Hydrology is a scientific study of the movement, distribution, and quality of water on Earth and other planets, including water cycles, water resources, and the sustainability of watersheds. A hydrologist is a hydrologist who works in the field of geography or the environment, physical geography, geology or civil and environmental engineering. Using various analytical methods and scientific techniques, they collect and analyze data to help solve water-related problems such as environmental conservation, natural disasters, and water management.
Hydrology is divided into surface water hydrology, groundwater hydrology (hydrogeology), and marine hydrology. Hydrological domains include hydrometeorology, surface hydrology, hydrogeology, wastewater management and water quality, where water plays a central role.
Oceanography and meteorology were excluded because water is just one of many important aspects of the field.
Hydrological research can inform environmental, policy and planning techniques.
The term hydrology comes from the Greek: ????, "hÃÆ'½d? R" which means "water"; and ?????, "lÃÆ'³gos" which means "learning".
Video Hydrology
Branch
- Chemical hydrology is the study of water chemistry characteristics.
- Ecohydrology is the study of the interactions between organisms and the hydrologic cycle.
- Hydrogeology is the study of the existence and movement of ground water.
- Hydroinformatics is an information technology adaptation for hydrological applications and water resources.
- Hydrometeorology is the study of the transfer of water and energy between the soil surface and the water surface and the lower atmosphere.
- Isotope hydrology is the study of isotopic signs of water.
- Surface hydrology is the study of hydrological processes operating on or near the surface of the Earth.
- Wastewater management includes water storage, in reservoirs, and flood protection.
- Water quality includes water chemistry in rivers and lakes, both pollutants and natural solutes.
Maps Hydrology
Apps
- Calculation of rainfall.
- Calculates surface runoff and precipitation.
- Determine the water balance of a region.
- Determine the balance of agricultural water.
- Designing riparian restoration projects.
- Reduce and predict risks of floods, landslides, and droughts.
- Real-time flood and flood warning estimates.
- Designing irrigation schemes and managing agricultural productivity.
- Part of the hazard module in disastrous modeling.
- Providing drinking water.
- Designing a dam for water supply or hydroelectricity.
- Designing a bridge.
- Designing sewers and city drainage systems.
- Analyze the impact of previous moisture on sanitary sewer systems.
- Predict geomorphological changes, such as erosion or sedimentation.
- Assess the impacts of natural and anthropogenic environmental changes on water resources.
- Assess risks of contaminant transportation and make environmental policy guidelines.
- Estimate the potential of water resources from the river basin.
History
Hydrology has been the subject of investigation and engineering for thousands of years. For example, about 4000 BC Nile is dammed to increase agricultural productivity of barren land before. Mesopotamian cities are protected from flooding with high earthen walls. Waterways were built by Greeks and Ancient Romans, while Chinese history shows that they built irrigation and flood control work. Ancient Sinhala uses hydrology to build complex irrigation works in Sri Lanka, also known for the Pit Pit discovery that allows the construction of large dams, anicuts and functional canals.
Marcus Vitruvius, in the first century BC, described the philosophical theory of the hydrological cycle, where rain falling in the mountains infiltrated the Earth's surface and caused streams and springs in the lowlands. By adopting a more scientific approach, Leonardo da Vinci and Bernard Palissy independently achieved an accurate representation of the hydrologic cycle. New in the 17th century the hydrological variables began to be quantified.
The pioneers of modern hydrological science include Pierre Perrault, Edme Mariotte, and Edmund Halley. By measuring rainfall, runoff, and drainage areas, Perrault shows that rainfall is sufficient to account for the flow of the Seine. Marriotte combines the speed and cross-sectional measurements of the river to get the discharge, again on the Seine. Halley points out that evaporation from the Mediterranean Sea is sufficient to explain the flow of rivers that flow into the sea.
Progress in the 18th century included Bernoulli piezometer and Bernoulli equation, by Daniel Bernoulli, and Pitot tube, by Henri Pitot. The 19th century saw developments in groundwater hydrology, including Darcy's law, the Dupuit-Thiem well formula, and Hagen-Poiseuille capillary flow equation.
Rational analysis began to replace empiricism in the 20th century, while government agencies started their own hydrological research program. The most important is the hydrograph unit Leroy Sherman, infiltration theory Robert E. Horton, and C.V. Aquifer tests/aquifer equations describe hydraulics well.
Since the 1950s, hydrology has been approached on a more theoretical basis than in the past, facilitated by advances in physical understanding of hydrological processes and by the emergence of computers and especially geographic information systems (GIS). (See also GIS and hydrology)
Themes
The main theme of hydrology is that water circulates throughout the Earth through different paths and at different levels. The most obvious picture of this is the evaporation of water from the ocean, which forms clouds. These clouds float above the ground and produce rain. Rain water flows into lakes, rivers, or aquifers. Water in lakes, rivers, and aquifers then evaporates back into the atmosphere or eventually flows back into the ocean, completing the cycle. Water changes its state several times throughout this cycle.
Areas of research in hydrology concern the movement of water among various states, or within a particular country, or only measure the number in these countries in a particular region. The hydrological sections concern the development methods to measure the flow or amount of water directly, while others concern the modeling of these processes either for scientific knowledge or for making predictions in practical applications.
Ground water
Groundwater is water beneath the earth's surface, often pumped for drinking water. Groundwater hydrology (hydrogeology) considers measuring groundwater flow and transport of solutes. Problems in describing saturation zones include the characterization of aquifers in terms of flow direction, groundwater pressure and, by inference, the depth of groundwater (see aquifer test). Measurements here can be done using a piezometer. The aquifers are also described in terms of hydraulic conductivity, storativity and transmissivity. There are a number of geophysical methods to characterize the aquifers. There is also a problem in characterizing the vadose zone (unsaturated zone).
Infiltration
Infiltration is the process by which water enters the soil. Some water is absorbed, and the rest seeps into the water table. The infiltration capacity, the maximum rate at which the soil can absorb water, depends on several factors. The saturated layer provides a resistance that is proportional to its thickness, while the added depth of water above the soil provides a driving force (hydraulic head). Dry soil may allow rapid infiltration by capillaries; this force decreases as the soil becomes wet. Compaction reduces porosity and pore size. The surface cover increases capacity by slowing runoff, reducing compaction and other processes. Higher temperatures reduce viscosity, increase infiltration.
Soil moisture
Soil moisture can be measured in various ways; with probe capacitance, time domain reflectometer or Tensiometer. Other methods include dissolved sampling methods and geophysics.
Surface water flow
Hydrology considers measuring surface water flow and solute transport, although stream processing in large rivers is sometimes regarded as a different topic of hydraulics or hydrodynamics. Surface water flows may include both flow in the recognizable river channel and vice versa. Methods for measuring the flow once the water has reached the river include flow meters (see: discharge), and tracking techniques. Other topics include chemical transportation as part of surface water, sediment transport and erosion.
One important area of ​​hydrology is the exchange between rivers and aquifers. The interaction of groundwater/surface water in streams and aquifers can be complex and the direction of water flux (to surface waters or into aquifers) may vary spatially along the flow channel and over time at a particular location, depending on the relationship between the flow stage and groundwater level.
Rainfall and evaporation
In some considerations, hydrology is considered to be the beginning of the terrestrial-atmosphere boundary and therefore it is important to have adequate knowledge of precipitation and evaporation. Precipitation can be measured in various ways: a disdrometer for precipitation characteristics on a good time scale; radar for cloud properties, estimation of rain rates, hail and snow detection; rain gauges for accurate accurate rainfall and snowfall measurements; satellite for rainfall identification, rainfall estimate, land cover/land use, and soil moisture, for example.
Evaporation is an important part of the water cycle. Partly influenced by moisture, which can be measured by a sling psychrometer. It is also influenced by the presence of snow, hail and ice and can be associated with dew, fog and fog. Hydrology considers the evaporation of various forms: from surface water; as transpiration of the plant surface in the natural ecosystem and agronomy. The direct measurement of evaporation can be obtained by using a Simon's vaporizer.
Detailed studies of evaporation involve consideration of boundary layers as well as momentum, heat flux and energy budget.
Remote sensing
Remote sensing of the hydrological process can provide information about the location where in situ sensors may be unavailable or rare. It also allows the observation of large spatial extents. Many variables that form a terrestrial water balance, such as surface water storage, soil moisture, precipitation, evapotranspiration, and snow and ice, can be measured using remote sensing at various spatial-temporal resolutions and accuracy. Remote sensing sources include ground-based sensors, air sensors and satellite sensors that can capture microwave, thermal and near-infrared data or use lidar, for example.
Water quality
In hydrology, the study of water quality concerns organic and inorganic compounds, and both soluble and sediment materials. In addition, water quality is affected by the interaction of dissolved oxygen with organic matter and various chemical transformations that may occur. Water quality measurements may involve in-situ methods, where analysis is done on-site, often automatically, and laboratory-based analysis and may include microbiological analysis.
Integrating measurement and modeling
- Budget analysis
- Estimated parameters
- Scaling in space and time
- Data assimilation
- Data quality control - see for example Multiple mass analysis
Prediction
Observation of hydrological processes is used to make predictions of future behavior of hydrological systems (water flow, water quality). One of the main concerns currently in hydrological research is "Prediction in Ungauged Basins" (PUB), ie in basins where there is no or little data available.
Hydrological statistics
By analyzing the statistical properties of hydrological records, such as rainfall or river flow, hydrology can predict future hydrological phenomena. When making judgments about how often relatively rare events will occur, the analysis is made in terms of return periods of such events. Other interest rates include the average flow in the river, within a year or by season.
These estimates are important for engineers and economists so that appropriate risk analysis can be done to influence investment decisions in future infrastructure and to determine the reliability characteristics of the results of the water supply system. Statistical information is used to formulate operating rules for large dams that form part of the system covering agriculture, industry and housing demands.
Modeling
The simplified hydrological model, the conceptual representation of part of the hydrological cycle. They are primarily used for hydrological prediction and for understanding hydrological processes, in the general field of scientific modeling. The two main types of hydrological models can be distinguished:
- Model by data. These models are black box systems, using mathematical and statistical concepts to connect specific inputs (eg rainfall) to model output (eg runoff). Commonly used techniques are regression, transfer function, and system identification. The simplest of these models may be linear models, but it is common to deploy non-linear components to represent some common aspects of the catch response without going deeply into the actual physical processes involved. An example of such an aspect is the well-known behavior that catches will respond faster and stronger when it's wetter than when it dries.
- Model based on process description. These models try to represent the physical processes observed in the real world. Typically, the model contains surface runoff representations, subsurface flow, evapotranspiration, and channel flow, but they can be much more complicated. These models are known as deterministic hydrological models. Deterministic hydrological models can be divided into single-event models and continuous simulation models.
Recent research in hydrological modeling tries to have a more global approach to understanding the behavior of hydrological systems to make better predictions and to face key challenges in water resource management.
Transportation
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