2. 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

3. 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 management
maritime boundary delimitation
national marine spatial data infrastructures
recreational boating

4. maritime defence and security
tsunami flood and inundation modelling
coastal zone management
tourism
marine science
Objects of Hydrographic Surveying:
Hydrographic surveying are carried out for one or more of the following activities.

5. 1. Measurement of tides for sea coast work E. g
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.

6. 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.

7. 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.

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

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

10. 6m
0.03m
0.02m
Sounding rod

11. sextent

12. List of the equipment for hydrografic survey
Sounding boat
Sounding rod or pole
Lead lines
Sounding lead
Sounding machine
Fathometre or echo sounder
Sextent
Signal
Cross rope