What is hydrology, its importance and aims?

What is hydrology? The definition of hydrology is meaning science that gives information about nature of water, its phenomena and processes. The subject of hydrology studies all kinds of hydrosphere: oceans, rivers, seas, lakes, reservoirs, glaciers, wetlands, soil and groundwater, atmospheric water.

The main area of hydrology research is water regime and water balance, water cycle in nature, spatial and temporal variability and change of its elements under natural influence and anthropogenic factors. In practical application, hydrology is related to water industry, problems of rational using, protection of surface and groundwater from pollution and depletion, while developing methods of hydrological calculations and forecasts.

 Hydrology and Oceanology

Classification of hydrology science

According to the main study objects, hydrology is divided into land hydrology, glaciology, and oceanography.

Land hydrology

It is a science that studies the water surface of rivers, lakes, reservoirs, canals, wetlands and groundwater. Land hydrology includes:

  • hydrology of rivers or potamology;
  • limnology, which studies water bodies with sustained water exchange (lakes, ponds, reservoirs) and the whole complex is occurring physical, chemical, and biological processes;
  •  hydrogeology in the amount required to clarify the interaction processes of water, land, and groundwater surfaces.

Scope of oceanology

Wave, a large mass of waterOceanology is considering the World Ocean both as part of the hydrosphere, and as an integral planetary natural object that interacts with the atmosphere, lithosphere, continental runoff, and where in the complex interplay occur physical, geological, chemical, and biological processes.

Oceanology is based on actual measurement data of the depth, temperature, salinity, waves power, color and water clarity, dissolved of chemicals and compounds, various biological and other factors, that are based on the theoretical principles of physics, mathematics, chemistry, biology, using methods of analysis system.

Due to the widespread use of rivers and lakes for the purpose of irrigation, water supply, water transport, energy and many other purposes, a new direction has emerged and strengthened nowadays that is called engineering hydrology, which studies the quantitative and qualitative changes in water regime occurred in results of a particular hydraulic structure.


Glaciology is the science of the natural ice on the Earth's surface, atmosphere and lithosphere. It studies the regime and dynamics of their development, interaction with the environment, the role of ice in the Earth development. It also studies snow and ice resources, mass exchange of snow and glacier systems with the environment, deformation and movement of glaciers, avalanches, ice fields, ice sheets as the major reservoirs of fresh water of our planet, fluctuation of glaciers in the history of glaciation, engineering glaciology problems.

Development of science

The first rudiments of hydrology history appeared at the dawn of human history about 6,000 years ago in ancient Egypt. Egyptian priests used to have simple hydrological observations. They marked on rocks water levels during periods of the annual flooding of the Nile.

Definition of hydrology, the schemeIt took several thousand years for hydrology, which began with the observation of the Nile flood, could turn into an independent scientific discipline. An important milestone in the history of hydrology was the end of the 17th century. French scientist P. Perrault, and after him E. Marriott, measuring the precipitation and runoff amount in the basin of the Upper Seine, established quantitative ratios of the main water balance elements of the river basin. In the same period, the English astronomer E. Halley on the basis of experimental measurements of evaporation has shown by the example of the Mediterranean Sea, that the sea surface evaporation is much higher than the inflow of river water into it, and thus "closed" the water cycle scheme on Earth.

In the 19th century hydrology was still considered a part of physical geography, and sometimes it was attributed to hydraulic engineering or hydraulics. Only in the early 20th century the content of hydrology was determined as an independent science in some universities and technical schools in Germany, France, Russia, the United States, where special courses of hydrology took place.

The basis of detailed hydrological studies

Today the current stage of water resources development is impossible without detailed hydrological studies.

Groundwater is the object of studyFundamentals of hydrology are:

  1. Evaluation of water resources and water balance of the individual water bodies, or areas, or basin as a whole.
  2. Establishment of the calculated values of river runoff to design hydraulic structures.
  3. Calculations of evaporation from reservoirs and river basin water surfaces.
  4. Evaluation of temperature and ice regime of rivers and lakes.
  5. Study on the formation of river channels. Calculations of reservoir silting and study of their shores formation.
  6. Forecasts of all the major elements of the hydrological regime.
  7. Influence of hydraulic structures on the water flow to determine likely conditions in which these facilities will be used.
  8. The influence of engineering activity on the quantity and quality of river flow (flow control, land reclamation, clear cutting and plantations of forests).
  9. Study of reasons and sources of natural water pollution and the development of hydrological fundamentals to combat these undesirable effects on water resources.

What areas does hydrology help?

Lakes, rivers and other bodies of waterSince the quality of the environment is really related to water resources, the importance of hydrology is in the environment studding and searching for optimal methods of improving it. What areas does hydrology help?

  1. Industry and utilities are interested in assessing both the quantity and quality of consumed water, irrigated agriculture - the data on the regime of the water body from which the water withdrawal is performed.
  2. Any construction on the river shore (quays, piers, etc.), construction of bridges, pipeline crossings, and high-voltage power lines across rivers requires knowledge of water levels, ice phenomena, flow rates, river bed processes.
  3. River water transport needs the information about water levels, flow velocities, ice phenomena, river bed processes.
  4. Hydropower requires data on current and expected fluctuations in water flow, fisheries - physical and chemical characteristics of water.

Information of principles of hydrology studies is needed not only to meet the needs of water users, but it plays a great role in the solution of such problems as the protection of settlements and land from flooding (and not only in river areas, but also in the coastal regions). A particular relevance of knowledge of what is hydrology acquire research and forecasts of flooding on rivers, caused by rain or ice jams, and in estuaries and coastal areas - storm surges and tsunami waves.