World Hydrography Day was celebrated on 21st June with the 2016 theme “Hydrography – the key to well-managed seas and waterways”. What is little known is that GIS and geospatial technologies lie at the core of Hydrography surveys. Any hydrography data would be incomplete without georeferencing or positioning. Similarly, oceans and remote expanses of water could not be mapped or documented without satellite and aerial imagery.
Most countries have successfully surveyed and documented their inland water bodies. However, the oceans have received less attention with only 12% mapped so far. Considering that the oceans form the resource base of food, medicines, transport and infrastructure, mapping of oceans is extremely critical. A worldwide movement to spread awareness and sharing of Hydrography data has begun with Hydrography events and offerings like the Ocean Basemap from Esri. While competitions and research grants (see below) aim to have more professionals on board, to research and map the oceans.
Hydrography is best defined as the science of measuring and attributing water bodies and adjoining land areas. This includes riverine systems, coastlines, harbours and the seas. Hydrography further explores the impact of ocean developments and climate change on the coast, estuaries, piers, seawalls and offshore structures.
Hydrographic surveys collect four types of data:
- water depth / height of water body or sea;
- heights of bordering and underwater land formations;
- tide levels / tidal datums;
- positioning and orientation.
Hydrography and GIS
Hydrography data is represented as digital vector geospatial dataset of surface water features (point, line, polygon) with Hydrography attributes. As in many other fields, GIS and geospatial technologies form the mainstay of Hydrography – surveys, validation, processing, analysis and distribution. As GIS extends an object-relational database, it can store geographic data, perform data extraction, validation and analysis, produce digitized charts, maps and authoritative datasets Thus helping reduce operating costs and time.
In recent years, a data-centric approach has been adopted towards collection and assimilation of Hydrography data. Digital charts for navigation are thus fast replacing traditional nautical charts. Hydrography datasets, in particular marine datasets, are huge. Data collection methods and sources are also varied. This is where GIS steps in with its ability to combine/overlay, store, analyze, visualize and distribute large datasets. It also helps to create thematic layers/maps and generate specific models. With a wide stakeholder base that spans geographies across the world, the only accepted spatial data storage format becomes the geodatabase. GIS supports creation of extensive Hydrography geodatabases. Like the National Hydrography Dataset (NHD) and the marine SDI. GIS uses the attributes imbedded in such datasets to generate specialized information that is applied in various scenarios. Customized nautical charts, tide and current tables, thematic maps like the Tsunami inundation maps are some popular outcomes.
How Geospatial is used in every stage of the Hydrography life-cycle:
Geospatial technologies are crucial for data gathering and validation. While GIS forms the all-pervasive platform for data storage and visualization. In recent years, extensive application of Cloud GIS and Big Data GIS are also helping to maximize spatial analysis for predictive modeling.
GIS as a tool in Hydrography – Cartography, Digital cartography, desktop mapping, crowdsourced Hydrographic data /VGI (Volunteered Geographic Information); data validation, creation of Hydrographic geodatabase, nautical charts, geodetic and tidal information, tidal zone modeling, TIM (Tsunami inundation maps), Hydrographic modeling and analysis.
Geospatial Technologies in Hydrography – remote sensing /satellite imagery, aerial imagery, LiDAR, satellite positioning / GNSS technologies, GPS, UAVs / drones, AUVs (Autonomous Underwater Vehicles)with integrated GPS and INS (inertial navigation system), motion sensors, sonars, ground based radar (HF radar / Microwave radar), bathymetry (satellite, LiDAR, crowdsourced) and several other platforms that integrate the geospatial.
Maritime / Naval Agencies (Geointelligence), Coastal Monitoring Agencies, Hydrography Data Stewards & Maritime SDI groups, Engineering firms and consultants (off-shore tunnels, bridges, ports, telecommunications networks), Oil and Gas Companies, Offshore Energy firms (wind, geothermal, tidal), Deep-sea mining companies, Commercial shipping / Nautical Charting agencies, First responders (maritime accident investigation, oil /toxic spills, aircraft wreck discovery), Flood/ Tidal Surge/ Tsunami monitoring agencies, Natural Resource Management participants, waterway transport agencies, deep-sea forensic researchers and explorers, land use planners, navigators
The Future of GIS in Hydrography
GIS technologies have enormous scope in the following:
- wider swath bathymetry coverage
- aerial imagery fused with LiDAR survey and 5-band satellite imagery for in situ clarity in turbid waters
- mapping in Arctic regions where ice-free lakes occur for very short periods – with GNSS receivers set up to maximize geometric data quality of LiDAR data.
- Hydrographic data crowdsourcing for creation of wider and detailed geodatabases
- software development using GIS as an enabler, in an open source ecosystem
- off-the-shelf responsive mapping applications for wider use
- enhanced GIS software to accommodate large datasets generated by maritime surveys and models
- more productive use of AUVs equipped with sensors and LiDAR
- production of thematic maps that can be applied in various scenarios
- development of advanced technologies with integrated INS
Hydrography – A Geo-Convergence of Disciplines: surveying, cartography, geodesy, geoscience, geomatics, software development, data management, map creation and analysis, Remote Sensing, Bathymetry, UAV and more.
Collaborative Projects / Research Opportunities
Esri’s Ocean Basemap
Shell Ocean Discovery $7 million XPRIZE global competition challenges teams to advance deep-sea technologies for autonomous, fast and high-resolution ocean exploration. This intends to further the cause of exploration and mapping of the ocean floor, with entries already pouring in.
The Integrated Ocean Observing System (IOOS) offers $31 million in grants to support observation of the ocean, coasts and the Great Lakes (U.S.).
Agencies leveraging GIS in Hydrography – National Geospatial Agency – Maritime Safety Information; NHD; GSDI – Marine SDI; Open Water Data initiative; National Oceanic and Atmospheric Administration (NOAA), State / Government administered Hydrographic databases
- Maritime Safety Information, NGA – Resource on Hydrography
- New Global Hydrography Derived From Spaceborne Elevation Data
- NHD Training
- Water Resources of the United States
- USGS – National Hydrography Data