hydrology is a branch of hydrological sciences, theories and methods it uses hydrology and related disciplines to study ways and means of solving various practical hydrological problems for construction of water conservancy, electricity, transportation, urban development and environmental protection to provide hydrological data and hydrological forecasting service design, provision of hydrological basis for agriculture, forestry and land management planning. With the development of productive forces. Issues hydrology applications are increasingly widespread use of a variety of professional, except for common problems besides. Also the focus of research for various professions, so as to gradually form a hydrologic survey, engineering water branch of literature, urban hydrology, agriculture and forestry, hydrology hydrology. The earliest literary achievements of water development projects, achieved the greatest. Hydrometry is the foundation of hydrology, hydrogeology and hydrology forecasting calculation is the main content of engineering hydrology.
hydrology application development can be traced to the 19th century. 1851 Mar Varney (T.J.Mulvaney) proposed inference formula to calculate the maximum flow of small watershed, hydrology from a qualitative description into the quantitative calculation stage. After that, Herschel (C.Herschel) and Freeman (J.R.Freeman) in 1880 and 1890 the first application of the duration curve. 1914 Hazen (A.Hazen) with normal probability paper lattice matching frequency curve. 1924 Foster (H.A.Foster) proposed a complete analysis of Pearson type Ⅲ frequency curve, so the theory and methods of mathematical statistics introduction of hydrology, laid the foundation for the study of the hydrological characteristics of random phenomena. 1932 Sherman (LKSher-man) proposed process line units, From 1934 to 1935, McCarthy (GTMcCorthy), who proposed the Muskingum flow algorithm, 1939 Horton (REHorton) established infiltration formula provides a method for the rainfall runoff and flood forecasting river basin. 1938 Snyder (F. F.Snyder) proposed a comprehensive line units, hydrological calculation has no record opens the way. These achievements hydrology to solve practical problems in various production and living conditions in preparation for the theory and methods; At this point, the initial formation of hydrology system.
40 years of the 20th century to the 1950s, the further development of hydrology. In 1945, carat (C. O. Clark) first proposed the concept of instantaneous unit 1957, Naci (J. E. Nash) completed the instantaneous unit method. In 1946 Polet Clain (Б. В. Поляков) pointed out that the Markov chain is available to describe the annual runoff series, so the theory of stochastic processes and methods introduced hydrology, enrich the content of hydrological statistics; in 1949, Kohler (MA of Kohler) and Linsley (RK Linsley) a first engagement shaft stormwater runoff multivariate correlation diagram, make the analysis of complex nonlinear relationship between the hydrological elements greatly simplified. After 50 years, the computer get in hydrology increasingly wide range of applications, hydrological mathematical models developed very quickly, probability theory and mathematical statistics, and automatic control and optimization of new achievements in theory, a random model, filtering techniques and systems analysis methods have introduced hydrology, remote sensing, nuclear technology provides a new means for the detection of hydrology, hydrology entered a new period of development.
After 50 years of the twentieth century, hydrology evolving discipline their own theories and methods, close contact engineering practice, has opened up new areas of research, such as water use, hydrological effects of human activities, the formation of a water engineering branch of literature, agriculture, hydrology, forest hydrology, urban hydrology and water medical literature.
After the 1950s, hydrology continuous development of the 20th century, has formed the following branches: ① engineering hydrology. The main contents are calculated hydrology, hydrological forecasting and hydraulic calculation. ② urban hydrology. The main content of the water resources assessment, urban groundwater rational development and urban land subsidence control, affect the process of urbanization and the formation of urban storm runoff floods, provide data for planning and design of urban flood control and drainage systems. ③ agricultural hydrology. The main soil moisture, soil evaporation, plant sporadic relationship with crop ecology, study the formation and characteristics of agricultural microclimate to coordinate water, soil, crops and the combined effects of weather; also studied the hydrological effects of various agricultural measures. ④ forest hydrology. The main impact of forest on precipitation, canopy interception, forest and woodland soil water infiltration dynamic process, forest evapotranspiration, runoff change the situation on the allocation of forest land, water protection role of forests. Hydrology issues
engineering hydrology The main research on the control of water and water engineering and management operation, etc., including the basic theory of hydrological analysis and calculation and hydrological forecasting and calculation methods. Hydrological forecast is divided into short-term and long-term forecasts. Short-term forecast to flood forecast as the most important, it asks the flow of real-time information based on wave propagation and flooding in the river area. Or information within the basin storm, rainfall runoff formation rule to calculate, publish flood forecasting, decision-making basis for the flood control operation. China mainly in parts of the northeast, northwest winter snow. Winter snow large river basins United States, the former Soviet Union and other countries, a large snowmelt intensity of snowmelt flooding form a great year, and thus the strength of factors can affect snowmelt and based on the amount of snow. Application of heat balance principle released snowmelt flood forecasting. Similarly, on the river ice conditions may include the date of Ice and freeze-up, ice thickness, kaihe termination date of Ice and ice conditions were forecast; special river, the Yellow River Loop segments such as China and Shandong section, because the river from the south North flow, upstream of the first kaihe easy formation of ice dams and dam backwater flooding, etc., need to publish a variety of river forecasting ice conditions. In addition, the need for irrigation and drought, soil moisture in dry season river water regime and farming areas (also called moisture) should also make a forecast as needed. A wider range of applications hydrological calculation. Design Flood hydraulic structures, design flood encounter the tributaries of annual runoff and annual runoff distribution, drainage, flood storage change, river sediment transport, erosion and changes of river channel changes, and reservoir backwater deposition and erosion downstream end, also within the scope of hydrologic calculation. Hydraulic calculation is mainly used for the calculation of reservoir normal water level, flood control level and in adjusting or regulating reservoir (or station) to optimize the scheduling, calculation of guaranteed output and installed capacity of hydropower stations. And calculates the base load and peak load, and for many years the average annual generating capacity in the power grid that it should bear the hydropower station, etc., which are an important part of the design and operation of hydropower stations.
Hydrometry Studies The main content is to collect hydrological data storage and provide production units. It includes layout, hydrological factors such as the hydrologic network of observation and finishing rainfall, water level, flow, ice conditions and other items published. Hydrological data not only for the various branches of engineering hydrology applications, but also for other professional branch of hydrology applications. Also provide basic data for national defense, water resources development, agricultural and industrial layout and land improvement.
urban hydrology a branch of applied hydrology. Research for the city's surface water, groundwater and water distribution during the year, water pollution and treatment, the possibility of rational exploitation of groundwater and groundwater recharge flood season, to prevent land subsidence city; effects of urbanization on storm flood, in order to planning of urban flood control and drainage design provides hydrological basis. By monitoring the city's sewage, wastewater treatment plants provide the basis for planning and diluted sewage diversion measures.
soil moisture in agricultural hydrology The main area of cultivation, soil evaporation, plant and distribute crop ecological relationships; groundwater depth research and crop root development and soil salinization of the relationship; study the formation and characteristics of the microclimate of agriculture, in order to more effectively coordinate the combined effects of water, soil, crop and microclimate. Thus reasonable irrigation, soil moisture and drought, waterlogging prevention and reduce soil erosion and provide scientific basis. Agriculture also studied hydrology hydrological effects of various agricultural measures.
Effects of forest hydrology The main forest on precipitation runoff, such as canopy interception, dynamic rule woodland soil and rainfall infiltration of water, evapotranspiration forest, forest and woodland on surface runoff, subsurface flow change litter and underground runoff distribution, so as to reveal the impact of forests on water balance factors; study forest water retention and its impact on a flood and continuous flooding, small floods and devastating floods; by comparison of abandoned woodland slope and soil erosion studies the role of soil and water conservation, the measures proposed to develop a scientific basis for soil and water conservation. Flood streams were exiled also use content of this timber forest hydrology.
hydrology is a branch of hydrological sciences, theories and methods it uses hydrology and related disciplines to study ways and means of solving various practical hydrological problems, hydrological design data and hydrological forecasting services for engineering construction of water, electricity, transportation, urban development and environmental protection, the provision of hydrological basis for agriculture, forestry and land management planning. Water use and hydrological effects of human activity is a new area of research hydrology. Groundwater hydrology is the use of the hydrological cycle and water balance principle of groundwater formation, movement, and hydrology branch of hydrological groundwater resources. It is the main research and groundwater origin, type, distribution, movement, hydrogeology and geological formation of the chemical composition of the environment are closely related, but studies have focused on the content. Since groundwater hydrology from the point of view of the hydrologic cycle to study the groundwater, so it climate science, literature of surface water, soil science are closely linked. Underground water quality evaluation, to make use of water chemistry and hydrology geochemistry knowledge. Further, the system analysis theory has been gradually adopted in the development of groundwater. Some of groundwater hydrology problems such as less rainfall, transformed the relationship between surface water and groundwater of the three, groundwater resources and their excellent staff development and management of research, many still at the exploratory stage. Lake hydrology is the study of lakes hydrological phenomena and utilization of water resources hydrology branch. Hydrology mixed with theoretical research foundation lake hydrology hydrological balance to be strengthened in order to clarify the lake hydrological phenomena internal links; improve water balance elements of observation and accuracy; promote the use of new technology; the lake as a system, to understand the relationship between all of these factors, environmental effects lakes, protection, development and utilization of water resources.