At the Crossroads: Seamless At the Crossroads: Seamless Coastal Terrain Models in Coastal Terrain Models in

the Pacific Regionthe Pacific Region

Salesh Kumar and Jens KrugerSalesh Kumar and Jens Kruger

Ocean and Islands ProgrammeOcean and Islands Programme

Pacific Islands Applied Geoscience CommissionPacific Islands Applied Geoscience Commission

SOPAC

39th ANNUAL SESSION

STR“Map Once – Use Many Ways”

Presentation outlinePresentation outline

Coastal Terrain Modelling (CTM)Coastal Terrain Modelling (CTM) Brief description of MBES and LiDAR Brief description of MBES and LiDAR

systemssystems Compare 2 specific countries in the Pacific: Compare 2 specific countries in the Pacific:

Saipan (CNMI) and Funafuti (TUVALU) and Saipan (CNMI) and Funafuti (TUVALU) and the data available for these countriesthe data available for these countries

Look at the costs involved in both these Look at the costs involved in both these types of surveytypes of survey

ConclusionConclusion

Seamless CTMSeamless CTM

Coastal environment is a complex transitional system between theCoastal environment is a complex transitional system between the

terrestrial and marine realms. terrestrial and marine realms.

The coastal zone is a Constantly changing environment. TheThe coastal zone is a Constantly changing environment. The

awareness of the issues associated with the coastal zone and theawareness of the issues associated with the coastal zone and the

need to deal with them in an integrated way, are becoming more need to deal with them in an integrated way, are becoming more

prominent in coastal studies.prominent in coastal studies.

The ability to seamlessly map topography and bathymetryThe ability to seamlessly map topography and bathymetry is especially valuable for:is especially valuable for:

Studies examining or modelling coastal patterns and processes, Studies examining or modelling coastal patterns and processes, since many important marine habitats are emergent at low tides since many important marine habitats are emergent at low tides (e.g., intertidal seagrass, salt marshes, mangroves and (e.g., intertidal seagrass, salt marshes, mangroves and some coral reefs).some coral reefs).

Surveying the coastline is multidisciplinary since it involves both Surveying the coastline is multidisciplinary since it involves both land (topographic data) and water (hydrographic data).land (topographic data) and water (hydrographic data).

Many Pacific Island Countries (PIC’s) have bathymetry data up Many Pacific Island Countries (PIC’s) have bathymetry data up to 50mto 50m

Bathymetry data in areas shallower than 50 m do exist in some Bathymetry data in areas shallower than 50 m do exist in some PIC’s (mostly singlebeam data)PIC’s (mostly singlebeam data)

Satellite data can be used to extract bathy data in shallow Satellite data can be used to extract bathy data in shallow areas. (not done extensively at the moment)areas. (not done extensively at the moment)

Critical gap exists between the Topography and hydrography Critical gap exists between the Topography and hydrography data in most PIC’s.data in most PIC’s.

Teara.gov.nz

Factors that are driving the need for new data in Factors that are driving the need for new data in coastal zonecoastal zone

1.1. Urban expansion in the coastal zone – Waterfront buildings, Urban expansion in the coastal zone – Waterfront buildings, roads, bridges, harbours.roads, bridges, harbours.

2. Tourism – leisure boat traffic, sandy beaches, diving areas.2. Tourism – leisure boat traffic, sandy beaches, diving areas.

3. Oil and gas exploration – oil and gas pipe lines.3. Oil and gas exploration – oil and gas pipe lines.

4. Environmental surveying – shore erosion models, water flow 4. Environmental surveying – shore erosion models, water flow currents, sea floor vegetation.currents, sea floor vegetation.

5. Natural catastrophes mitigation – mitigation of effects of 5. Natural catastrophes mitigation – mitigation of effects of tsunamis, hurricane.tsunamis, hurricane.

6. Inland surveys - Wetlands, channels, large lakes6. Inland surveys - Wetlands, channels, large lakes

LiDAR Overview•Data Collection - Plane Equipped with GPS, INS & LiDAR• LiDAR sensor works day or night, cloud coverage or not•Collection of 3D points•Laser sent out from Emitter, reflects off terrain, Returns to Receiver - Receiver measures back scattered electromagnetic radiation (laser intensity)•Time difference determines range to target.

.

What Data is Collected During a Flight?“Everything”• Foliage, Bare Earth• Transmission Lines and Towers• Railway Beds,Roadways,Vehicles• Buildings,etc.Optional• Photography• Weather Conditions Oceanservice.noaa.gov

Limitations of ship based MBES for data collection in Limitations of ship based MBES for data collection in shallow water environments;shallow water environments;

• Navigation dangers and challengers posed to vessels Navigation dangers and challengers posed to vessels performing survey workperforming survey work

• The inability to collect data in water shallower than The inability to collect data in water shallower than approximately15mapproximately15m

• Reduced efficiencies due to the proportional relationship Reduced efficiencies due to the proportional relationship between water depth and bottom coveragebetween water depth and bottom coverage

Banic & Cunningham (1998) Guenther et al. (2000)

Advantages of LiDAR systems for mapping shallow water environments

• Negligible navigational risks when conducting shallow water Negligible navigational risks when conducting shallow water surveyssurveys

• Greater survey efficiencies in shallow-waters, as LiDAR swath Greater survey efficiencies in shallow-waters, as LiDAR swath width is independent of depth.width is independent of depth.

• Ability to collect seamless, coastal topographic-bathymetric Ability to collect seamless, coastal topographic-bathymetric (i.e., land and sea) datasets.(i.e., land and sea) datasets.

• For tidal zone, this is crucial as usually only short tide windows For tidal zone, this is crucial as usually only short tide windows are available for operations.are available for operations.

• The rate of coverage is very high, thanks to high sensing The rate of coverage is very high, thanks to high sensing frequency, typically about 20km2 and over 50km2 per hour or frequency, typically about 20km2 and over 50km2 per hour or more for hydrographic and topographic modes, respectively.more for hydrographic and topographic modes, respectively.

• Major advantages are fixed width (not dependent on water Major advantages are fixed width (not dependent on water depth), rapid transit to and conduct surveys, and cost efficiency depth), rapid transit to and conduct surveys, and cost efficiency compared to traditional techniques.compared to traditional techniques.

Combined datasets(Funafuti_Tuvalu)

•MBES data•Single beam data•Topography data

Multibeam data_offshore

Multibeam data_lagoon

Single beam dataTopo data

Bathy LiDAR, Saipan

Bathymetry LiDAR, Saipan

Topography LiDAR, Saipan

Combined Data sets

Topo & Bathy

Combined data: Topography and Bathymetry

Field surveys costs in FunafutiField surveys costs in Funafuti

Survey Survey Cost $AUDCost $AUD

Bathymetry survey pilot dredge site 1992Bathymetry survey pilot dredge site 1992 ~$20, 000~$20, 000

Bathymetry of pilot project dredge site 1995 Bathymetry of pilot project dredge site 1995 ~$20, 000~$20, 000

Multibeam bathymetry survey 2004Multibeam bathymetry survey 2004 ~$107,000~$107,000

Topographic survey 2009Topographic survey 2009 $135, 072$135, 072

Single beam bathymetry survey 2009Single beam bathymetry survey 2009 $99, 954$99, 954

TOTALTOTAL $375, 087$375, 087

LiDAR survey quote (LiDAR survey quote (Fugro Spatial Solutions PTY LTDFugro Spatial Solutions PTY LTD))

5 x 5 m bathy and Topo LiDAR5 x 5 m bathy and Topo LiDAR ~$365 000 to 445 000~$365 000 to 445 000

ConclusionConclusion

Offshore, ship based Multi-Beam Echo Sounder (MBES) survey Offshore, ship based Multi-Beam Echo Sounder (MBES) survey has matured, and the costs decrease as the technology has matured, and the costs decrease as the technology develops. However ship based MBES survey efficiency is develops. However ship based MBES survey efficiency is poor in complex shallow waters. The cost of multi beam poor in complex shallow waters. The cost of multi beam surveys increase dramatically as the depth decreases, and surveys increase dramatically as the depth decreases, and thus the MBES Swath width decreases.thus the MBES Swath width decreases.

Airborne Laser bathymetry Systems (ALBS) have, during the Airborne Laser bathymetry Systems (ALBS) have, during the last 10 years, proved their ability to survey large shallow last 10 years, proved their ability to survey large shallow areas quickly and accurately, fulfilling the requirements set areas quickly and accurately, fulfilling the requirements set by the International Hydrographic Organisation ( for IHO) by the International Hydrographic Organisation ( for IHO) for production of depth sounding data for charting for production of depth sounding data for charting purposes.purposes.

LiDAR bathymetry is a cost-efficient method which houses a LiDAR bathymetry is a cost-efficient method which houses a promising future in shallow water surveys. The advantages, promising future in shallow water surveys. The advantages, that is high data collection rate and high sensitivity, makes that is high data collection rate and high sensitivity, makes it an ideal choice for coastline surveys and it is obvious that it an ideal choice for coastline surveys and it is obvious that LiDAR will play a major role in geospatial community in the LiDAR will play a major role in geospatial community in the future.future.

Thank YouThank You