Hydrography is a branch of survey which deals with the measurement and description of the terrain features of ocean, seas, coastal area, lake and Rivers. Many utilities such as drainage or irrigation pipe lines, construction of ports, developments of coastal areas are benefited with such survey. it cover nearest land of wet source and inside the water up to a particular depth. Now a days the requirement of hydrographic survey is very familiar because the we are now "interested to investment" in water than the land.
Fortunately , new survey technologies have improved the precision to which modern hydrographic surveys can be conducted.