Irish mapping agencies Office of Public Works OPW
Irish mapping agencies Office of Public Works (OPW) are the state agency in Ireland tasked with management of physical Irish coast line and coastal defences (20 -30 staff) Ordnance Survey Ireland (OSi) are the semi-state agency in Ireland tasked with management of onshore topographic mapping (140 -170 staff) Geological Survey Ireland (GSi) are the state agency in Ireland tasked with mapping of onshore/offshore geological mapping (50 -80 staff)
Phase 2 – Coastal DTM’s • Inclusion of high resolution coastal DTM’s • The coastal DTM will extend up to at least Highest Astronomical Tide -to 12 nm offshore E. g. Bantry Dunmanus
Bantry & Dunmanus Bay Co Cork (2006)
Vessel bathymetry Water column penetrating Marine LIDAR
Drawbacks of Marine LIDAR usage: - Turbidity (clarity of water) - Contact resolution (1 m x 1 m dot density ideal) - Cost (generally a factor of 5 increase as against onshore LIDAR) - Increased post-processing capacity required SHALLOW WATER VERY TURBID WATER
Water column penetrating Marine LIDAR Surveys in Ireland 2003 - Survey of part of Killala Bay for GSI / Moy Valley Company 2002 - Clew Bay – Initial trial for the Geological Survey of Ireland (GSI) 2003 - Clew Bay Completion of the Clew Bay Survey for GSI 2006 – Bantry Bay, Dunmanus Bay, South Galway Bay 2005 - Mulroy Bay survey for GSI / County Donegal. 2008 - BLOM survey for GSI of Donegal/Sligo/ Gretamans Bays TENIX survey of Tralee/Blacksod/ Foyle Bays 2010 - Pelydryn survey for GSI of Inner Mulroy/ Killala/Sligo/ Lough Swilly/Galway Bays
Satellite bathymetry
Satellite mapping! 2012 test area in Wexford PROTEUS Ltd World. View-2 Satellite Map of Wexford Harbour derived from satellite Imagery. 0 -10 m Useful overview but not accurate enough (2 m x 2 m) for shipping safety
Drawbacks of Satellite usage: - Turbidity (clarity of water) - Cloud (needs clear skies) - Contact resolution (2 m x 2 m dot density ideal) - Cost (generally a factor of 2 -3 increase on equivalent ship cost) - Increased post-processing capacity required
Vessel acquisition versus Satellite acquisition in the Shannon Estuary 2013 campaign of 5 bays acquisition Proposed Irish bays for satellite data acquisition
Office of Public Works (OPW) Topographic coastal LIDAR Surveys in Ireland - The best topographic coastal LIDAR flying dates are on the days of spring tide. - The OPW LIDAR data flown in the coastal regions of Ireland are seeking coverage out to mid tide only. - There are flown with the expressed end usage of managing coastal defences LIDAR
Office of Public Works (OPW) Topographic coastal LIDAR Surveys in Ireland OPW Coastal Topo Lidar coverage
Topographic LIDAR potential for coastal Ireland
Topographic onshore LIDAR Surveys in Ireland flown by OSi All Osi Topo Lidar flown to High Water Mark (HWM)
Topographic coastal LIDAR Surveys in Ireland flown by OSi - The best terrestrial LIDAR flying dates are on the days of spring tide. - Terrestrial LIDAR has no water penetration capability. - The spring tide day usually occurs a day or two after both the full moon and then the new moon days of any calendar month. - There are usually 2 spring tides in a calendar month. - Flying to capture the low tide mark is only optimum for one (1) hour either side of the low water time on those spring tide days.
GSI Vessel bathymetry mapping!
Dublin Bay survey approach
Vessel costs: Medium water vessels € 14, 000 per day Medium to shallow vessels € 7000 per day Shallow water vessels € 3000 per day Topographic LIDAR costs: Survey mobilisation € 25 k - € 50 k Per bay cost --- complex € 100 k least complex € 20 k Marine LIDAR costs: Survey mobilisation € 250 k Per bay cost --- complex € 500 k least complex € 100 k Satellite costs: Survey mobilisation 50% of contract price Per bay cost --- complex € 50 k least complex € 20 k
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