What Percentage of Precipitation Falls Back Onto Land

Description of the Hydrologic Wheel

This is an education module almost the movement of water on the planet Earth. The module includes a discussion of h2o movement in the United states, and it likewise provides specific data nigh water movement in Oregon.
The scientific discipline in the field of physical geography that deals with the h2o bike is called hydrology. Information technology is concerned with the origin, distribution, and properties of water on the globe. Consequently, the water cycle is also called the hydrologic bike in many scientific textbooks and educational materials. Virtually people accept heard of the science of meteorology and many also know most the science of oceanography because of the exposure that each bailiwick has had on television set. People lookout TV weather personalities most every mean solar day. Celebrities such as Jacques Cousteau have helped to make oceanography a unremarkably recognized science. In a broad context, the sciences of meteorology and oceanography describe parts of a series of global physical processes involving h2o that are also major components of the scientific discipline of hydrology. Geologists describe another part of the concrete processes past addressing groundwater movement inside the planet’s subterranean features. Hydrologists are interested in obtaining measurable information and knowledge about the h2o cycle. Likewise of import is the measurement of the amount of h2o involved in the transitional stages that occur every bit the water moves from ane process within the cycle to other processes. Hydrology, therefore, is a broad science that utilizes information from a wide range of other sciences and integrates them to quantify the movement of water. The fundamental tools of hydrology are based in supporting scientific techniques that originated in mathematics, physics, engineering, chemistry, geology, and biology. Consequently, hydrology uses adult concepts from the sciences of meteorology, climatology, oceanography, geography, geology, glaciology, limnology (lakes), ecology, biology, agronomy, forestry, and other sciences that specialize in other aspects of the physical, chemical or biological surroundings. Hydrology, therefore, is i of the interdisciplinary sciences that is the basis for water resources development and h2o resource management.
The global h2o cycle tin can be described with nine major concrete processes which form a continuum of water motion. Complex pathways include the passage of h2o from the gaseous envelope effectually the planet called the temper, through the bodies of water on the surface of earth such as the oceans, glaciers and lakes, and at the same time (or more than slowly) passing through the soil and rock layers hole-and-corner. Later, the water is returned to the atmosphere. A key characteristic of the hydrologic wheel is that it has no beginning an it has no end. It can exist studied past starting at any of the post-obit processes: evaporation, condensation, precipitation, interception, infiltration, percolation, transpiration, runoff, and storage.
The information presented beneath is a profoundly simplified description of the major contributing physical processes. They include:
EVAPORATION

Evaporation occurs when the physical state of water is changed from a liquid country to a gaseous state. A considerable amount of oestrus, about 600 calories of energy for each gram of water, is exchanged during the change of state. Typically, solar radiations and other factors such as air temperature, vapor force per unit area, wind, and atmospheric pressure affect the amount of natural evaporation that takes place in whatever geographic expanse. Evaporation can occur on raindrops, and on free water surfaces such equally seas and lakes. It can even occur from water settled on vegetation, soil, rocks and snow. There is too evaporation caused past human activities. Heated buildings experience evaporation of water settled on its surfaces. Evaporated moisture is lifted into the atmosphere from the ocean, land surfaces, and water bodies as water vapor. Some vapor always exists in the atmosphere.
CONDENSATION

Condensation is the process by which water vapor changes it’due south physical land from a vapor, nearly commonly, to a liquid. H2o vapor condenses onto modest airborne particles to form dew, fog, or clouds. The most agile particles that class clouds are sea salts, atmospheric ions caused past lightning,and combustion products containing sulfurous and nitrous acids. Condensation is brought well-nigh past cooling of the air or past increasing the amount of vapor in the air to its saturation signal. When water vapor condenses back into a liquid state, the aforementioned large amount of oestrus ( 600 calories of energy per gram) that was needed to arrive a vapor is released to the surround.
Atmospheric precipitation

Precipitation is the process that occurs when any and all forms of h2o particles autumn from the atmosphere and achieve the ground. There are 2 sub-processes that cause clouds to release precipitation, the coalescence process and the water ice-crystal process. As water drops reach a disquisitional size, the drop is exposed to gravity and frictional drag. A falling drop leaves a turbulent wake backside which allows smaller drops to fall faster and to exist overtaken to join and combine with the lead drop. The other sub-process that can occur is the ice-crystal formation process. Information technology occurs when ice develops in cold clouds or in deject formations high in the atmosphere where freezing temperatures occur. When nearby water droplets approach the crystals some droplets evaporate and condense on the crystals. The crystals grow to a critical size and drop as snowfall or ice pellets. Sometimes, as the pellets fall through lower superlative air, they melt and change into raindrops.
Precipitated h2o may fall into a waterbody or information technology may fall onto state. It is so dispersed several means. The water can adhere to objects on or near the planet surface or it can be carried over and through the land into stream channels, or it may penetrate into the soil, or it may be intercepted by plants.
When rainfall is small and infrequent, a high percentage of precipitation is returned to the atmosphere by evaporation.
The portion of precipitation that appears in surface streams is called runoff. Runoff may consist of component contributions from such sources as surface runoff, subsurface runoff, or ground h2o runoff. Surface runoff travels over the ground surface and through surface channels to leave a catchment area called a drainage bowl or watershed. The portion of the surface runoff that flows over the land surface towards the stream channels is chosen overland flow. The full runoff confined in the stream channels is called the streamflow.
INTERCEPTION

Interception is the procedure of interrupting the movement of water in the chain of transportation events leading to streams. The interception can have place by vegetal cover or depression storage in puddles and in state formations such as rills and furrows.
When rain first begins, the h2o striking leaves and other organic materials spreads over the surfaces in a thin layer or it collects at points or edges. When the maximum surface storage adequacy on the surface of the fabric is exceeded, the material stores additional h2o in growing drops forth its edges. Eventually the weight of the drops exceed the surface tension and water falls to the footing. Wind and the touch on of pelting drops can likewise release the water from the organic material. The h2o layer on organic surfaces and the drops of h2o along the edges are likewise freely exposed to evaporation.
Additionally, interception of h2o on the footing surface during freezing and sub-freezing conditions tin be substantial. The interception of falling snowfall and ice on vegetation also occurs. The highest level of interception occurs when information technology snows on conifer forests and hardwood forests that have not yet lost their leaves.
INFILTRATION

Infiltration is the physical process involving motion of h2o through the boundary surface area where the atmosphere interfaces with the soil. The surface miracle is governed by soil surface conditions. Water transfer is related to the porosity of the soil and the permeability of the soil contour. Typically, the infiltration rate depends on the puddling of the water at the soil surface past the bear upon of raindrops, the texture and structure of the soil, the initial soil moisture content, the decreasing h2o concentration every bit the water moves deeper into the soil filling of the pores in the soil matrices, changes in the soil composition, and to the swelling of the wetted soils that in turn close cracks in the soil.
Water that is infiltrated and stored in the soil can too go the water that later is evapotranspired or becomes subsurface runoff.
PERCOLATION

Percolation is the motion of water though the soil, and it’south layers, past gravity and capillary forces. The prime moving forcefulness of groundwater is gravity. Water that is in the zone of aeration where air exists is called vadose water. H2o that is in the zone of saturation is called groundwater. For all practical purposes, all groundwater originates as surface water. Once undercover, the water is moved by gravity. The purlieus that separates the vadose and the saturation zones is called the water tabular array. Usually the management of water movement is changed from downwards and a horizontal component to the movement is added that is based on the geologic boundary weather condition.
Geologic formations in the globe’s crust serve as natural subterranean reservoirs for storing h2o. Others can also serve equally conduits for the move of h2o. Essentially, all groundwater is in motility. Some of it, nonetheless, moves extremely slowly. A geologic germination which transmits water from ane location to another in sufficient quantity for economic development is called an aquifer. The motility of water is possible because of the voids or pores in the geologic formations. Some formations conduct water back to the ground surface. A spring is a place where the water table reaches the ground surface. Stream channels can be in contact with an unconfined aquifer that approach the footing surface. Water may movement from the basis into the stream, or visa versa, depending on the relative water level. Groundwater discharges into a stream forms the base period of the stream during dry periods, especially during droughts. An influent stream supplies h2o to an aquifer while and effluent stream receives h2o from the aquifer.
TRANSPIRATION

Transpiration is the biological procedure that occurs mostly in the day. Water inside of plants is transferred from the constitute to the atmosphere as water vapor through numerous individual exit openings. Plants transpire to move nutrients to the upper portion of the plants and to cool the leaves exposed to the sun. Leaves undergoing rapid transpiration can be significantly cooler than the surrounding air. Transpiration is greatly affected by the species of plants that are in the soil and information technology is strongly affected past the amount of lite to which the plants are exposed. Water tin be transpired freely by plants until a water deficit develops in the constitute and information technology water-releasing cells (stomata) begin to close. Transpiration and so continues at a must slower rate. Only a small portion of the water that plants absorb are retained in the plants.
Vegetation generally retards evaporation from the soil. Vegetation that is shading the soil, reduces the wind velocity. Also, releasing water vapor to the atmosphere reduces the amount of direct evaporation from the soil or from snowfall or water ice encompass. The assimilation of water into establish roots, along with interception that occurs on plant surfaces offsets the general effects that vegetation has in retarding evaporation from the soil. The forest vegetation tends to have more moisture than the soil beneath the trees.
RUNOFF

Runoff is flow from a drainage basin or watershed that appears in surface streams. It by and large consists of the flow that is unaffected by artificial diversions, storages or other works that lodge might have on or in a stream channel. The flow is made upwards partly of precipitation that falls direct on the stream , surface runoff that flows over the land surface and through channels, subsurface runoff that infiltrates the surface soils and moves laterally towards the stream, and groundwater runoff from deep percolation through the soil horizons. Role of the subsurface flow enters the stream rapidly, while the remaining portion may take a longer menses earlier joining the h2o in the stream. When each of the component flows enter the stream, they form the total runoff. The full runoff in the stream channels is called streamflow and it is mostly regarded as direct runoff or base period.
STORAGE

At that place are three basic locations of water storage that occur in the planetary water bike. Water is stored in the temper; h2o is stored on the surface of the earth, and water stored in the ground.
Water stored in the atmosphere can be moved relatively quickly from 1 office of the planet to another part of the planet. The type of storage that occurs on the land surface and under the ground largely depend on the geologic features related to the types of soil and the types of rocks nowadays at the storage locations. Storage occurs as surface storage in oceans, lakes, reservoirs, and glaciers; hush-hush storage occurs in the soil, in aquifers, and in the crevices of rock formations.
The movement of water through the eight other major physical processes of the water cycle tin can be erratic. On average, h2o the temper is renewed every 16 days. Soil moisture is replaced about every year. Globally, waters in wetlands are replaced nearly every 5 years while the residence fourth dimension of lake water is about 17 years. In areas of low development past guild, groundwater renewal can exceed 1,400 years. The uneven distribution and motion of h2o over fourth dimension, and the spatial distribution of water in both geographic and geologic areas, can crusade farthermost phenomena such as floods and droughts to occur.

---

ESTIMATED


GLOBAL WATER CYCLE

              TYPE OF   LOCATION                  Book                Percentage OF Full
              
              WATER                      millions of  millions of            Book
              
              
                cu. miles    cu kilometer
              
              SALT H2o                                                       97.00
              
              
                oceans             314.ii         1308.0   (96.4%)
              
              
                saline bodies        ii.ane            eight.7   (0.6%)
              
              FRESH WATER                                                       2.ninety
              
              
                ice & snow           6.nine           28.7   (2.1%)
              
              
                lakes                0.5            ii.1   (0.15%)
              
              
                rivers               0.01           0.04  (0.003%)
              
              
                accessible
              
              
                groundwater          1.0            4.2   (0.31%)
              
              ATMOSPHERIC                                                      0.10
              
              
                ocean
              
              
                evaporation          0.1            0.42  (0.03%)
              
              
                land
              
              
                evaporation          0.05           0.21  (0.015%)
              
              
                precipitation
              
              
                over bounding main             0.09           0.37  (0.03%)
              
              
                precipitation
              
              
                over land            0.03           0.12  (0.01%)
              
              
                water vapor          0.005          0.02  (0.002%)
              
              ROUNDED Total                 326.00        1357.00              100.0
              
            

---

If a fifty-five gallon drum of h2o represented the total supply of water on the planet then:
a) the oceans would be represented by 53 gallons, one quart, 1 pint and 12 ounces;

b) the icecaps and glaciers would stand for 1 gallon, and 12 ounces;

c) the temper would contribute ane pint and 4.five ounces;

d) groundwater would add up to 1 quart, and 11.4 ounces;

due east) freshwater lakes would represent 1 half ounce;

f) inland seas and saline lakes would add upward to over i third of an ounce;

g) soil moisture and valdose h2o would total to about one 4th of an ounce;

h) the rivers of the world would merely add up to one-hundredth of an ounce (less than one ane-millionth of the water on the planet).

---

Water Upkeep IN THE UNITED STATES
The atmosphere above the 48 coterminous United States of America stores well-nigh 36.5 cubic miles per mean solar day of atmospheric water. A little over 10 percent or 3.9 cubic miles of it falls equally precipitation each twenty-four hour period. About ane,430 cubic miles of atmospheric precipitation fall over the 48 states annually. This volume would exist enough each year to cover usa with about 30 inches of h2o.
The greatest average yearly precipitation in the world of 460 inches (i,168 cm) occurs at Mt. Waialeale, Hawaii. The lowest average annual atmospheric precipitation of one.63 inches ( iv.one cm) in the United States occurred over a 42-year menses in Death Valley, California. The longest dry catamenia with no atmospheric precipitation in the United States occurred during a 767 day period from October three, 1912 to November eight, 1914 at Bagdad, California.
An boilerplate of lxx percent of the annual precipitation to the coterminous U.South. ( 1,001 cubic miles) evaporates back into the atmosphere from land and water surfaces and past transpiration from vegetation. The remaining 30 percentage of the annual precipitation ( 429 cubic miles) is transported through the other surface and subterranean processes of the water bike to a stream, lake, or ocean.
Groundwater storage in the coterminous U.s.a. has been estimated to be nearly 15,100 cubic miles both in the shallow groundwater (less than ii,600 anxiety deep) and an equal corporeality in the groundwater deeper than 2,600 feet. Soil moisture in the top 3 feet of soil is estimated to exist equivalent to about 150 cubic miles of water.
The United states has approximately 4,560 cubic miles of water stored in freshwater lakes. Although there are about 5,540 cubic miles of water are stored in the Bang-up Lakes alone, over 50 percent of the book is considered to be in the United States. Also, about 14 cubic miles are stored in salt lakes of the nation. In add-on, at that place is approximately 12 cubic miles of surface waters stored in stream channels in route to the oceans. Other sources of surface storage in the coterminous states include 16 cubic miles of frozen water in glaciers.
The stream flow volume that reach the oceans of the nation is about 1.12 cubic miles per day ( 409 cubic miles per year). The full combined surface and groundwater menstruation to the nation’southward oceans is 1.18 cubic miles per day. The Mississippi River alone contributes 0.34 cubic miles per day (annual natural runoff of 593,000 cubic anxiety per second).
There are approximately 2700 reservoirs and controlled natural lakes of more than 5,000 acre-feet in storage in the United states. The reservoirs provide 142 cubic miles of storage, almost xc% of which occurs in 600 of the largest reservoirs. Too, there are approximately 50,000 reservoirs ranging from fifty to five,000 acre-feet in storage. It is also estimated that at that place are about ii meg farm ponds in the United States. Well-nigh of the major reservoirs in the nation are owned by the public. The Agency of Land Management is the director of the nigh federal dams (over 750), but almost are small dams. The larger reservoirs are managed past the U.S. Regular army Corps of Engineers, the Bureau of Reclamation, and the Tennessee Valley Authorisation. The Corps has built and operates almost 600 dams and reservoirs ,the Agency of Reclamation operates nigh 300 dams and reservoirs, and the TVA has over 50 dams and reservoirs. Other federal agencies that manage small dams include the Us Forest Service with about 400, the Bureau of Indian Affairs with over 300, the National Park Service with over 260, the United states Fish and Wildlife Service with over 175, and the Department of Energy with about 30 dams.
WATER IN THE Land OF OREGON
Oregon is divided into two distinct rainfall zones by the Pour Range. The annual precipitation west of the Pour Mountains ranges from 40 to 140 inches. Eastward of the Cascades, precipitation ranges from ten to 20 inches per year. The boilerplate annual atmospheric precipitation for the entire country is 28 inches. The boilerplate annual runoff is about twenty inches. The state has a network of 112,000 miles of rivers and streams to accommodated the almanac runoff. There are over 365 waterfalls mapped in Oregon that are in the cascade and the cataract categories of waterfalls. Cascade waterfalls have small volumes of water with perpendicular movement of the flowing h2o often associated in a succession of stages. Cataract category waterfalls have big volumes of water that move perpendicularly. Over 120 geothermal hot springs in the state have been identified with h2o temperatures that are xv degrees F in a higher place the mean annual air temperature. The total groundwater supply in Oregon has non been quantified.
Oregon has an estimated available, almanac surface water supply of over 66 million acre-anxiety (19.5 cubic miles). Differences in the seasonal and geographic distribution of water resources throughout the state results in annual h2o shortages in many areas of the state, especially in eastern Oregon. Use of natural period of surface waters, surface storage in reservoirs, and basis water supplies from aquifers are used to meet the year effectually demands.
The major river affecting Oregon is the i,243 mile long Columbia River. It forms much of Oregon’south northern border with the country of Washington. One of the Columbia’s major tributaries, the Snake River forms a major portion of the eastern border of Oregon with Idaho and is the location of the 7,900 feet deep Hell’south Canyon. The Columbia River originates in adjacent states of Washington, Idaho, and Montana and in Canada. The boilerplate annual menstruation is 265,000 cubic feet per second. This volume represents 0.15 cubic miles per day.
Other major watersheds in Oregon can exist divided into 20 boosted basins. They include:

              
                N Coast Drainages                   Malheur
              
              
                Willamette                              Owyhee
              
              
                Sandy                                   Malheur Lake*
              
              
                Deschutes                               Klamath
              
              
                John Day                                Chetco
              
              
                Umatilla                                Rogue
              
              
                Grande Ronde                            S Coast Drainages
              
              
                Pulverisation                                  Umpqua
              
              
                Serpent                                   Mid-Coast Drainages
              
            

At that place are seven watersheds that empty into the Pacific Sea. Two of the basins (*) are closed basin and do not belch water to the ocean or to receiving streams. Eleven are interior basins that empty into receiving streams.
Oregon abounds with over 6,000 natural lakes, ponds, marshes, sloughs and reservoirs. Over 1,400 of them are named lakes. They have a combined expanse of 500,000 acres (781 foursquare miles). Hundreds of the lakes are unnamed. There are 13 Lost Lakes, 11 Bluish Lakes, 10 Clear Lakes and 10 Fish Lakes. They range in surface area size from a maximum of 90,000 acres (141 square miles) at Upper Klamath Lake to cattle pond, farm ponds, and manufactory ponds of less than one acre. Crater Lake is the deepest lake in the United States. It is 1,932 feet deep, with a capacity of xiv million acre-anxiety (4.14 cubic miles) and a surface expanse of 13,139 acres (20.5 square miles). Following heavy rainfall and runoff during in 1984, Malheur and Harney lakes in southeastern Oregon were joined together for several years. Malheur Lake and Harney Lake are once again separate lakes, but connected as role of a closed basin wetland system, with Malheur Lake being nearly 90,000 acres. The Malheur Lake circuitous is withal considered the largest natural body of h2o in Oregon. The 180,000 acres (281 foursquare miles) of the lake/wetland complex located in the airtight basin forms the largest freshwater marsh in the western contiguous U.s.. Other large lakes in Oregon include Waldo, Odell, and Wallowa lakes. More one-half of the lakes in the state are volcanic or glacial depressions located on the high meridian areas between the summits of the Cascade Range. Almost 100 of the natural lakes are clustered in the Wallowa Mountains of northeastern Oregon. Many other lakes are located between sand dunes well-nigh the Oregon shore. Many of the natural lakes throughout the state have had water control structures built at their outlets to enhance storage in the lakes and to control the release of stored water for downstream irrigation.
Oregon has more than 60 reservoirs with capacities of over 5,000 acre-feet each. The largest reservoir in the country is the Bureau of Reclamation’s Owyhee Lake in southeastern Oregon with over one one thousand thousand acre-anxiety ( 0.3 cubic miles) of storage. Near of the reservoirs in Oregon were built, at least partially, to store irrigation water. In that location are hundreds of modest single purpose reservoirs built by local irrigation companies. Rarer types of single purpose reservoirs include recreation reservoirs, fish and wildlife reservoirs, and h2o quality enhancement reservoirs.
Reservoirs are more often than not characterized by their project purposes. Water supply reservoirs are distinguished by large storage volumes that are capable of providing an expected annual supply of h2o and capable of outlasting most droughts. Irrigation reservoirs accept large conservation pools with maximum conservation pools at the beginning of the growing season and a minimum puddle during the nongrowing flavour. Flood control reservoirs have a small permanent pools with a large storage capacities to reduce downstream water levels cardinal locations on rivers. Another characteristic of flood control reservoirs is that they are generally drawndown as speedily every bit possible post-obit a high runoff outcome to reestablish their storage capabilities. A hydroelectric reservoir is characterized by storage and release properties that meet regional energy demands, specially during the winter or the summer. Re-regulation reservoirs are congenital below hydroelectric dams to stabilize water menstruation in rivers to reduce catamenia fluctuations between daily power generation periods. Headwater storage reservoirs for navigation purposes take large storage pools at the beginning of the dry season and they release enough h2o to support seasonal navigation traffic. Lock and dam reservoirs, however, back up waterborne navigation past creating slightly vary pools that extends upstream a considerable distance from the run-of-river projects.
US Regular army Corps of Engineers reservoirs are multiple purpose impoundments meeting several types of h2o resources needs such as flood control, hydroelectric power generation, navigation, irrigation, municipal and industrial h2o supply, water quality, fisheries, and recreation. The Portland District, Corps of Engineers built and operates three run-of-river reservoirs on the main stalk of the lower Columbia River, Bonneville, The Dalles, and John Day dams, that meet navigation, hydroelectric power, irrigation, fisheries, water quality and recreation needs. The Portland District also has built and operates 13 multiple purpose storage projects with a full chapters of 2,308,020 acre-feet of water at maximum conservation pool ( 0.68 cubic mile) in the Willamette River Basin. The district also stores 547,191 acre-feet of water (0.xvi cubic mile) at the maximum pools of the ii Rogue River Basin projects. Additionally, John Day Dam, on the Columbia River, has 534,000 acre-feet (0.16 cubic miles) of usable storage. Portland District’southward Willow Creek Dam, on the north primal Oregon tributary to the Columbia River, stores 6,249 acre-feet (0.002 cubic miles) at it’due south normal summer conservation pool level. Therefore, the total volume of water stored in Portland District reservoirs is equivalent to over 75 percent of the single daily flow of water from U.Southward. rivers into the oceans.
The scheduling of h2o storage and release from dams is office of a water resource engineering function called reservoir regulation.

Provided by Corps of Engineers – Portland District