Interaction Of Ground Water And Surface Water In Different Landscapes Ground Pdf
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Groundwater is the water present beneath Earth 's surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the water table.
Groundwater is recharged from the surface; it may discharge from the surface naturally at springs and seeps , and can form oases or wetlands. Groundwater is also often withdrawn for agricultural , municipal , and industrial use by constructing and operating extraction wells.
The study of the distribution and movement of groundwater is hydrogeology , also called groundwater hydrology. Typically, groundwater is thought of as water flowing through shallow aquifers, but, in the technical sense, it can also contain soil moisture , permafrost frozen soil , immobile water in very low permeability bedrock , and deep geothermal or oil formation water. Groundwater is hypothesized to provide lubrication that can possibly influence the movement of faults.
It is likely that much of Earth 's subsurface contains some water, which may be mixed with other fluids in some instances. Groundwater may not be confined only to Earth. The formation of some of the landforms observed on Mars may have been influenced by groundwater. There is also evidence that liquid water may also exist in the subsurface of Jupiter 's moon Europa.
Groundwater is often cheaper, more convenient and less vulnerable to pollution than surface water. Therefore, it is commonly used for public water supplies.
For example, groundwater provides the largest source of usable water storage in the United States, and California annually withdraws the largest amount of groundwater of all the states. Many municipal water supplies are derived solely from groundwater. Use of groundwater has related environmental issues. For example, polluted groundwater is less visible and more difficult to clean up than pollution in rivers and lakes.
Groundwater pollution most often results from improper disposal of wastes on land. Major sources include industrial and household chemicals and garbage landfills , excessive fertilizers and pesticides used in agriculture, industrial waste lagoons, tailings and process wastewater from mines, industrial fracking, oil field brine pits, leaking underground oil storage tanks and pipelines, sewage sludge and septic systems.
Additionally, groundwater is susceptible to saltwater intrusion in coastal areas and can cause land subsidence when extracted unsustainably, leading to sinking cities like Bangkok and loss in elevation such as the multiple meters lost in the Central Valley of California. These issues are made more complicated by sea level rise and other changes caused by climate changes which will change precipitation and water scarcity globally. An aquifer is a layer of porous substrate that contains and transmits groundwater.
When water can flow directly between the surface and the saturated zone of an aquifer, the aquifer is unconfined. The deeper parts of unconfined aquifers are usually more saturated since gravity causes water to flow downward. The upper level of this saturated layer of an unconfined aquifer is called the water table or phreatic surface. Below the water table, where in general all pore spaces are saturated with water, is the phreatic zone.
Substrate with low porosity that permits limited transmission of groundwater is known as an aquitard. An aquiclude is a substrate with porosity that is so low it is virtually impermeable to groundwater. A confined aquifer is an aquifer that is overlain by a relatively impermeable layer of rock or substrate such as an aquiclude or aquitard.
If a confined aquifer follows a downward grade from its recharge zone , groundwater can become pressurized as it flows. This can create artesian wells that flow freely without the need of a pump and rise to a higher elevation than the static water table at the above, unconfined, aquifer. The characteristics of aquifers vary with the geology and structure of the substrate and topography in which they occur.
In general, the more productive aquifers occur in sedimentary geologic formations. By comparison, weathered and fractured crystalline rocks yield smaller quantities of groundwater in many environments. Unconsolidated to poorly cemented alluvial materials that have accumulated as valley -filling sediments in major river valleys and geologically subsiding structural basins are included among the most productive sources of groundwater.
The high specific heat capacity of water and the insulating effect of soil and rock can mitigate the effects of climate and maintain groundwater at a relatively steady temperature. For example, during hot weather relatively cool groundwater can be pumped through radiators in a home and then returned to the ground in another well.
During cold seasons, because it is relatively warm, the water can be used in the same way as a source of heat for heat pumps that is much more efficient than using air. The volume of groundwater in an aquifer can be estimated by measuring water levels in local wells and by examining geologic records from well-drilling to determine the extent, depth and thickness of water-bearing sediments and rocks.
Before an investment is made in production wells, test wells may be drilled to measure the depths at which water is encountered and collect samples of soils, rock and water for laboratory analyses.
Pumping tests can be performed in test wells to determine flow characteristics of the aquifer. Fluid flows can be altered in different lithological settings by brittle deformation of rocks in fault zones ; the mechanisms by which this occurs are the subject of fault zone hydrogeology. Groundwater makes up about thirty percent of the world's fresh water supply, which is about 0. This makes it an important resource that can act as a natural storage that can buffer against shortages of surface water , as in during times of drought.
Groundwater is naturally replenished by surface water from precipitation , streams , and rivers when this recharge reaches the water table. Groundwater can be a long-term ' reservoir ' of the natural water cycle with residence times from days to millennia ,   as opposed to short-term water reservoirs like the atmosphere and fresh surface water which have residence times from minutes to years.
The figure  shows how deep groundwater which is quite distant from the surface recharge can take a very long time to complete its natural cycle. By comparing the age of groundwater obtained from different parts of the Great Artesian Basin, hydrogeologists have found it increases in age across the basin.
Where water recharges the aquifers along the Eastern Divide , ages are young. As groundwater flows westward across the continent, it increases in age, with the oldest groundwater occurring in the western parts.
Recent research has demonstrated that evaporation of groundwater can play a significant role in the local water cycle, especially in arid regions. In the opposite photo, a centimeter-square reflective carpet, made of small adjacent plastic cones, was placed in a plant-free dry desert area for five months, without rain or irrigation. It is expected that, if seeds were put down before placing this carpet, a much wider area would become green. Certain problems have beset the use of groundwater around the world.
Just as river waters have been over-used and polluted in many parts of the world, so too have aquifers. The big difference is that aquifers are out of sight. The other major problem is that water management agencies, when calculating the " sustainable yield " of aquifer and river water, have often counted the same water twice, once in the aquifer, and once in its connected river. This problem, although understood for centuries, has persisted, partly through inertia within government agencies.
In Australia, for example, prior to the statutory reforms initiated by the Council of Australian Governments water reform framework in the s, many Australian states managed groundwater and surface water through separate government agencies, an approach beset by rivalry and poor communication. In general, the time lags inherent in the dynamic response of groundwater to development have been ignored by water management agencies, decades after scientific understanding of the issue was consolidated.
In brief, the effects of groundwater overdraft although undeniably real may take decades or centuries to manifest themselves. The science has been available to make these calculations for decades; however, in general water management agencies have ignored effects that will appear outside the rough timeframe of political elections 3 to 5 years. Marios Sophocleous  argued strongly that management agencies must define and use appropriate timeframes in groundwater planning. This will mean calculating groundwater withdrawal permits based on predicted effects decades, sometimes centuries in the future.
As water moves through the landscape, it collects soluble salts, mainly sodium chloride. Where such water enters the atmosphere through evapotranspiration , these salts are left behind. In irrigation districts, poor drainage of soils and surface aquifers can result in water tables' coming to the surface in low-lying areas. Major land degradation problems of soil salinity and waterlogging result,  combined with increasing levels of salt in surface waters.
As a consequence, major damage has occurred to local economies and environments. Four important effects are worthy of brief mention. First, flood mitigation schemes, intended to protect infrastructure built on floodplains, have had the unintended consequence of reducing aquifer recharge associated with natural flooding.
Second, prolonged depletion of groundwater in extensive aquifers can result in land subsidence , with associated infrastructure damage — as well as, third, saline intrusion. Another cause for concern is that groundwater drawdown from over-allocated aquifers has the potential to cause severe damage to both terrestrial and aquatic ecosystems — in some cases very conspicuously but in others quite imperceptibly because of the extended period over which the damage occurs. Groundwater is a highly useful and often abundant resource.
However, over-use, over-abstraction or overdraft , can cause major problems to human users and to the environment. The most evident problem as far as human groundwater use is concerned is a lowering of the water table beyond the reach of existing wells. As a consequence, wells must be drilled deeper to reach the groundwater; in some places e. Groundwater is also ecologically important.
The importance of groundwater to ecosystems is often overlooked, even by freshwater biologists and ecologists. Groundwaters sustain rivers, wetlands , and lakes , as well as subterranean ecosystems within karst or alluvial aquifers. Not all ecosystems need groundwater, of course. Some terrestrial ecosystems — for example, those of the open deserts and similar arid environments — exist on irregular rainfall and the moisture it delivers to the soil, supplemented by moisture in the air.
While there are other terrestrial ecosystems in more hospitable environments where groundwater plays no central role, groundwater is in fact fundamental to many of the world's major ecosystems.
Water flows between groundwaters and surface waters. Most rivers, lakes, and wetlands are fed by, and at other places or times feed groundwater, to varying degrees. Groundwater feeds soil moisture through percolation, and many terrestrial vegetation communities depend directly on either groundwater or the percolated soil moisture above the aquifer for at least part of each year.
Hyporheic zones the mixing zone of streamwater and groundwater and riparian zones are examples of ecotones largely or totally dependent on groundwater. Subsidence occurs when too much water is pumped out from underground, deflating the space below the above-surface, and thus causing the ground to collapse. The result can look like craters on plots of land.
This occurs because, in its natural equilibrium state, the hydraulic pressure of groundwater in the pore spaces of the aquifer and the aquitard supports some of the weight of the overlying sediments. When groundwater is removed from aquifers by excessive pumping, pore pressures in the aquifer drop and compression of the aquifer may occur. This compression may be partially recoverable if pressures rebound, but much of it is not.
When the aquifer gets compressed, it may cause land subsidence, a drop in the ground surface. For coastal cities, subsidence can increase the risk of other environmental issues, such as sea level rise. Seawater intrusion is the flow or presence of seawater into coastal aquifers; it is a case of saltwater intrusion.
It is a natural phenomenon but can be caused or worsened by anthropogenic factors, such as climate change caused sea level rise. Polluted groundwater is less visible, but more difficult to clean up, than pollution in rivers and lakes.
Major sources include industrial and household chemicals and garbage landfills , industrial waste lagoons, tailings and process wastewater from mines, oil field brine pits, leaking underground oil storage tanks and pipelines, sewage sludge and septic systems.
Material adapted from: Vandas, S. Water and the Environment, p. Click here to download the full handbook. Surface water and groundwater systems are connected in most landscapes. Streams interact with groundwater in three basic ways: streams gain water from inflow of groundwater through the streambed, streams lose water by outflow through the streambed, or they do both depending upon the location along the stream. It is the groundwater contribution that keeps streams flowing between precipitation events or after snowmelt. For a stream to gain water, the elevation of the water table in the vicinity of the stream must be higher than the streamwater surface.
Groundwater is the water present beneath Earth 's surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the water table. Groundwater is recharged from the surface; it may discharge from the surface naturally at springs and seeps , and can form oases or wetlands. Groundwater is also often withdrawn for agricultural , municipal , and industrial use by constructing and operating extraction wells.
Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. S oil, water, air, and plants are vital natural resources that help to produce food and fiber for humans. They also maintain the ecosystems on which all life on Earth ultimately depends. Soil serves as a medium for plant growth; a sink for heat, water, and chemicals; a filter for water; and a biological medium for the breakdown of wastes.
Jump to navigation. British poet W. This widespread problem of water pollution is jeopardizing our health. Unsafe water kills more people each year than war and all other forms of violence combined.
Learn how to incorporate these teaching materials into your class. Find out what's included with each module Learn how it can be adapted to work in your classroom See how your peers at hundreds of colleges and university across the country have used these materials to engage their students. This material was developed and reviewed through the InTeGrate curricular materials development process. This rigorous, structured process includes: team-based development to ensure materials are appropriate across multiple educational settings.
Water Pollution: Everything You Need to Know
Groundwater pollution also called groundwater contamination occurs when pollutants are released to the ground and make their way down into groundwater. This type of water pollution can also occur naturally due to the presence of a minor and unwanted constituent, contaminant or impurity in the groundwater, in which case it is more likely referred to as contamination rather than pollution. The pollutant often creates a contaminant plume within an aquifer. Movement of water and dispersion within the aquifer spreads the pollutant over a wider area. Its advancing boundary, often called a plume edge, can intersect with groundwater wells or daylight into surface water such as seeps and springs, making the water supplies unsafe for humans and wildlife. The movement of the plume, called a plume front, may be analyzed through a hydrological transport model or groundwater model.
Scientists and practitioners agree that integrated water resource management is necessary, with an increasing need for research at the regional scale 10 3 to 10 5 km 2. At this scale interactions between environmental and human systems are fully developed and global change is linked to local actions. The groundwater-surface water interaction GW-SW is of particular interest. Herein we review the scientific journal literature and examine GW-SW at the regional scale. We briefly review all existing literature on GW-SW, then summarise its characteristics at different scales and identify specific challenges of the regional scale. We explore whether GW-SW should be treated differently at regional and local scales. Regional GW-SW is rarely examined in experimental field studies, which almost exclusively cover small areas.
The interaction of ground water with surface water depends on the physiographic and climatic setting of the landscape. For example, a stream in a wet climate might receive ground-water inflow, but a stream in an identical physiographic setting in an arid climate might lose water to ground water.
How much do we depend on groundwater?
Our water resources face a host of serious threats, all of which are caused primarily by human activity. They include sedimentation, pollution, climate change , deforestation , landscape changes , and urban growth. One of the most serious threats to water resources is the degradation of ecosystems , which often takes place through changes to landscapes such as the clearance of forests, the conversion of natural landscapes to farmland, the growth of cities, the building of roads, and surface mining. Each type of change to a landscape will have its own specific impact, usually directly on natural ecosystems and directly or indirectly on water resources. Although it is difficult to integrate the intricacies of ecosystems into traditional assessment and management processes a holistic ecosystem approach to water management is strongly recommended.
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