Definition of Hydrography

Hydrography is the branch of applied sciences which deals with the measurement and description of the physical features of oceans, seas, coastal areas, lakes and rivers, as well as with the prediction of their change over time, for the primary purpose of safety of navigation and in support of all other marine activities, including economic development, security and defence, scientific research, and environmental protection

he Importance of Hydrography

In addition to supporting safe and efficiient navigation of ships, hydrography underpins almost every other activity associated with the sea, including:

resource exploitation - fishing, minerals, ...environmental protection and managementmaritime boundary delimitationnational marine spatial data infrastructuresrecreational boating

maritime defence and securitytsunami flood and inundation modellingcoastal zone managementtourismmarine science

Objects of Hydrographic Surveying:

Hydrographic surveying are carried out for one or more of the following activities.

1 . Measurement of tides for sea coast work E.g. construction of sea defense works, harbors etc, for the establishment of leveling datam and for reducing sounding.2 . Determination of bed depth, by soundings• For navigation• Location of rocks, sand bars, navigation

light.• Fro location of under water works

volumes of under water excavation etc.• In connection with irrigation and land

drainage schemes.

3 . Determination of direction of current in connection with• The location of sewer any pipe or

channel that carry waste water out falls.

• Determination of area subject to silt and seour the eating of the place.

• Fornication purposes.• Measuremenment of quantity of

water and flow of water in connection of water schemes, Power scheme and flood controls.

Why we need Hydrographic Surveys - Uses & Applications of Hydrographic Survey• Offshore engineering and the shipping

industry have continued to expand.• Drilling rigs (extracting oil, gas etc from

deep sea) locating up to 125miles offshore, search for resources particularly oil and gas.

• Offshore islands are constructed of dredged material (to bring material form some where and dump there) to support marine structure.

1. The demand for recreational transportation ranges form large pleasure cruise ships to small sail bonds.

2. Cruise ships to small sail bonds. Hydrographic surveys are made to a quire and present data on oceans, lakes and harbors. It comprises all surveys made for

• The determination of shore lines, soundings (measurement of depth below the water level)

• Containerization has become an efficient and preferred method of cargo handling.• navigation and velocity as well as

characteristics of flow of water.• The location of lights rocks sand

balls, buoys ( anything that floats on the surface of water)

characteristics of bottoms, areas subjected to Suring and silting, depth available for

Sounding rod

6m

0.03m

0.02m

sextent

List of the equipment for hydrografic survey

1.Sounding boat2.Sounding rod or pole 3.Lead lines4.Sounding lead5.Sounding machine6.Fathometre or echo sounder7.Sextent8.Signal9.Cross rope