Hydrography is sometimes referred to as maritime cartography. In plain English, this refers to the process of making maps depicting bodies of water such as oceans or lakes.
The term is "representative sample." It is a subset of a population that accurately reflects the characteristics of the whole population it is meant to represent.
A landlocked country is a nation that does not have a coastline or access to open seas or oceans. These countries are surrounded by land and must rely on neighboring countries for trade and transportation through ports. Examples include countries like Switzerland, Bolivia, and Afghanistan.
There seems to be a typo in your question. However, if you meant "geography," it is the study of the Earth's physical features, climate, population, and the relationships between humans and their environment.
Another term for flatlands is "prairies."
The term is archipelago.
Correction: What is hydrographic datum? not "hydrography"
what is meant by the term catheterisation
What is meant by the term resistivity?
Explain what is meant by the term 'dementia.'
what is meant by the term identity politics
What is meant by the term organisation culture
What is meant by the term 'compaction'
What is meant by the term 'compaction'
what is meant by satyagraha
The National Hydrography Dataset for US Geological Survey serves many purposes. The NHD is a digital database of surface water features and it is used to make maps.
What is meant by the term 'client-server architecture'
Roughly, whether the water of interest is above mean sea level. Study of the Dead Sea and similar lakes also comes under the rubric "hydrography". 'Hydrography' is sometimes used synonymously with 'hydrology', but hydrography for the seas refers to the gathering of data to aid safe navigation, and as a development from that, wider uses to support exploration and development or environmental management. Whereas oceanography may be seen as a science for the better understanding of the natural world, hydrography can be regarded as applied science supporting economic development and protection of natural resources. There are areas of overlap: tidal studies, water quality, working from boats and ships. There are areas special to hydrography, such as geodesy (the shape of the Earth), datums (reference surfaces, both horizontal and vertical), applications to an individual country's mapping systems, measurement science (such as the technologies and deployment of survey instruments), boundary demarcation, and others.