AD-SDI DATA CONTENT STANDARD

Transcription

1 AD-SDI DATA CONTENT STANDARD COASTLINE DATA Version 1.0 August 2010 Prepared by Abu Dhabi Systems and Information Centre (ADSIC) Abu Dhabi, UAE

2 REVISION HISTORY Revision # Reason Effective Date 1 Original Draft July Incorporate ADM comments and enhanced Content and Data Dictionary August 2010 DISCUSSION HISTORY Discussion # With Date Summary 1 ADM Aug 2, 2010 Added Fig. 3 and section Page 2 of 23

3 Table of Contents 1 Introduction Scope, purpose, and application Scope Purpose Application Terms and definitions Symbols, abbreviated terms, and notations Methodology Tidal Datum Tidal Measurements Tidal and Geodetic Datum Relationships Other Applications of Tidal Data Content Model Coastline Definition Coastline Classification Coastline Boundary Data Dictionary Appendix A: Information on Maritime Zones Appendix B: Opportunity to Create Coastline Data References Page 3 of 23

4 1 Introduction The Emirate of Abu Dhabi has a rather lengthy coastline extending to several hundreds of kilometers (the coastline distances can differ significantly based on the scale of the maps). Commonly, coastline is the line that forms the boundary between the land and the sea. However, a precise line that can be called a coastline cannot be determined due to the dynamic nature of tides. The term coastal area is used instead, which is a spatial zone where interaction of the sea and land processes occurs. Figure 1: Coastline of the Emirate of Abu Dhabi Figure 2: Complex Coastline around Abu Dhabi Mainland Page 4 of 23

5 Coastal areas have economic, cultural, and aesthetic values. They provide critical habitat, store nutrients, and provide buffers to coastal communities from flooding, waves, and longterm changes in sea level. Coastal ecosystems are being lost at alarming rates due to natural and manmade causes, raising restoration as a priority activity. Sound coastal ecosystem management practices, including planning and monitoring restoration projects, coastal engineering and development, and land-use planning, must be framed by a thorough understanding of the relationship between water levels, tidal datums, and geodetic, or landbased, elevations. 2 Scope, purpose, and application 2.1 Scope The Abu Dhabi Emirate coastline is a baseline for administrative boundaries, nautical charts, and commercial and natural resource utilization and management. A proper definition of coastline involves a thorough understanding of the relationship between water levels, tidal datums, and geodetic, or land-based, elevations. Effective use of coastline data requires a highly defined logical data structure that is interoperable, efficient and applicable to a broad base of government and private sector demands. Current practices have led to a highly variable coastline data infrastructure. 2.2 Purpose This FGDS Data Content Standard is intended to present a framework and a methodology to organize the coastline data sets maintained by different entities. It is designed to enhance the coastline framework by providing technical guidance on coastline semantics, data structures and their relationships to the developers and users of coastline data. The coastline data is essential in the determination of the baseline and measurement of maritime zones. United Nations Convention on the Law of the Sea (UNCLOS) set the limit of various maritime areas (See Appendix: Information on Maritime Zones), measured from a carefully defined baseline. In order to make decisions that will remain relevant into the future, an accurate picture of the present scenario of the coast as well as informed projections of future trends are necessary. 2.3 Application Harmonizing the coastline data content will assists in several areas such as: Preparation of nautical charts, coastline maps, and other map publications by stakeholders that show the Emirate coastal boundary. Determination of the baseline, a line that is used as a base for delimiting a coastal state's maritime zones. Providing real-time oceanographic and meteorological information for navigation, emergency management, and hazard mitigation. Monitoring of sea level rise through measurements of local Mean Sea Level. Page 5 of 23

6 Inundation analyses and study of seasonal variations in support of wetland restoration and ecosystem management. Oceanographic assessments and other analyses for a comprehensive understanding of the ocean and coast. Providing geospatial foundation for Marine Spatial Planning Protecting the coastline through appropriate zoning and development guidelines. Legal studies on national, Emirate, and private boundaries along the coast. Accurate determination of sea level that is crucial for the establishment of Nautical Chart Datum and Tide Tables. Ensuring accuracy, relevancy, and currency of nautical charts and tide tables Developing tidal observations and sea level information in support of understanding climate change. Planning and regulatory processes required for utilization of tides, currents and other oceanographic means being harnessed for energy generation. These application areas are highly relevant to coastal surveyors, coastal managers, and everyone working and living along the coasts. Page 6 of 23

7 3 Terms and definitions The following definitions and explanations of terms clarify the subject of the Standard: Baseline Bay Coastline Coastal Boundary Coastal Zone (legal definition for coastal zone management) Cove Exclusive Economic Zone (EEZ) Inlet A baseline is the line from which the seaward limits of a State's territorial sea and certain other maritime zones of jurisdiction are measured. Normally, this is the same as coastline. When the coastline is deeply indented, has fringing islands or is highly unstable, straight baselines may be used. A bay is an area of water mostly surrounded or otherwise demarcated by land. Bays generally have calmer waters than the surrounding sea, due to the surrounding land blocking some waves and often reducing wind. Coastline is the line of mean low water along that portion of the coast that is in direct contact with the open sea. It is the fringe of land at the edge of the sea. See shoreline. The mean high water line (MHWL) or mean higher high water line (MHHWL) when tidal lines are used as the coastal boundary. Also, lines used as boundaries inland of and measured from (or points thereon) the MHWL or MHHWL. See marine boundary. The term coastal zone means the coastal waters (including the lands therein and there under) and the adjacent shore-lands (including the waters therein and there under), strongly influenced by each and in proximity to the shorelines of the several coastal states, and includes islands, transitional and intertidal areas, salt marshes, wetlands, and beaches. The zone extends to the international boundary in areas seaward to the outer limit of the territorial sea. The zone extends inland from the shorelines only to the extent necessary to control shore-lands, the uses of which have a direct and significant impact on the coastal waters. Excluded from the coastal zone are lands the use of which is by law subject solely to the discretion of the Government. A cove is a small type of bay or coastal inlet. They usually have narrow, restricted entrances, are often circular or oval, and are often inside a larger bay. Small, narrow, sheltered bays, inlets, creeks, or recesses in a coast are often considered coves. Colloquially, the term is used to describe a sheltered bay. An EEZ is a sea zone over which a state has special rights over the exploration and use of marine resources, under the law of the sea. It stretches from the edge of the state's territorial sea out to 200 nautical miles (370 km) from its coast. In casual use, the term may include the territorial sea and even the continental shelf beyond the 200 mile limit. See Appendix: Information on Maritime Zones for more details. An inlet is a narrow body of water between islands or leading inland from a larger body of water, often leading to an enclosed body of water, such as a sound, bay, lagoon or marsh. In sea coasts an inlet usually refers to the actual connection between a bay and the ocean and is often called an "entrance" or a recession in the shore of a sea, lake or river. Page 7 of 23

8 Isthmus Marine Boundary mean low water line (MLWL) mean water level (MWL) mean diurnal tide level (MDTL) mean high water line (MHWL) mean higher high water line (MHHWL) mean lower low water line (MLLWL) mean water level line (MWLL) Peninsula Shore Shoreline (Coastline) Tide Gauge Tide Station An isthmus is a narrow strip of land connecting two larger land areas usually with water-forms on either side. For example, the Isthmus of Suez in Egypt connects Africa and Asia. Canals are often built on isthmuses to create a shortcut for marine transportation. The Suez Canal, connecting the Mediterranean Sea and the Red Sea allows water transportation between Europe and Asia without navigating around Africa. The mean lower low water line (MLLWL) when used as a boundary. Also, lines used as boundaries seaward of and measured from (or points thereon) the MLLWL. See coastal boundary. The line on a chart or map which represents the intersection of the land with the water surface at the elevation of mean low water. A datum. The mean surface elevation as determined by averaging the heights of the water at equal intervals of time, usually hourly. Mean water level is used in areas of little or no range in tide. A tidal datum. The arithmetic mean of mean higher high water and mean lower low water. The line on a chart or map which represents the intersection of the land with the water surface at the elevation of mean high water. See shoreline. The line on a chart or map which represents the intersection of the land with the water surface at the elevation of mean higher high water. The line on a chart or map which represents the intersection of the land with the water surface at the elevation of mean lower low water. The line on a chart or map which represents the intersection of the land with the water surface at the elevation of mean water level. A peninsula is a piece of land that is surrounded by water but connected to mainland via an isthmus. It is a piece of land projecting into water from a larger land mass. The term shore refers to parts of the land which adjoin any large body of water, including sea and lakes. Therefore a shoreline may include the line along the lakes also. The intersection of the land with the water surface. The shoreline shown on charts represents the line of contact between the land and a selected water elevation. In areas affected by tidal fluctuations, this line of contact is the mean high water line. In confined coastal waters of diminished tidal influence, the mean water level line may be used. See coastline. An instrument for measuring the rise and fall of the tide (water level). The geographic location at which tidal observations are conducted. Also, the facilities used to make tidal observations. These may include a tide house, tide (water level) gauge, tide staff, and tidal bench marks. See primary control tide station, secondary control tide station, tertiary tide station, and subordinate tide Page 8 of 23

9 station. Tide Tables Vertical Datum using Tidal Data Tables which give daily predictions of the times and heights of high and low waters. These predictions are usually supplemented by tidal differences and constants through which predictions can be obtained for numerous other locations. This is vertical datum or water level from which all heights and depths are measured and used to produce a seamless surface by linking depths and elevations data in a common datum. This enables a user to integrate bathymetric and topographic coastal data from different sources having different reference datum. Page 9 of 23

10 4 Symbols, abbreviated terms, and notations The following symbols, abbreviations, and notations are applicable to this document. Symbols, abbreviations, and notations applicable to multiple parts are listed in the Base Document. ADM Abu Dhabi Municipality AD-SDI Abu Dhabi Spatial Data Infrastructure DEM Digital Elevation Model DOT Department of Transport, Abu Dhabi EAD Environment Agency Abu Dhabi FGDS Fundamental Geographic Data Set GRS Network GPS Reference Station Network of the Emirate of Abu Dhabi LIDAR MSD SRS UPC LIght Detection And Ranging Military Survey Department, Abu Dhbai AD-SDI Spatial Reference System Standard Urban Planning Council Page 10 of 23

11 5 Methodology The delineation of land and sea interface is carried out using tidal datum. The intersection of the elevation of a tidal datum with the sloping seashore forms a line used as a horizontal boundary. In turn, this line is also a reference from which horizontal measurements are made for the construction of additional coastal and marine boundaries. Tidal datums are also the basis for establishing privately owned land, government owned land, territorial sea, exclusive economic zone, and high seas boundaries. This is illustrated in the diagram below. Figure 3: Tidal Datum and Delineation of Maritime Zones Page 11 of 23

12 5.1 Tidal Datum For marine applications, a vertical datum is used as a reference from which to reckon heights or depths. It is called a tidal datum when defined in terms of a certain phase of the tide. Tidal datums are local datum and should not be extended into areas which have differing hydrographic characteristics with substantiating measurements. In order that they may be recovered when needed, such datums are referenced to fixed points known as bench marks. A tidal bench mark is one near a tide station to which the tide staff and tidal datums are referred. A primary bench mark is the principal mark of a group of tidal bench marks to which the tide staff and tidal datums are referred. Figure 4: Tidal Datum Tidal Datum is a reference elevation of the sea surface from which vertical measurements are made, such as depths of the ocean and heights of the land. The diagram above illustrates the various tidal datums, and the table below provides their definitions. Page 12 of 23

13 Table 1: Definitions of Tidal Datums Tidal Datum DHQ Mean Diurnal High Water Inequality DLQ Mean Diurnal Low Water Inequality DTL Diurnal Tide Level GT Great Diurnal Range HWI Greenwich High Water Interval LWI Greenwich Low Water Interval MHHW* Mean Higher High Water MHW Mean High Water MLLW* Mean Lower Low Water MLW Mean Low Water MN Mean Range of Tide MSL Mean Sea Level MTL Definition The difference in height of the two high waters of each tidal day for a mixed or semidiurnal tide. The difference in height of the two low waters of each tidal day for a mixed or semidiurnal tide. The arithmetic mean of mean higher high water and mean lower low water. The difference in height between mean higher high water and mean lower low water. The average interval (in hours) between the moon s transit over the Greenwich meridian and the following high water at a location. The average interval (in hours) between the moon s transit over the Greenwich meridian and the following low water at a location. The average of the higher high water height of each tidal day observed over the National Tidal Datum Epoch. For stations with shorter series, comparison of simultaneous observations with a control tide station is made in order to derive the equivalent datum of the National Tidal Datum Epoch. The average of all the high water heights observed over the National Tidal Datum Epoch. For stations with shorter series, comparison of simultaneous observations with a control tide station is made in order to derive the equivalent datum of the National Tidal Datum Epoch. The average of the lower low water height of each tidal day observed over the National Tidal Datum Epoch. For stations with shorter series, comparison of simultaneous observations with a control tide station is made in order to derive the equivalent datum of the National Tidal Datum Epoch. The average of all the low water heights observed over the National Tidal Datum Epoch. For stations with shorter series, comparison of simultaneous observations with a control tide station is made in order to derive the equivalent datum of the National Tidal Datum Epoch. The difference in height between mean high water and mean low water. The arithmetic mean of hourly heights observed over the National Tidal Datum Epoch. Shorter series are specified in the name; e.g. monthly mean sea level and yearly mean sea level. The arithmetic mean of mean high water and mean low water. Page 13 of 23

14 Mean Tide Level National Tidal Datum Epoch Station Datum Vertical Datum using Tidal Data The specific 19-year period over which tide observations are taken and reduced to obtain mean values (e.g., mean lower low water, etc.) for tidal datums. A fixed base elevation at a tide station to which all water level measurements are referred. The datum is unique to each station and is established at a lower elevation than the water is ever expected to reach. It is referenced to the primary bench mark at the station and is held constant regardless of changes to the water level gauge or tide staff. The datum of tabulation is most often at the zero of the first tide staff installed. This is vertical datum or water level from which all heights and depths are measured and used to produce a seamless surface by linking depths and elevations data in a common datum. This enables a user to integrate bathymetric and topographic coastal data from different sources having different reference datum. *Some locations have diurnal tides one high tide and one low tide per day. At most locations, there are semidiurnal tides the tide cycles through a high and low twice each day, with one of the two high tides being higher than the other and one of the two low tides being lower than the other Tidal Measurements Tidal datums are legal entities. Because of variations in gravity, semi-stationary meteorological conditions, semi-permanent ocean currents, changes in tidal characteristics, ocean density differences, and so forth, the sea surface (at any datum elevation) does not conform to a mathematically defined spheroid. Since the sea surface moves up and down from infinitely small amounts to hundreds of meters over periods of less than a second to millions of years, it is necessary to stop the vertical motion in order to have a practical reference. This reference elevation is obtained by averaging the observations of tides over a period of 19 years. Recorded hourly heights are averaged to determine the mean of the higher (or only) high tide of each tidal day (24.84 h), all the high tides, all the hourly heights, all the low tides, and the lower (or only) low tide. The length of the averaging segment is a specific 19 year, which averages all the tidal cycles through the regression of the Moon s nodes and the metonic cycle. (The metonic cycle is a time period of period of 235 lunar months, or about 19 years in the Julian calendar, at the end of which the phases of the moon recur in the same order and on the same days as in the preceding cycle.) In the United States the National Tidal Datum Epoch (NTDE) is a period of 19 years, from 1983 through 2001, adopted by the National Ocean Service as the period over which observations of tides are taken and reduced to average values for tidal datums. Page 14 of 23

15 5.1.2 Tidal and Geodetic Datum Relationships Geodetic datum relationships to tidal datums are established at tide stations by connecting tidal bench mark networks to the Spatial Reference System (SRS). The survey procedure using GRS Network may be used to make this connection. It is advised to make the connections to more than one bench mark, preferably to three marks, in order to confirm the connection and identify unstable bench marks. The elevation relationship between geodetic datums and tidal datums should not be extrapolated away from a particular location without correction or interpolation as the relationships vary with parameters such as variations in range of tide, bathymetry, topography, geoid variations, and vertical land movement Other Applications of Tidal Data Apart from coastline determination, tidal data has several important applications: Produce seamless surface for storm surge, inundation mapping, monitoring coastline erosion, coast planning, and coastal development management Provide a frame work to integrate and make available variety of geological and oceanographic distributed data sets of sediment type, boundary information, bottom feature, and habitat data Tidal modeling for water movement toward the coast Production of co-tidal chart Page 15 of 23

16 6 Content Model 6.1 Coastline Definition Though there are many legal and non-legal definitions for coastline, three coastline definitions as provided below. Definition 1 The intersection of the land with the water surface. The coastline shown on charts represents the line of contact between the land and a selected water elevation. In areas affected by tidal fluctuations, this line of contact is the mean high water line. In confined coastal waters of diminished tidal influence, the man water level line is used. Definition 2- The line of contact between the land and sea. On Coast and Geodetic Survey nautical charts and surveys the coastline approximates the mean high water line. Definition 3- General term including tidelands and navigable sea shores below the ordinary high water mark. The coastline geospatial data developer is encouraged to document any new definitions used for coastline data. 6.2 Coastline Classification Coastline type refers to the physical character of the upper intertidal zone or foreshore. This is the area where oil becomes stranded and where cleanup activities take place. The basic parameter that defines the coastline type is the substrate present in the inter-tidal zone primarily the presence or absence and size of sediments. This will affect the behavior, fate and persistence of stranded oil, and the types of cleanup methods that are appropriate. Standard classification of coastline type is very important for purposes of sensitivity mapping, contingency planning, developing spill response strategies and real time documentation of oiling conditions. Many beaches are actually assortments of different sediments, though they are categorized according to the primary substrate. Coastline classification schemes are numerous and a variety of classifications can be used. The following coastline type classification scheme shall be used: Sandy Beaches Sand-Gravel Beaches Rocky Beaches Man-Made Solid Structures Mud Tidal Flats Sand Tidal Flats Salt Marshes Page 16 of 23

17 Coral coastlines Mangrove coastlines Unclassified The coastline geospatial data developer is encouraged to thoroughly document any changes made in the above classification scheme. 6.3 Coastline Boundary The coastline boundary and its status from a legal or court perspective are recorded using Coastline Reference and Coastline Legal Status data elements. The domain values applicable to these two items are presented in the next section on Data Dictionary. The definitions for the domain values of Coastline Reference are provided in Appendix A: Information on Maritime Zones. Page 17 of 23

18 7 Data Dictionary This section defines attributes or elements that are common for coastline data development. A Coastline is the linear feature that represents the geometric coastline. Table 2: Recommended Attributes for Coastline Name Suggested Domain Values Definition Vertical_Datum Horizontal_Datum Date Time Tidal, Orthometric, Ellipsoidal One of the three classes of vertical datum: Tidal datum affected by the tidal epoch Orthometric datum tied to Ras Ghumays Ellipsoidal datum based on WGS84 Horizontal datum as per the AD-SDI Spatial Reference System Standard The calendar date entry of the original coastline data capture. The time of day of the original coastline data capture. H_Accuracy Horizontal positional accuracy value of measurement. V_Accuracy Vertical positional accuracy value of measurement. Distance Type Ground, Sea Level (geodetic), Grid Distance Describes the reference surface for the distance. Distance Reliability Describes the overall precision and accuracy (uncertainty) of the distance measurement components of Coastline. Source_Type Coastline Measurement Method Coastline_Definition Aerial Photography, LIDAR, Field Survey, User Defined From record document, digitized, computed, adjusted, field observation Definition 1, Definition 2, Definition 3, User Defined Information regarding the source or sources in creating the coastline data. Describes the process or procedure used to determine the coastline measurement information. The definition used for coastline data. Refer Section 6.1 Page 18 of 23

19 Coastline Type Coastline Reference Coastline Legal Status Coastline Comment Sandy Beaches, Sand-Gravel Beaches, Rocky Beaches, Man-Made Solid Structures, Mud Tidal Flats, Sand Tidal Flats, Salt Marshes, Coral coastlines, Mangrove coastlines, Unclassified Baseline, Territorial State, Contiguous Zone, Exclusive Economic Zone, Continental Shelf Limit Ambulatory, Tidal, Disputed, Adjudicated, Connecting Line, Computed, Duplicate, Archived Coastline Type refers to the physical character of the upper intertidal zone or foreshore. See Appendix A: Information on Maritime Zones for definitions. Identifies the coastline s status from a legal or court perspective. Additional information about the coastline that may be in the public record, but does conform to listed attributes for coastline. Page 19 of 23

20 Appendix A: Information on Maritime Zones United Nations Convention on the Law of the Sea (UNCLOS) set the limit of various areas, measured from a carefully defined baseline. A baseline is the line from which the seaward limits of a State's territorial sea and certain other maritime zones of jurisdiction are measured. Normally, a sea baseline follows the lowwater line (lowest astronomical tide) of a coastal State. When the coastline is deeply indented, has fringing islands or is highly unstable, straight baselines may be used. The various areas (shown in the figure) are as follows (1 nautical mile = kilometers): Figure 5: Schematic map of maritime zones Figure 6: Sea areas in international rights Page 20 of 23

21 Internal waters: Covers all water and waterways on the landward side of the baseline. The coastal state is free to set laws, regulate use, and use any resource. Foreign vessels have no right of passage within internal waters. Territorial waters: Out to 12 nautical miles from the baseline, the coastal state is free to set laws, regulate use, and use any resource. Contiguous zone: Beyond the 12 nautical mile limit there was a further 12 nautical miles or 24 nautical miles from the territorial sea baselines limit, the contiguous zone, in which a state could continue to enforce laws in four specific areas: pollution, taxation, customs, and immigration. Exclusive Economic Zone (EEZ): Extends from the edge of the territorial sea out to 200 nautical miles from the baseline. Within this area, the coastal nation has sole exploitation rights over all natural resources. Continental shelf: The continental shelf is defined as the natural prolongation of the land territory to the continental margin s outer edge, or 200 nautical miles from the coastal state s baseline, whichever is greater. Aside from its provisions defining ocean boundaries, the United Nations Convention establishes general obligations for safeguarding the marine environment and protecting freedom of scientific research on the high seas, and also creates an innovative legal regime for controlling mineral resource exploitation in deep seabed areas beyond national jurisdiction, through an International Seabed Authority and the Common heritage of mankind principle. Page 21 of 23

22 Appendix B: Opportunity to Create Coastline Data It is necessary to develop high-resolution topography and bathymetry data and produce accurate tidal models for the entire coastal region. The merged topography and bathymetry data can be used to create high-accuracy DEM data. Sea level can be raised or lowered to intersect DEM at any stage of the tide, thereby eliminating the task of manually delineating the coastline. Enhancing coastline data content and interoperability is technically feasible and timely in view of the several hydrographic, hydrologic and other related data acquisition projects and developments. The factors favorable for the determination of coastline data for the Emirate of Abu Dhabi include: Abu Dhabi Municipality s new base mapping project that is currently going on Improvements in 3D positioning using advanced GPS receivers and the GRS Network of Abu Dhabi Availability with Bayanat of one of the most advanced LIDAR instruments for acquiring coastal topography and bathymetry data Ongoing hydrographic data acquisition project by MSD mainly for preparing the nautical charts of UAE as well as to cater to the hydrographic data requirements of EAD, UPC, ADM, and other stakeholders DOT s requirements to map coastline on nautical charts intended to support safe marine navigation Abu Dhabi Municipality s requirement for Airborne LIDAR Bathymetry Survey for Abu Dhabi Coastline to develop an inundation model Abu Dhabi Municipality s requirement for establishing Coastal Hydrometeorological Stations MSD/Bayanat s plan for establishing a unified vertical datum across land and sea Increasing demand for coastal geospatial data by the AD-SDI community for use in various applications Page 22 of 23

23 References 1. National Shoreline Data Content Standard, Final Draft, FGDC Marine and Coastal Spatial Data Subcommittee, May United Nations Convention on the Law of the Sea (UNCLOS) - Part II: Territorial Sea and Contiguous Zone, 4. Standard Shoreline Types 5. Classification of Coastlines 6. Decision Support System for Marine Shoreline Assessment Page 23 of 23