Introduction to Hydrographic Surveying

Topic : Definition of Hydrography

The Science of measuring, describing and
depicting :
Nature and Configuration of the Seabed
Bathymetry, geology, geophysics
Geographical relationship to Land Mass
Positioning
Physical properties of the atmosphere (reflection)
What is Hydrography?
Introduction to Hydrography
The Science of measuring, describing and
depicting :
Characteristics and Dynamics of the Sea
Tidal and non-tidal sea level variations
Currents and waves
Seawater acoustic propagation properties
Seawater thermohaline properties
What is Hydrography?
Introduction to Hydrography
3 Main Aspects of Hydrography
Main Aspects of Hydrography
Coastal Offshore
Oceanic
1) Coastal
development of ports & harbours;
coastal erosion problems;
utilization of harbour and coastal conservation
services;
safety of navigation in coastal waters.
Main Aspects of Hydrography (Coastal)
Main Aspects of Hydrography
2) Offshore
provision of hydrographic data as an extension
of the coastal zone normally encompassing the
continental shelf;
The development of mineral deposits, including
hydrocarbons;
Provisions of data for fisheries management.
Main Aspects of Hydrography (Offshore)
Main Aspects of Hydrography
3) Oceanic
Acquisition of hydrographic data in the deep
ocean areas for the depiction of sea floor
geomorphology.
Main Aspects of Hydrography (Oceanic)
Main Aspects of Hydrography
To answer this question, we must look at what the
sea mean to society.
What is The Role of
Hydrography in Society?
Ocean Resources
Ocean Resources
Uses of Ocean Mapping
Uses of Ocean Mapping
Need for Ocean Information
Need for Ocean Information
Hydrography in Society
Ocean Resources
3 Major Sectors
Resource Management Objectives
Information Infrastructure
Ocean Resources
Minerals
Fisheries
Shipping
Ocean Resources (3 Major Sectors)
Ocean Resources
Ocean Resources
(Resource Management Objectives)
Ocean Resources
To
Improve
Safety Productivity
Environment Monitoring
Sovereignty Protection
Ocean Resources
(Information Infrastructure)
Information Infrastructure:
Application of hydrographic science and
technology to the productive, quantitative,
commercial management of these ocean
resources.
Ocean Resources
Need for Ocean Information
Ocean Resource Management
Ocean Service Industry Development
Need for Ocean Information
Need for Ocean Information
(Ocean Resource Management)
Ocean Resource Management:
Size of coastal states Exclusive Economic Zone
(EEZ) entails major management responsibilities.
Keys to success are knowledge, understanding
and technology.
Competitive ocean industries need leading-edge
technologies.
Need for Ocean Information
Need for Ocean Information
(Ocean Service Industry Development)
Ocean Service Industry Development:
Potential: there is a need for world-class ocean
technology.
Advantages: to the first to develop and use new
technology.
Growth: supply technology for global ocean
development.
Third world starting to manage and develop
ocean resources.
Need for Ocean Information
Use of Ocean Mapping
Productivity Improvement
Marine Safety Improvement
Improved Environment Quality
Improved Sovereignty Protection
Use of Ocean Mapping
Use of Ocean Mapping
(Productivity Improvement)
Productivity Improvement :
Requires improved knowledge of nature and
shape of seabed.
Part of this knowledge = bathymetry, geology &
geophysics maps.
Other knowledge needed (e.g. species
population and dynamics).
Use of Ocean Mapping
Use of Ocean Mapping
(Marine Safety Improvement)
Marine Safety Improvement :
Requires improved mapping of hazardous depth
anomalies.
Other knowledge needed (e.g. currents, tides,
weather).
Use of Ocean Mapping
Use of Ocean Mapping
(Improved Environment Quality)
Improved Environment Quality :
Requires improved knowledge of tides, currents,
weather and bathymetry to predict nutrient and
pollutant movements.
Use of Ocean Mapping
Use of Ocean Mapping
(Improved Sovereignty Protection)
Productivity Improvement :
J urisdiction boundary definitions are based on
bathymetry and continental slope geology and
geophysics.
Use of Ocean Mapping
Survey Responsibilities
Ships Master Responsibility
Officer on Watchs Responsibility
Hydrographers Responsibility
Other with Specific Responsibility
What Legal Responsibilities
does Hydrography Involved?
Legal Responsibilities
Survey Responsibilities
Ships Masters Responsibility :
Overall ships operations and safety
Officer on Watchs Responsibility :
Ships navigation and safety
Hydrographers Responsibility :
Accurate and efficient survey execution
Others with Specific Responsibility :
Harbourmaster, port engineer, survey contractors
Legal Responsibilities
Product Responsibilities
User Responsibilities
Hydrographer Responsibilities
Negligence
What Legal Responsibilities
does Hydrography Involved?
Legal Responsibilities
User Responsibility :
Ships must carry official up-to-date charts and
publications.
Mariners should not rely on any single source of
navigation info.
Product Responsibilities
(User Responsibilities)
Legal Responsibilities
Hydrographer Responsibility :
Hydrographer must assure accurate up-to-date
charts are available.
Chart production is partly an art discretion
about quantity and nature of information shown
(neither too little nor too much).
Product Responsibilities
(Hydrographer Responsibilities)
Legal Responsibilities
Negligence :
For successful legal action against hydrographers,
must show
chart was relied on for navigation
chart contained errors
errors were due to hydrographers negligence
claimed damages were caused by these errors.
Negligence = usual expertise and competence not
exercised.
Product Responsibilities (Negligence)
Legal Responsibilities
Data Acquisition
Data Acquisition
Sampling
Current
Measurement
Positioning
Geophysical
Measurement
Echo
Sounding
Coast lining
Shore
Control
Water level
measurements
Sweep
Coverage
Data Acquisition
Each country will have their own procedures for
scheduling surveys, but the process usually starts
with a request.
These requests come from many sources and
indicates that there are likely to be many more
requests than can be serviced.
Hydrographers are involved in acquiring many kinds
of data. A typical nautical charting survey will involve
almost all of these activities.
Data Acquisition
Who decides a Hydrographic Survey is needed, WHY?
Data
Processing
Data Processing
Position
Time
Depth
Field
Record
Tide
Record
Time
Water level
Reduced Records
Boat Board
(Position vs Time)
Interactive Editing Manual Inspection
Field Sheet
(Depth vs Position)
Data Processing
In processing data from a hydrographic survey, time
tags are used to correlate different kinds of data.
In the case of a conventional hydrographic survey:
on board the survey vessel, separate
measurements of position, depth and time
must be correlated;
while at a wharf or other site, record of water
level variations due to tides, together with time,
must be recorded.
Data Processing
Data Processing
These records are combined to give 2 working
documents:
i. the boat board, which shows what area has
been surveyed, and when;
ii. and the field sheet, which maps the tide-
reduced depths.
Data Processing (Cont..)
Data Processing
Data
Presentation
Data Presentation
Photo
Reduce
Data
Auto-
mated
Base-Plot
1
Inspect
Mosaic
Compile
Mosaic
Com-
pilation:
Select
Data
Amend
Mosaic
Amend
Compi-
lation
2
Inspect
Compila-
tion
Nomen-
clature
Aids to
Navigation
Colour
Separation
Drafting
high and low water,
soundings, bathymetry
topography, roads
3
Inspect drafting
Content, quality
Final
Negative
Prep
Amend
Drafting
Colour
Proof
4
Inspect registration,
Content, quality,
colour
Amend
Colour
Proofs
5
Inspect colour
registration
HQ
review
Final
Amend,
Add date
6
Final
Inspection
7
Inspect
Print
Quality
Release
Approved
Print
Chart
Add
Notice to
Mariners
Distribute
Chart
Data Presentation
The data from a nautical charting hydrographic
survey (the field sheet and boat board) typically go
through many processing steps before they ended as
a distributed hydrographic chart.
Existing historical data, data from other sources and
complementary data (such as topography, cultural
features, aids to navigation) are all carefully
consulted and reconciled with the new survey data, a
process called compilation.
Data Presentation
Data Presentation
There are several careful inspections along the way.
Unlike land maps, hydrographic charts are legal
documents, used as navigational instrument.
A charting error could well cause a disaster, hence
hydrographers and marine cartographers are
extremely conservative about the information placed
on a hydrographic chart.
No matter how spurious the report of a possible
navigation hazard might be, it would be deleted from
a chart only after the most rigorous checking and re-
checking indicates it does not exist.
Data Presentation (Cont..)
Data Presentation
There are several recent challenges to the
hydrographic tradition of careful methodical chart
compilation:
The impact of true 100% coverage on one
hand and the enormous quantities of data on
the other hand, which result from new high
density depth data acquisition system.
Data Presentation (Cont..)
Data Presentation
The impact of chart user having better
positioning technology available (DGPS) than
was used for the surveys upon which the chart
is based there is a greater need to show the
user what kind of accuracy level and reliability
can be placed on charted features.
Data Presentation (Cont..)
Data Presentation
The growing demand for fast chart production
turnaround, so that shipping has access to the
latest information.
Perhaps most of all, the move towards digital chart
production and data distribution, which requires a
complete re-thinking of the chart production process.
Data Presentation (Cont..)
Data Presentation
Data
Maintenance
Data Maintenance
Coast Guard:
Correction to
-nav aids
-list of lights
Coast Guard
National
Hydrographer:
Correction to
-charts
-Sailing direction
-Small Craft guides
Nav danger or
nav aid change
discovered
Notices to
Mariners
Marine
Information
Report
Notices to
Shipping
Coast
Guard
Radio
Data Maintenance
Also unlike land maps, it is extremely important to
keep navigational charts up to date. Changes to the
area cheated which have occurred since the chart
was finalized are added, often by hand.
Notices to Mariners is a weekly list of chart
corrections issued by each maritime nation, due to
new construction, changes in buoys and other
navigational aids, etc.
Each chart sold is stamped with the date of the last
Notice entered on the chart.
Data Maintenance
Data Maintenance
It is then the responsibility of the mariner to keep his
own charts up to date.
The costs to a hydrographic service of manually
updating charts can be considerable.
In September 1989, the Danish Hydrographic Service
stopped hand correcting their 170 charts. Instead
they are reprinting with corrections more often than
before and distributing a monthly correction list which
describes the necessary corrections for each chart
(International Hydrographic Bulletin, August 1990).
Data Maintenance (Cont..)
Data Maintenance
In Canada, well over 1000 Notices to Mariner are
issued annually. Such corrections, for ships carrying
the complete set of over 1000 Canadian charts, have
been estimated to take a least 500 person-hours per
year.
Many ships on international routes carry charts from
several nations, all of which must be updated
regularly as well.
Data Maintenance (Cont..)
Data Maintenance
Data
Application
Data Application
Hydrographic Data Application
User Group
Marine Transportation
Coastal Zone Management
Mineral Resources
Environmental Concerns
Data Application
User Groups
Mariners
Marine Biologists
Oceanographers
Ocean Engineers
Geologists & Geophysicists
Environmentalists
Hydrographic Data Application
(User Groups)
Data Application
Marine Transportation
Safety of Navigation
Channel Dredging
Inland Waterways (rivers, lakes, reservoirs, etc.)
Hydrographic Data Application
(Marine Transportation)
Data Application
Coastal Zone Management
Port Construction
Waste Dumping Grounds
Aquaculture
Tidal Power
Sand and Gravel Resources
Erosion Control
National Boundaries
Land Reclamation
Hydrographic Data Application
(Coastal Zone Management)
Data Application
Mineral Resources
Exploration and exploitation of undersea
resources
Need bathymetry, geomagnetic, gravimetric,
seismics profiling information in EEZ
Hydrographic Data Application
(Mineral Resources)
Data Application
Environmental Concerns
Marine Transportation and the extraction of
undersea petroleum resource caused pollutions
Prediction, combined with appropriate
meteorological observations to predict movement
of oil spills
Hydrographic Data Application
(Environmental Concerns)
Data Application