Water covers 70% of the Earth's surface.

Hydrology is the study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources and environmental watershed sustainability. A practitioner of hydrology is a hydrologist, working within the fields of earth or environmental science, physical geography, geology or civil and environmental engineering.

Domains of hydrology include hydrometeorology, surface hydrology, hydrogeology, drainage basin management and water quality, where water plays the central role. Oceanography and meteorology are not included because water is only one of many important aspects within those fields.

Hydrological research can inform environmental engineering, policy and planning.

The term hydrology is from Greek: ὕδωρ, hydōr, "water"; and λόγος, logos, "study".

History of hydrology[link]

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Hydrology has been a subject of investigation and engineering for millennia. For example, about 4000 B.C. the Nile was dammed to improve agricultural productivity of previously barren lands. Mesopotamian towns were protected from flooding with high earthen walls. Aqueducts were built by the Greeks and Ancient Romans, while the history of China shows they built irrigation and flood control works. The ancient Sinhalese used hydrology to build complex irrigation works in Sri Lanka, also known for invention of the Valve Pit which allowed construction of large reservoirs, anicuts and canals which still function.

Marcus Vitruvius, in the first century B.C., described a philosophical theory of the hydrologic cycle, in which precipitation falling in the mountains infiltrated the Earth's surface and led to streams and springs in the lowlands. With adoption of a more scientific approach, Leonardo da Vinci and Bernard Palissy independently reached an accurate representation of the hydrologic cycle. It was not until the 17th century that hydrologic variables began to be quantified.

Pioneers of the modern science of hydrology include Pierre Perrault, Edme Mariotte and Edmund Halley. By measuring rainfall, runoff, and drainage area, Perrault showed that rainfall was sufficient to account for flow of the Seine. Marriotte combined velocity and river cross-section measurements to obtain discharge, again in the Seine. Halley showed that the evaporation from the Mediterranean Sea was sufficient to account for the outflow of rivers flowing into the sea.

Advances in the 18th century included the Bernoulli piezometer and Bernoulli's equation, by Daniel Bernoulli, the Pitot tube. The 19th century saw development in groundwater hydrology, including Darcy's law, the Dupuit-Thiem well formula, and Hagen-Poiseuille's capillary flow equation.

Rational analyses began to replace empiricism in the 20th century, while governmental agencies began their own hydrological research programs. Of particular importance were Leroy Sherman's unit hydrograph, the infiltration theory of Robert E. Horton, and C.V. Theis's Aquifer test/equation describing well hydraulics.

Since the 1950s, hydrology has been approached with a more theoretical basis than in the past, facilitated by advances in the physical understanding of hydrological processes and by the advent of computers and especially Geographic Information Systems (GIS).

Hydrologic cycle[link]

The central theme of hydrology is that water circulates throughout the Earth through different pathways and at different rates. The most vivid image of this is in the evaporation of water from the ocean, which forms clouds. These clouds drift over the land and produce rain. The rainwater flows into lakes, rivers, or aquifers. The water in lakes, rivers, and aquifers then either evaporates back to the atmosphere or eventually flows back to the ocean, completing a cycle. Water changes its state of being several times throughout this cycle.

Overview[link]

Branches of hydrology[link]

Chemical hydrology is the study of the chemical characteristics of water.
Ecohydrology is the study of interactions between organisms and the hydrologic cycle.
Hydrogeology is the study of the presence and movement of ground water.
Hydroinformatics is the adaptation of information technology to hydrology and water resources applications.
Hydrometeorology is the study of the transfer of water and energy between land and water body surfaces and the lower atmosphere.
Isotope hydrology is the study of the isotopic signatures of water.
Surface hydrology is the study of hydrologic processes that operate at or near Earth's surface.
Drainage basin management covers water-storage, in the form of reservoirs, and flood-protection.
Water quality includes the chemistry of water in rivers and lakes, both of pollutants and natural solutes.

Related topics[link]

Oceanography is the more general study of water in the oceans and estuaries.
Meteorology is the more general study of the atmosphere and of weather, including precipitation as snow and rainfall.
Limnology is the study of lakes. It covers the biological, chemical, physical, geological, and other attributes of all inland waters (running and standing waters, both fresh and saline, natural or man-made).^{[citation needed]}

Applications of hydrology[link]

• Determining the water balance of a region.
• Determining the agricultural water balance.
• Designing riparian restoration projects.
• Mitigating and predicting flood, landslide and drought risk.
• Real-time flood forecasting and flood warning.
• Designing irrigation schemes and managing agricultural productivity.
• Part of the hazard module in catastrophe modeling.
• Providing drinking water.
• Designing dams for water supply or hydroelectric power generation.
• Designing bridges.
• Designing sewers and urban drainage system.
• Analyzing the impacts of antecedent moisture on sanitary sewer systems.
• Predicting geomorphological changes, such as erosion or sedimentation.
• Assessing the impacts of natural and anthropogenic environmental change on water resources.
• Assessing contaminant transport risk and establishing environmental policy guidelines.

Hydrologic measurements[link]

Measurement is fundamental for assessing water resources and understanding the processes involved in the hydrologic cycle. Because the hydrologic cycle is so diverse, hydrologic measurement methods span many disciplines: including soils, oceanography, atmospheric science, geology, geophysics and limnology, to name a few. Here, hydrologic measurement methods are organized by hydrologic sub-disciplines. Each of these subdisciplines is addressed briefly with a practical discussion of the methods used to date and a bibliography of background information.

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Quantifying groundwater flow and transport^{[citation needed]}

• Aquifer characterization^{[citation needed]}
  • Flow direction
    • Piezometer - groundwater pressure and, by inference, groundwater depth (see: aquifer test)
    • Conductivity, storativity, transmisivity
    • Geophysical methods

• Vadose zone characterization^{[citation needed]}
  • Infiltration
    • Infiltrometer - infiltration
  • Soil moisture
    • Capacitance probe-soil moisture
    • Time domain reflectometer - soil moisture
    • Tensiometer - soil moisture
    • Solute sampling
    • Geophysical methods

Quantifying surface water flow and transport^{[citation needed]}

• Direct and indirect discharge measurements
  • Stream gauge - stream flow (see: discharge (hydrology))
  • Tracer techniques
  • Chemical transport
  • Sediment transport and erosion
  • Stream-aquifer exchange

Quantifying exchanges at the land-atmosphere boundary^{[citation needed]}

• Precipitation
  • Bulk rain events
    • Disdrometer - precipitation characteristics
    • Radar - cloud properties, rain rate estimation, hail and snow detection
    • Rain gauge - rain and snowfall
    • Satellite - rainy area identification, rain rate estimation, land-cover/land-use, soil moisture
    • Sling psychrometer - humidity
  • Snow, hail and ice
  • Dew, mist and fog
• Evaporation
  • from water surfaces
  • Evaporation -Symon's evaporation pan
  • from plant surfaces
  • through the boundary layer
• Transpiration
  • Natural ecosystems
  • Agronomic ecosystems
• Momentum
• Heat flux
  • Energy budgets

Uncertainty analyses

Remote sensing of hydrologic processes^{[citation needed]}

• Land based sensors
• Airborne Sensors
• Satellite sensors

Water quality

Main article: Water quality

^{[citation needed]}

• Sample collection
• In-situ methods
• Physical measurements (includes sediment concentration)
• Collection of samples to quantify Organic Compounds
• Collection of samples to quantify Inorganic Compounds
• Analysis of aqueous Organic Compounds
• Analysis of aqueous Inorganic Compounds
• Microbiological sampling and analysis

Integrating measurement and modeling

• Budget analyses
• Parameter estimation
• Scaling in time and space
• Data assimilation
• Quality control of data — see for example Double mass analysis

Hydrological prediction[link]

Observations of hydrologic processes are used to make predictions of the future behaviour of hydrologic systems (water flow, water quality). One of the major current concerns in hydrologic research is "Prediction in Ungauged Basins" (PUB), i.e. in basins where no or only very few data exist.

Statistical hydrology[link]

By analysing the statistical properties of hydrologic records, such as rainfall or river flow, hydrologists can estimate future hydrologic phenomena. When making assessments of how often relatively rare events will occur, analyses are made in terms of the return period of such events. Other quantities of interest include the average flow in a river, in a year or by season.

These estimates are important for engineers and economists so that proper risk analysis can be performed to influence investment decisions in future infrastructure and to determine the yield reliability characteristics of water supply systems. Statistical information is utilised to formulate operating rules for large dams forming part of systems which include agricultural, industrial and residential demands.

Hydrological modeling[link]

Hydrological models are simplified, conceptual representations of a part of the hydrologic cycle. They are primarily used for hydrological prediction and for understanding hydrological processes. Two major types of hydrological models can be distinguished:^{[citation needed]}

• Models based on data. These models are black box systems, using mathematical and statistical concepts to link a certain input (for instance rainfall) to the model output (for instance runoff). Commonly used techniques are regression, transfer functions, and system identification. The simplest of these models may be linear models, but it is common to deploy non-linear components to represent some general aspects of a catchment's response without going deeply into the real physical processes involved. An example of such an aspect is the well-known behaviour that a catchment will respond much more quickly and strongly when it is already wet than when it is dry..

• Models based on process descriptions. These models try to represent the physical processes observed in the real world. Typically, such models contain representations of surface runoff, subsurface flow, evapotranspiration, and channel flow, but they can be far more complicated. These models are known as deterministic hydrology models. Deterministic hydrology models can be subdivided into single-event models and continuous simulation models.

Recent research in hydrological modeling tries to have a more global approach to the understanding of the behaviour of hydrologic systems to make better predictions and to face the major challenges in water resources management.

Hydrologic transport[link]

Water movement is a significant means by which other material, such as soil or pollutants, are transported from place to place. Initial input to receiving waters may arise from a point source discharge or a line source or area source, such as surface runoff. Since the 1960s rather complex mathematical models have been developed, facilitated by the availability of high speed computers. The most common pollutant classes analyzed are nutrients, pesticides, total dissolved solids and sediment.

Hydrological organisations[link]

International research bodies[link]

• International Water Management Institute (IWMI)^[1]
• UNESCO-IHE Institute for Water Education^[2]

National research bodies[link]

• Centre for Ecology and Hydrology - UK ^[3]
• Centre for Water Science, Cranfield University, UK ^[4]
• eawag - aquatic research, ETH Zürich, Switzerland ^[5]
• Institute of Hydrology, Albert-Ludwigs-University of Freiburg, Germany^[6]
• U.S. Geological Survey^[7] - Water Resources of the United States^[8]
• NOAA's National Weather Service - Office of Hydrologic Development, USA^[9]
• US Army Corps of Engineers Hydrologic Engineering Center, USA^[10]
• Hydrologic Research Center - A Non-Profit Research Corporation, USA^[11]
• Economics of Water Resource Management from Improved Forecasting, NOAA Economics, USA^[12]
• University of Oklahoma- Natural Hazards and Disaster Center/USA ^[13]
• National Hydrology Research Center - Canada^[14]

National and international societies[link]

• Geologic Society of America (GSA) - Hydrogeology Division^[15]
• American Geophysical Union (AGU) - Hydrology Section^[16]
• National Groundwater Association (NGWA)^[17]
• American Water Resources Association^[18]
• Consortium of Universities for the Advancement of Hydrologic Science, Inc. (CUAHSI)^[19]
• International Association of Hydrological Sciences (IAHS)^[20][21]
• Statistics in Hydrology Working Group (subgroup of IAHS)^[22]
• British Hydrological Society ^[23]
• Russian Geographical Society (Moscow Centre)^[24] - Hydrology Commission^[25]
• International Association for Environmental Hydrology^[26]

Basin- and catchment-wide overviews[link]

• Connected Waters Initiative, University of New South Wales ^[27] — Investigating and raising awareness of groundwater and water resource issues in Australia

Research journals[link]

• Hydrological Processes, ISSN: 1099-1085 (electronic) 0885-6087 (paper), John Wiley & Sons
• Journal of Hydroinformatics, ISSN: 1464-7141, IWA Publishing
• Hydrology Research (formerly Nordic Hydrology), ISSN: 0029-1277, IWA Publishing
• Journal of Hydrologic Engineering, ISSN: 0733-9496, ASCE Publication

See also[link]

• Aquatic chemistry
• Civil engineering
• Climatology
• Environmental engineering
• Environmental engineering science
• Geomorphology
• Hydrography
• International Hydrological Programme
• Hydrology (agriculture)
• Water distribution on Earth
• Nash–Sutcliffe model efficiency coefficient
• WEAP (Water Evaluation And Planning) software to model catchment hydrology from climate and land use data

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (January 2011)

Notes[link]

Further reading[link]

• Introduction to Physical Hydrology, Martin Hendriks 2010. ISBN 9780199296842^{[Full citation needed]}
• Introduction to Hydrology, 4e. Viessman and Lewis, 1996. ISBN 0-673-99337-X^{[Full citation needed]}
• Handbook of Hydrology. ISBN 0-07-039732-5^{[Full citation needed]}
• Encyclopedia of Hydrological Sciences. ISBN 0-471-49103-9^{[Full citation needed]}
• Hydrologic Analysis and Design. McCuen, Third Edition, 2005. ISBN 0-13-142424-6^{[Full citation needed]}

External links[link]

Look up hydrology in Wiktionary, the free dictionary.

• Hydrology.nl – Portal to international hydrology and water resources
• International glossary of hydrology.
• Virtual campus in hydrology and water resources
• Decision tree to choose an uncertainty method for hydrological and hydraulic modelling
• Experimental Hydrology Wiki

v t e Water Outline Data page Properties Model Origin on Earth Distribution on Earth Hydrosphere Hydrobiology Hydrology Supply Management Water pollution Water resources Water cycle Category Commons WikiProject Water

v t e Subfields of physical geography Biogeography Climatology / Paleoclimatology Coastal geography Edaphology Geomorphology Glaciology Hydrology / Hydrography Landscape ecology Limnology Oceanography Palaeogeography Pedology/Soil science Quaternary science

This biographical article needs additional citations for verification. Please help by adding reliable sources. Contentious material about living persons that is unsourced or poorly sourced must be removed immediately, especially if potentially libelous or harmful. (February 2009)

Glenn Morrison

Personal information
Full name	Glenn Morrison
Nickname	Silver Surfer
Born	(1976-05-28) 28 May 1976 (age 36) Canterbury, New South Wales, Australia
Height	1.86 m (6 ft 1 in)
Weight	102 kg (16 st 1 lb) [1]
Playing information
Position	Second-row
Club
Years	Team	Pld	T	G	FG	P
1996–97	Balmain Tigers	41	7	0	0	28
1998–99	North Sydney Bears	42	9	0	0	36
2000–04	North Queensland	94	32	20	0	168
2005–06	Parramatta Eels	45	15	0	0	60
2007–09	Bradford Bulls	50	19	0	0	76
2010–2011	Wakefield Trinity Wildcats	44	9	0	0	36
	Total	316	91	20	0	404
Representative
Years	Team	Pld	T	G	FG	P
2001–2005	Country Origin	4	0	0	0	0
2011	Exiles	1	0	0	0	0
As of 14 November 2011
Source: Yesterday's Hero and Rugby League Project

Glenn Adam Morrison (born 28 May 1976 in Canterbury, New South Wales) is a former Australian professional rugby league player. He played for the Parramatta Eels, Balmain Tigers, North Sydney Bears, and the North Queensland Cowboys in the National Rugby League before moving to England to play for the Bradford Bulls and then the Wakefield Trinity Wildcats.

In 2001 Morrison was named the Cowboys' player of the year.^[2]

Glenn Morrison in action for Bradford

In January, 2007, Bradford Bulls Head Coach, Steve McNamara, appointed Morrison as vice-captain in his inaugural season at the club. That same year, Morrison made the Super League Dream Team. Morrison also won the T&A Player of the Year as well as the coaches' award, Players' Player of the Year and Supporters' Player of the Year titles in 2007

In 2008, Morrison made 733 tackles, the sixth highest in the entire competition.

After three years with the Bulls, Morrison signed with the Wakefield Trinity Wildcats for 2010 season. He has now signed for another year with the Wildcats.

In June 2011, Morrison was selected as a reserve in the inaugural England vs Exiles Origin match, at Headingley. He was promoted to the interchange bench after Warrington centre Matt King dropped out for personal reasons, and played for a large part of the game. Despite missing out on the Man of the Match trophy (picked up by Castleford Tigers stand off Rangi Chase), Morrison's performance was picked out as being amongst the best on the night.

• Country: Selected for Country Origin in 2001, 2003, 2004 and 2005.

Statistics[link]

Club career[link]

Year	Club	Apps	Pts	T	G	FG
1996	Balmain Tigers	21	16	4	-	-
1997	Balmain Tigers	20	12	3	-	-
1998	North Sydney Bears	22	12	3	-	-
1999	North Sydney Bears	20	24	6	-	-
2000	North Queensland Cowboys	20	4	1	-	-
2001	North Queensland Cowboys	23	52	13	-	-
2002	North Queensland Cowboys	15	60	7	16	-
2003	North Queensland Cowboys	22	36	7	4	-
2004	North Queensland Cowboys	14	16	4	-	-
2005	Parramatta Eels	22	36	9	-	-
2006	Parramatta Eels	23	24	6	-	-
2007	Bradford Bulls	24	40	10	-	-
2008	Bradford Bulls	8	8	2	-	-
2009	Wakefield Trinity Wildcats	23	28	7

Retirement[link]

On November 11, 2011, Morrison announced his immediate retirement from the game, acting on advice from health professionals, due to a serious shoulder injury. He remains at the Wakefield Trinity Wildcats, in the capacity of Assistant Coach.^[3]

References[link]

External links[link]

• Glenn Morrison Player Profile
• BULLS NET GLENN MORRISON
• Deacon to captain Bradford Bulls, Morrison vice-captain
• Morrison swaps Bulls for Wildcats