This document summarizes key aspects of hydrographic surveying. It discusses measuring water depths through sounding, establishing horizontal and vertical controls, surveying shorelines, instruments used for sounding like sounding poles and echo sounders, reduction of soundings to a datum, teams involved in surveys, cartography methods to prepare nautical charts, key elements of nautical charts including datums and symbols, and common terms used in hydrography.

1. Hydrographic Survey Ildefonso, Sorbi

3. Deals with the physical features of the navigable portion of the earth’s surface and adjoining coastal areas.

4. Sounding –measurement of depth below the water surface

5. Applications of sounding:

6. Making nautical charts for safety of navigation

7. Development and engineering projects such as piers, dams and bridges

9. For large areas – 2nd or 3rd order triangulation

10. For smaller areas – transit-tape traverse

11. For small detached areas – stadia, graphical, plane table methods

12. For long narrow river – traverse on one side

13. For width >1km – traverse on both sides

14. Vertical Control

16. Syn. to Coastline

17. Line of contact between the land and the body of water

18. USC&GS uses the high water line

19. It consist of:

20. Determination or delineation of shorelines

21. Location of shore details and prominent features to which soundings may be connected

23. Location by Cross-Rope

24. Location by two angles from the shore

25. Location by Range and One angle from the shore

26. From the boat

27. Location by two angle from the boat

28. Location by Range and One angle from the boat

29. From both the shore and the boat

30. Location by One angle from the shore and from the boat

31. Location by Range and Time Intervals of the boat

32. Location by Intersecting Ranges

34. Parallel straight lines –> open coasts

35. Radiating lines –> small bays and islets

36. Circular curves or arcs –> isolated shoal

37. Spacing of Sounding Lines

39. Sounding Pole

40. The Leadline

41. Sounding Machines

42. Registering sheaves

44. Reduction of Sounding The reduced sounding are the reduced levels of the submarine surface in terms of the adopted datum A correction equal to the difference of level between the actual water level(gauge reading) and the datum(MLW/MLLW) is applied to the observed soundings.

45. Hydrographic Survey Team Officer-in-charge/Chief-of-party Left Angleman Right Angleman Recorder Fathometer attendant Leadsman Leadsman’s assistant Helmsman or Coxwain Engineer Additional general utility personnel

47. Nautical charts-> polyconic projection

48. Instruments used in the preparation of Nautical Charts

49. 3-arm protractor

50. Hairspring divider

51. Spacing divider

52. Proportional divider

53. Meter Bar

54. Opisometer/Map measure

56. Datums of a Nautical Chart

57. Horizontal Datum

58. Vertical Datum

59. Atlantic Ocean – Mean Low Water

61. Datum used

62. High, mean, low water lines

63. Soundings

64. Line of equal interpolated from the soundings called depth curves

65. Conventional symbols

66. All safety devices such as lighthouse, buoys etc.

68. Mechanical Solution

69. By tracing paper

70. By Station Pointer

71. Graphical Solution

72. Method 1

73. Method 2

75. Common Terms used in Hydrography Marginal continental features Bank Continental shelf Continental slope Insular shelf Insular slope Deep Sea Depression & Deep Sea Elevations Basin Deep Depression Depth Foredeep Trench Plateadu Ridge Seamount Swell

76. Common Terms used in Hydrography Embayments Bay Bright Cove Harbor Inlet Gulf Coastal Features Cape Coast High-water Line Island Islet Low-water line Point

77. Common Terms used in Hydrography Streams Bayou Brook and Run Creek Lagoon River Slough Caldron Canyon Seavalley Valley Submarine Elevations Bank Crest Dome Knoll Ledge Pinnacle Reef Shoal Spur