMENSIONS IN MILLIMETRES UNLESS NOTED
OTHERWISE. LEVELS IN METRES RELATIVE TO SITE
W DATUM.
E
3. ALL DIMENSIONS TO BE CHECKED ON SITE.
4. THIS DRAWING IS TO BE READ IN CONJUNCTION WITH
S ALL OTHER DRAWINGS & DOCUMENTS.
5. SEABED CONTOURS TO LOCAL CHART DATUM.
66100 N
LEGEND;
PLANNING BOUNDARY UNDER THIS APPLICATION
Existing Fixed Platform Structure SITE NOTICES
Granted Under Planning No. 10/52015 Existing Fixed Platform Structure Granted Under
A Port of Cork Mooring Buoys Planning No. 10/52015
C
Proposed Gangway
nd
grou
Play
Proposed Landing
Pontoon
B
A1
Footbridge
A2
Planning Boundary
B1
Site Notice A
B B2
Proposed Floating
Proposed 25No. Breakwater
DEVELOPMENT ADDRESS:
Berth Marina WHITEPOINT,
COBH,
CO. CORK.
PLANNING AREA = 1.3 Hectares
MAP SERIES :
1 : 2,500
6472-09
Revision Date = 14 December 2003
Survey Date = 31 December 1973
Levelled Date = 31 December 1985
01 07/03 PART 8 PLANNING APPLICATION TJOC PM AC
00 01/03 DRAFT FOR CLIENT REVIEW TJOC PM AC
Stn.W2
178511.28E
65757.61N
www.ByrneLooby.com
IRELAND UK UNITED ARAB EMIRATES BAHRAIN
Cove Sailing Club in
Conjunction with Cork County Council
Whitepoint Marina Development
Location Map (Scale 1:2,500)
Marina Flow Impact
C Harbour Channel Plan & Cross-Section
Planning Boundary Haulbowline
Planning Boundary Existing Sea Bed Naval Base
+5.90mCD
MHWS +4.11m
MHWN +3.25m
MLWN +1.35m
Planning Application
MLWS +0.45m
14/02/19 1:2,500 TJOC PM AC
Cross Section and Harbour Channel (Scale 1:2,000) Ordnance Survey Ireland Licence No. EN 0061919
© Ordnance Survey Ireland/Government of Ireland CM1199 CM1199_MA_0409_DWG_ 013 Westbourne Place, Cobh, Cork, P24 Y560 Ireland
Phone: +353 (0) 21 4815441
Email: Cobh@ByrneLooby.com | Web: www.ByrneLooby.com
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