Roles of a hydrographic office and GIS/GPS – An outline survey

Roles of a hydrographic office and GIS/GPS – An outline survey


Commander Sudhir K. Mittal
Commander Sudhir K. Mittal
India Navy, National Hydrographic Office
[email protected]

This paper shall survey the current status of GIS usage for Hydrography with references to the National Hydrographic Office (NHO) Dehradun. GPS usage is also briefy touched upon. The major usages of GIS in Hydrography currently is in processing of digital field data, preparation of Electronic Navigational Charts (ENC) and paper navigational charts. This can be extended through a GIS based Hydrographic Information System (HIS), to cover the whole gamut of primary navigational products and services and supporting functions of a National Hydrographic Office including maritime boundaries, EEZ management and Coastal Zone Regulation. The Electronic Navigational Chart based on the international standard S57 has the potential to be used as the basemap for most GIS operations on data collected at sea and in the coastal zone. It can also be the common link for development of a nationwide GIS-enabled database for the oceanic and coastal domain. Certain National issues thrown up by the advent of GIS technologies have also been beifly touched upon. Aim of this paper is to prepare a sketch of what in the author’s opinion may be the areas of convergent interest between a Hydrographic Office like NHO Dehradun and the different interest groups represented in this conference.

Introduction to Hydrography, the National Hydrographic Office (NHO) and the Naval Hydrographic Department.

  • To set the scene a word on Hydrography and the National Hydrographic Office (NHO) Dehradun would be necessary. Hydrography is defined as the “That branch of applied science which deals with the measurement and description of the physical features of the navigable portion of the Earth’s surface and adjoining coastal areas, with special reference to their use for the purpose of Navigation. Its value was first recognised by the British during the American civil war when more ships floundered due to grounding than by the gunfire of American warships. Soon after, a specialised branch of Hydrography was established within the British Navy. What applied to warships applies even more critically to merchant shipping plying the oceans which shall remain the only truly viable and safe international thoroughfare for the foreseeable future. It is Hydrography which primarily enabled world wide trade and commerce by providing safety to marine transport through the navigational chart and supporting publications.
  • The Chief Hydrographer to the Govt of India discharges his functions through the National Hydrographic Office (NHO) at Dehradun and manages the Naval Hydrographic Department. Under the Allocation of Business Rules of the Govt of India, and the Navy Act the Chief Hydrographer to the Govt is assigned the responsibility for providing to the Indian Navy and Indian merchant mariner, navigational charts and related services for the Indian coast, ports, harbours and the adjoining high seas. Presently about 260 charts exist in the office portfolio covering the entire North Indian Ocean.
  • The Chief Hydrographer also supports EEZ management and delineation of maritime boundaries between adjacent coastal states under the UNCLOS III convention. Surveying and certifying the High Tide line and Low Tide Line for the purpose of CZM regulations is another of the national tasks of the Naval Hydrographic Department.
  • Several nautical publications are published by the NHO to provide to the mariner, detailed supplementary textual information on the coast, communications, ports and harbours. The National Hydrographic Office issues fortnightly bulletins called Notices to Mariners to update the Navigational charts and publications issued by the office. They are both posted to users of Indian charts and published on the web. ( For navigation hazards requiring immediate intimation to mariners, navigational hazards warnings called NAVAREA warnings are issued by the Chief Hydrographer to ships in the North Indian Ocean Region over INMARSAT and other radio networks.
  • With this background we shall now survey the three major application areas of Hydrography – Marine Navigation, EEZ Management and Coastal Zone Management, to outline the current usage of GIS/GPS, to introduce some issues involved with this usage, and to bring out the emerging potential applications. At the end of this certain national issues shall be touched upon briefly.

Marine Navigation
Electronic Navigational Chart (ENC) – Confluence of GIS, GPS and Object Oriented Databases

  • The initial objective of Hydrography was safe navigation of ships at sea and in connected waters. It is still its primary objective though its role has expanded considerably since the 1960s. The primary product under this application is a paper navigation chart depicting the coastline, ports and harbours, anchorages, depth contours, selected representative depths, navigational aids like lighthouses, buoys, wrecks and other underwater hazards, nature of sea bottom at intervals, tidal streams etc.
  • Two processes primarily determine safety of navigation with reference to the chart particularly in treacherous waters- one, speed of plotting successive ship’s positions on the chart by the mariner and two, speed of dissemination and incorporation of changes to the chart by the charting agency. Delay in either of the two has often resulted in disastrous consequences. It is difficult to think of many other uses of paper geographic data where these two processes are so critical. A novel application of GIS , GPS and satellite communications now allows both the processes to be executed digitally in real time. The product of this application is called an Electronic Navigational Chart (ENC). This is a GIS produced and GIS enabled version of the paper navigational chart. The Electronic Navigational Chart (ENC) and GPS position of ship, when input to a computer system called an Electronic Chart Display and Information System or ECDIS provides a real time graphic display of ship’s position on a video screen along and with respect to the geographical information contained in the ENC.
  • The geographic data is intelligent vector data and permits several other functions such as selective displays, querying of individual objects, navigational safety alarms, route planning. The ENC also carries and displays a digital copy of supplementary navigational publications like Sailing Directions or Pilots, the navigational equivalent of a thorough tourist guide for the coast, ports and harbours.
  • An outline of the ENC production process is given at Figure A. A paper navigational chart is scanned, geo-referenced, vectorised, and converted to an object oriented format called S57 to create the ENC. The S57 format has been standardised and promulgated by the International Hydrographic Organisation for exchange of hydrographic data. An ENC is one implementation of the S57 standard. This format can be a common link between all data producing and data using agencies on the seas and coastal areas. But more on that later.
  • Encryption1 : There is a major issue of data security facing ENC producing nations today. Need is two fold. One is against piracy and another against deliberate tampering with the data. While the commercial aspect is important enough the fact that HOs are liable for the authenticity of the data any unlawful update of the data will pose serious consequences for navigation. There are several impediments in achieving the goal of a security system. Some of these are :-
  • Lack of a standardisd encryption system.
  • Encryption is not included in the IMO approved standards for ECDIS, (the platform on which the ENC would be displayed.). This may pose a political problem if some nations so desire.
  • Potential weak points along the producer to user chain even with encryption, due to possibilities of human collusion.
  • Some of the options of implementing a security system without encryption are:-
  • Protect, not through encryption, but through signed licence agreements with the readiness to litigate against pirates.
  • Watermark the data to trace pirates.
  • Unique Result of International Co-operation: This product is a unique result of international co-operation between GIS specialists, cartographers, IHO, and IMO. Only an Electronic Navigational Chart produced under the authority of a Hydrographic office and in the S57 format can be termed as an ENC. Carriage of ENCs by ships in conjunction with ECDIS which conforms to IMO approved standards, has been declared by IMO to meet the statutory requirement under SOLAS convention, to carry updated paper charts.
  • Updates to ENCs: The update for electronic charts is envisaged to be carried out initially through CDROMS and later also through the web using INMARSAT maritime communication network. The latter has been successfully tested in North Europe. The current data encapsulation is currently designed as data descriptive interchange format i.e. it contains a description of the meaning of all data elements along with their content. more suited for land communications for efficient teecommunication interchnage the data could also be encoded using ISO 8824 encoding technique which describes data “in context” requiring additional processing based on previously known information on the data format.2

Paper Charts – GIS Improves Speed of Production
While ENC production is at various stages round the world, it has not yet come under extensive use as they have not yet been produced for all sea routes and ports and users want to wait before investing. Even when ENCs do come into primary use by marine shipping it is expected that demand for paper charts would remain. NHO has set up a digital workflow to publish paper charts using the common GIS enabled database created by vectorising the existing portfolio of paper charts for ENC production. The CARIS GIS in addition to producing the S57 dataset also outputs a design file. This is then taken into an Intergraph system to produce colour separates. These files are input to a Computer to Plate imagesetter system which yields the plate ready to print. This has enabled a dramatic reduction in the cycle time for producing a new edition of a chart and production of an entirely new chart.

Field Surveys and GIS /GPS

  • GIS and GPS technologies have been used in the field by the Naval Hydrographic Department (NHD) for more than 7 years. Data streams from several sensors onboard survey ships and boats are digitally logged on a common GPS position and time stamp. As the data is collected it can be compared to an underlay of historical data in real time. The raw field data is then fed to a field database for processing.
  • The data is normally collected on the WGS84 datum. This is essential as the ENC requires the use of this datum to enable worldwide navigation using GPS on one seamless charting scheme. This is especially important for digital display systems where switch from one chart to another is automatic.
  • A wide range of GPS methodologies are used for surveys. GPS, DGPS and RTK are used for afloat surveys. For geodetic control ashore, point positioning methods and baseline methods are used. For mapping the coastline, Kinematic and RTK is normally used. The latter is used onboard a helicopter increasingly. We today have system which pack sensors like echosounders, sonars and GPS in the same portable box. There is a possibility of using Pseudolites to cover areas of signal loss due to obstructions frequently encountered in ports and harbours.
  • The field data is received in the NHO on CDROMs. Here it is inspected, validated and approved for usage. Bathymetry is currently maintained as weeded fairsheets the way it is received from the field.

Emerging Utility – Hydrographic Information System
Contemporary technologies of data collection, GIS, RDBMS and data transmission have created a demand for a Hydrographic Information System, based on a central GIS which would be a single unified system capable of capturing and managing hydrographic data along with its core capabilities of information management, survey and chart planning support, data edit, quality control and production of digital charts and updates, paper charts and Notices to Mariners, Nautical publications and updates. It would need to perform most of the functions of a Hydrographic Office from data collection to data dissemination on a single integrated digital platform, integrated in terms of hardware, software, standards, data exchange, organization and policy. It would have to be linked to the internet and to other national databases to realise its full potential in the service of the nation. Many HO s round the world including ours are in various stages of defining such a system. A concept diagram of such a system is depicted at Figure B. The process of digitization of hardcopy data in NHO archives is underway. Definition of the Hydrographic Information System is also being undertaken. This would involve generation of several databases based on Oracle, like Hydrographic Source database, Hydrographic Production Source Database, Hydrographic Product Database, Field Database, Distribution database.

Safety of Life at Sea
Under the SOLAS (Safety of Life at Sea) convention the maritime safety Information is an internationally coordinated network of radio broadcasts containing information which is necessary for safe navigation, received on all ships by equipment which automatically monitors the appropriate frequencies and prints out in simple English only that information which is relevant to the ship. The three elements of maritime safety information is Navigational hazard warnings, met information and Search and Rescue coordination. Of these the Hydrographic Offices are often responsible for issuing Nav hazard warnings like in India. Currently the warnings are transmitted over INMARSAT network or coastal radio network as plain text. Due to the urgency involved it is accepted by the IMO that the warning may have to be transmitted even if the information is incomplete or unconfirmed. It may be apparent that a Hydrographic GIS suitably networked with coastal authorities such as port trusts , lighthouses etc could enable faster and more complete processing of any hazard report for preparation of a warning. To go a step further the warning could be issued with a picture or a video image of the affected object or area. INMARSAT 4 proposed to be introduced in 2004 to support Broadband- Global Area Network ( B- GAN) is expected to provide sufficient bandwidth to make this possible.3 This could make a significant enhancement to safety of life at sea.

EEZ Management

  • Management of EEZ involves several government and private agencies collecting data and processing it for various purposes. Very often the same data is collected by several agencies in the same area to develop the same products but for different purposes. While the concept of reducing redundancies and developing synergies is a laudable one, it will always have its limitations in a huge and young nation like ours, unless an internal momentum develops to overcome certain human obstacles. It will need tough decisions may be even a legislation. Something like the Japanese legislation on geodetic datum.
  • There is though a positive aspect to these redundancies. The duplication of data provides an excellent opportunity for validation and quality assurance of the data. One of the ways to make it practicable is to feed all this data to a GIS enabled central database for comparison of layered data against a common base map depicting the bathymetry of the sea floor, the coastline and other natural features.
  • This process would also enable preparing products depicting interactions of different data layers for analytical and management purposes. This could be done by adding additional objects to the ENC using the facility of extensions to the S57 standard. An example is a map depicting fish catch data against SST to validate primary productivity charts prepared by department of space. Or a chart with sonar and magnetic data draping the bathymetry. EEZ management involves or would involve mapping of the following major elements :-
  • Living resources in the water column and on the sea floor.
  • Special ocean features and ecosystems like mid ocean atolls, banks, mid oceanic ridges, flats
  • Submarine pipelines and cables.
  • Gravity and magnetic mapping of the ocean floor.
  • Nature of seabottom
  • Ocean currents and tidal streams.
  • Mineral nodules on the deep ocean floor.
  • Average wave and wind patterns
  • Average cloud cover
  • Frequency and paths of tropical storms
  • It must be apparent what dividends a fusion of these data elements would yield. There are a few minimum requirements to enable the fusion of all this data collected and processed by different agencies like NIO, GSI, ONGC, oil prospectors and producers in the private sector, CESS, NIOT, FSI, CMFRI, CWPRS, port trusts, state maritime boards, minor ports survey organisation etc, Telecom industry, state urban development authorities etc. What these are and how they may be met ? The requirements are :-
  • A standard base map of the entire Indian EEZ including the coastline: This is provided by the Electronic Navigational Charts produced by the Naval Hydrographic Department as mentioned above. This is the chart produced based on paper charts issued under the authority of the Chief Hydrographer to the Govt of India. The ENC portfolio is under completion and would be commercially available when ready.
  • A standard data exchange format between the data producers and the central GIS. This could be the International standard S57 which is also the format in which ENC data is encoded and encapsulated. Apart from obviating the need at the central GIS for a host of data conversions, this would also enable compatibility with the ENC for the purposes of GIS operations. The standard is based on object coded data and recognises full topology.
  • Conversion software from commonly used formats for spatial data to S57. As several IHO member countries today are producing ENCs which need to be in S57 format as per IMO resolutions, conversion software is readily available off the shelf.
  • A nodal agency to establish and maintain the central GIS . This could be INCOIS.

Fishery Charts
We often ask a question how capital investment in technology will make the life of the common man easier as well benefit him economically even as it benefits the nation. The ENC technology with low cost PCs can readily be harnessed to do just that in a manner more direct than the so called trickle down effect. The basic ENC already has some data relevant to fisherman such as wrecks, obstructions and maritime boundaries. This could be enhanced by additional data like FSI data regarding seasonal catch, assessment on resource distribution, sensitive and forbidden areas, primary productivity distribution, ocean currents etc. To enable non English speaking fisherman to utilise these charts it is possible to provide the text in any scripts of the different coastal languages of India as the S57 format supports these scripts. A pilot project could perhaps be taken up by one of the ICAR institutes engaged in fisheries research. State governments could follow-up the production. If nothing is done except the provision of regional script it would a great dual use of the ENC.

Coastal Zone Management

  • Land and Sea Data: There is a need to establish linkages between Electronic Land maps and Electronic Navigational charts to exploit the full potential of both towards Coastal Zone management. A lead can be taken from the efforts under the aegis of the IHO, to harmonise the ENC with the Digital Navigation Chart (DNC) produced by the US. The latter used by the US Navy also incorporates land data essential for amphibious operations which is not necessary for navigation.
  • Coastal Zone Regulations: A Hydrographic GIS would contribute to the HTL and LTL requirements for establishing zones for coastal regulation. It shall also contain the shoreline with mangroves and such sensitive ecosystems.
  • Tourism: Tourism industry could benefit from the nature of coast that would figure in the Hydrographic Database. Details on small harbours, boat landing sites There is a possibility being looked at by HOs to produce coastal and sea tourism maps from their Hydrograhic GIS.
  • Marine Boundaries and Outer Edge of the Continental Shelf: This is yet another important area of GIS application for Hydrographers. GIS has been found as the most appropriate tool to determine EEZ boundaries between opposite or adjacent coasts, according to the guidelines of the UNCLOS IV convention. The convention provides for extension of EEZ based on multiple geological and bathymetric criteria of the ocean floor. How best to exploit these criteria to maximize the EEZ for a coastal state is a geospatial problem for which a GIS solutions are being applied by the HO s round the world. We have been using the product called CARIS LOTS of a Canadian firm called CARIS.

General Implications of GIS Technology for Mapping/Charting Agencies

GIS is not inexpensive. If expenditure incurred in GIS technologies in the country has to reap the desired harvest for the nation all mapping agencies may need to consider the following issues :-

  • Closer and long term Govt / Industry partnership.
  • Careful attention to management of change
  • Intra-agency reorganisation
  • Inter-agency reorganisation
  • Recognition of the need to initiate a process which successively integrates geospatial mapping functions.
  • Framing of a Govt of India policy on exploitation of the potential of GIS technology for development.

Conclusion – Three Messages

  • The convergence of the technologies of digital data collection at sea with computers, GPS and GIS is not only enabling Hydrographic Offices to enhance safety of marine transport by more effective and versatile products and services. It is also shifting the focus of hydrography to data processing ashore from data collection afloat. In addition to navigational safety , GIS has also enabled Hydrographic Offices to discharge their roles effectively in the fields of delineation of maritime boundaries, EEZ management, Coastal Zone Management. The concept of a Hydrographic Information System would enable integration of all activites of a Hydrographic Office on a single integrated digital platform. This could be further integrated to oceonographic and topographical databases. Before concluding the author wishes to underline three messages of this paper :-
  • The ENC as Basemap for Oceanic/Coastal GIS Domain: The ENC provides an enabling tool for building a comprehensive GIS enabled database for the oceanic and coastal domain. It provides a base-map for the sea. Its data is in an international standard format for hydrographic data exchange called S57. Many COTS conversion software are available for this format.
  • Hydrographic GIS: is an emerging utility which not only promises effectiveness and speed in providing hydrographic products and services but can provide much needed services to other emerging users of hydrographic and oceanographic data like administrators, scientists, engineers. This GIS could be a backbone for ocean related data in the larger National Geospatial Data Infrastructure.
  • Hydrographic and Topographical Mapping in Coastal Zone- Linkages: This one area where of necessity several agencies are involved in mapping. Integration of electronic mapping by land mapping and hydrographic agencies will enable full potential of GIS for coastal Zone Managment. There is IHO/NATO initiative in harmonising the S57 format of ENC and DIGEST format of Digital Nautical Charts produced by the US Navy. The DNCs are meant for the military and contains additional data on land required for military operations. This could be the basis of a simir initiaitive in harmonising our ENCs and land electronic mapping efforts.
  • Advent of GIS cries out for a review of the national organisation in which we collect process and map data on land sea and the atmosphere. Several countries in the West have responded to this voice. We have also to involve our home grown GIS industry in this review and develop a closer strategic and operational relationship with them. Quick fix short term solutions off the shelf solutions may not justify the huge cost involved. Off the shelf kernels may however be used for long term maintenance and development.
  • The association of GIS with spatio-temporal information has even a philosophical implication. What is the human body but the result of spatial information with a time element. The children of Maya, the Indian seers, said Map is not the territory. Never made maps never held territory. Along came the colonists who said if you have the map you have the territory. And took all the territory. All the technology and knowledge systems of today in an ironic way leads us to the original conclusion though stated differently – Map is the only territory. We missed the Industrial revolution, perhaps also the Revolution in Military Affairs, but let us not miss the Information revolution. The world made of Nam and Rup ie Name and shape. Shape implies position and space , name implies a category. And both imply a GIS. The whole Universe is but Nam and Rup as the sages said waiting to be unfolded by the paradigm of GIS. Let us therefore convert our nodes into arcs and arcs into areas and areas into faces and build an integrated national GIS with full topology.

About the Author
Cdr Sudhir K Mittal graduated from Jawaharlal Nehru University New Delhi/National Defence Academy Khadakwasla, and post graduated from Madras University / Defence Services Staff College Wellington, Nilgiris India. He has undergone the IHO Cat A Long Hydrographic Course from the Naval Hydrographic School Goa. He is currently posted as a Deputy Director at the National Hydrographic Office after years of experience in field surveying onboard survey ships in different positions, and an earlier tenure at the National Hydrograpahic Office Dehradun.

Views expressed in this paper are entirely those of the author and do not in any way reflect the official policy of the National Hydrographic Office.