Hydrology is the subject that studies the water distribution, movement and variation rules in the earth's atmosphere, on the surface and in the crustal and mutual action between water and environment, which belongs to the category of geophysical science. Through the test, analysis calculation and simulation, forecast the change and development of water quantity and water quality in the nature, to provide scientific basis for developing and using water resources, controlling flood and protecting the water environment, which belongs to a branch of geophysics and natural geography.
2. Research Areas
Hydrology has quite broad research fields. From the water in the atmosphere to the water in the ocean, from land surface water to groundwater, are all the objects of hydrological science research; mutual relations of hydrosphere with earth's natural circles like atmosphere, lithosphere and biosphere are also the study field of hydrology; hydrological science not only focuses on the research of water quantity but also on the research of water quality. Not only researches current hydrological instantaneous dynamic and life history, but also explores the global water history to predict its future trend of changes.
Land hydrology is a major component of hydrological science. Hydrological knowledge about the ocean and atmosphere has been classified into the category oceanography and atmospheric science.
3. Subject Content
Hydrology has closely relationship with meteorology, oceanography, geology, natural geography and other disciplines. General hydrology can be divided into hydrology meteorology, marine hydrology and land hydrology. Hydrology meteorology mainly studies water vapor change rules in the atmosphere, including atmospheric water cycle and water balance, water exchange of the underlying surface and atmosphere, which takes evaporation, condensation, precipitation as the main mode, belongs to the interdisciplinary subject of hydrology and meteorology. Marine hydrology mainly studies the hydrological phenomena in the ocean, including waves, tides and currents, belongs to one of the content of oceanography. Land hydrology mainly studies hydrological phenomena and movement patterns of various water bodies on the land. With the development of production and development needs and research work, it has formed a branch of the river water literature, limnology, glacial hydrology, groundwater hydrology. The content of land hydrology that directly serving for industry, agriculture, transportation and other production is called applied hydrology. Narrow hydrology usually refers to land hydrology and applied hydrology.
4. Research Methods
1) Cause analysis method. Taking collecting lots of measured data of hydrological station network and laboratory test data as the basis, study formation process, the physical mechanism and the mutual relationship of hydrological phenomenon, to establish quantitative relationship or hydrological model of hydrological phenomena and the influencing factors.
2) Mathematical statistics method. Hydrological phenomena are both deterministic and stochastic, some hydrological phenomenon can be regarded as a random event, with the principles and methods of probability theory and mathematical statistics, for some hydrological phenomena frequency analysis, calculating the hydrological data of various frequencies (return period).
3) Regional analysis. Climate and natural geographical conditions have regional distribution characteristics, hydrological phenomena also have a certain degree of similarity, so it can study hydrological elements classification and partition of feature values or the establishment of regional empirical formula, or draw a variety of characteristics value isoline graph and partitioning graph.
5. Research Objects
1) Dynamic system
2) Hydrological cycle
3) Internal cause
4) Various forms
6. Research Characteristics
2) Overall research
7. Hydrologic Branches
1) According to the research object: river hydrology, limnology hydrology, marsh hydrology, glacial hydrology, snow hydrology, hydrology meteorology, groundwater hydrology, regional hydrology and ocean hydrology, etc.
2) Hydrology gets information of water distribution in time and space and movement mainly through fixed-point observation, field survey and hydrological experiment (field experiment) means, and gradually forms hydrological science, hydrologic survey, hydrologic experiment, hydrological science, engineering hydrology, hydrological forecasting, agriculture hydrology, forest hydrology, urban hydrology.