USGS Report to congress: concepts for national assessment of water availability and use. Voinov A, Bousquet F Modelling with stakeholders. Environ Model Softw 25 11 — Walton WC Future water-level declines in deep sandstone wells in Chicago region. Ground Water 2 1 — Walton WC Groundwater resource evaluation. Zheng C, Wang PP An integrated global and local optimization approach for remediation system design.
Water Resour Res 35 1 — Ground Water 40 3 — Zhou Y A critical review of groundwater budget myth, safe yield and sustainability. J Hydrogeol — Download references. These concepts were developed through thoughtful conversations with a wide range of groundwater scientists, managers, decision support researchers, practitioners, and community stakeholders.
Conceptual development was initially completed as part of Dr. Lyndon B. You can also search for this author in PubMed Google Scholar. Correspondence to Suzanne A. Reprints and Permissions. Pierce, S. Aquifer-yield continuum as a guide and typology for science-based groundwater management. Hydrogeol J 21, — Download citation. Received : 07 December Accepted : 16 September Published : 18 October Issue Date : March Anyone you share the following link with will be able to read this content:.
Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative. Skip to main content. Search SpringerLink Search. Abstract Groundwater availability is at the core of hydrogeology as a discipline and, simultaneously, the concept is the source of ambiguity for management and policy.
References Ahlfeld DP, Mulligan AE Optimal management of flow in groundwater systems: an introduction to combining simulation models and optimization methods. Science — Article Google Scholar Doherty J Ground water model calibration using pilot points and regularization. Aquifer tests pumping tests , slug tests and constant-head tests are performed to estimate site-specific values for the hydraulic properties of aquifers and aquitards.
Under certain circumstances, however, site-specific hydraulic property data may not be available when needed. For example, reconnaissance studies or scoping calculations may require hydraulic property values before on-site investigations are performed. The following sections present representative hydraulic property values reported in the literature for horizontal and vertical hydraulic conductivity , storativity , specific yield and porosity.
Refer to these values if site-specific data are unavailable for your study or to check the results of field and laboratory tests conducted at an investigation site. Try out the interactive calculators for estimating hydraulic conductivity from grain size , specific storage and storativity!
Hydraulic conductivity is a measure of a material's capacity to transmit water. It is defined as a constant of proportionality relating the specific discharge of a porous medium under a unit hydraulic gradient in Darcy's law:.
Coefficient of permeability is another term for hydraulic conductivity. Note that hydraulic conductivity, which is a function of water viscosity and density, is in a strict sense a function of water temperature; however, given the small range of temperature variation encountered in most groundwater systems, the temperature dependence of hydraulic conductivity is often neglected. Transmissivity is the rate of flow under a unit hydraulic gradient through a unit width of aquifer of given saturated thickness.
The transmissivity of an aquifer is related to its hydraulic conductivity as follows:. The following tables show representative values of hydraulic conductivity for various unconsolidated sedimentary materials, sedimentary rocks and crystalline rocks from Domenico and Schwartz :. A number of empirical formulas, some dating back over a century, have been proposed which attempt to relate the hydraulic conductivity of an unconsolidated geologic material granular sediment or soil to its grain size distribution obtained from sieve analysis.
While these formulas can be useful as a first approximation of K , one should bear in mind that their generality is limited by a number of factors including the following:. It is important to perform regular and proper maintenance on your bore. This will help prevent clogging. In some areas fouling from iron bacteria may occur. This is commonly seen in bores along the coast near Warrnambool. Iron bacteria can be treated with chemicals. If you suspect you have an problem with iron bacteria in your bore please contact us.
In other cases the pumping activities of your neighbours can impact your bore. This is called interference and more can be found out on this subject on our What impacts groundwater levels page.
If you suspect bore interference is occurring, please contact us. The timing of any changes in yield is important as well.
Aquifers that are close to the surface generally show seasonal groundwater level patterns that are impacted by rainfall and pumping. During winter and spring when pumping is low and rainfall is high, groundwater levels and yields will be better.
In summer when rainfall is lower and pumping increases the groundwater levels may drop and impact your yield. To see how groundwater yield varies across the region and in different aquifer, visit our Southern Victoria map.
Open menu Close menu Explore our maps Groundwater basics What is groundwater? Where does groundwater come from and where does it go? How does groundwater move? Sustainable yield depends on the amount of capture, and whether this amount can be accepted as a reasonable compromise between a policy of little or no use, on one extreme, and the sequestration of all natural discharge, on the other extreme. A reasonably conservative estimate of sustainable yield would take all or suitable fractions of deep percolation.
Sustainable yield may also be expressed as a percentage of recharge. Sustainability may be fostered by enlightened management which seeks to capture rejected recharge, encourage clean artificial recharge, and limit negative artificial recharge. A holistic approach to groundwater sustainability considers the hydrological, ecological, socioeconomic, technological, cultural, institutional and legal aspects of groundwater utilization, seeking to establish a reasonable compromise between conflicting interests.
Communities are beginning to consider baseflow conservation as the standard against which to measure groundwater sustainability. In the end, sustainability reflects resource conservation policy; the more conservative a policy, the more sustainable it is likely to be. The water on the surface is called "surface water" and the water under the surface is called "ground water" Fig. They are both part of the hydrologic cycle, which is the continuous recirculatory movement of the waters of the Earth Fig.
In nature, surface water and ground water are related. Surface water can become ground water through infiltration, while ground water can become surface water through exfiltration. Therefore, surface water and ground water are inextricably connected; one cannot be considered or evaluated without regard to the other. While being part of the hydrologic cycle, the similarities between surface water and ground water appear to end there.
They can be shown to differ in two important ways: Surface water is completely renewable, usually within days or weeks, while ground water is not completely renewable, since it may take decades, centuries, or even longer time to renew, and Fresh surface water is scarce, particularly when compared with the large volumes of fresh ground water which are known to exist below the surface. Source: U. Geological Survey Fig.
With development pressures taxing the surface waters in many regions of the world, the trend has been to use ground water to help resolve perceived surface water scarcities. Without regulation, this trend places communities on a sure path toward groundwater mining.
Thus, the question of sustainability has arisen: To what extent can groundwater resources be exploited without compromising the principle of sustainable development? This study examines the historical development of groundwater use and of the limits placed thereon throughout the years.
The concepts of safe yield and sustainable yield are reviewed. The traditional concept of safe yield, which equates safe yield to annual recharge, is shown to be flawed because of its narrow focus. Sustainable yield extends beyond the conventional boundaries of hydrogeology, to encompass surface water hydrology, ecology, and other related topics.
The study concludes with a holistic approach to the sustainable yield of ground water. Attempts to limit groundwater pumping have been commonly based on the concept of safe yield, defined as the attainment and maintenance of a long term balance between the annual amount of ground water withdrawn by pumping and the annual amount of recharge. This definition is too narrow because it does not take into account the rights of groundwater-fed surface water springs and baseflow and groundwater-dependent ecosystems wetlands and riparian vegetation Sophocleous, Recently, the emphasis has shifted to sustainable yield Alley and Leake, ; Maimone, ; Seward et al.
Sustainable yield reserves a fraction of safe yield for the benefit of the surface waters. There is currently a lack of consensus as to what percentage of safe yield should constitute sustainable yield. The issue is complicated by the fact that knowledge of several related earth sciences is required for a correct assessment of sustainable yield.
Additionally, there are social, economic, and legal implications which have a definite bearing on the analysis. At the outset, a distinction is necessary between pristine and non-pristine groundwater reservoirs. Pristine reservoirs are those that have not been subject to human intervention; conversely, non-pristine reservoirs have a history of pumping.
Average annual recharge is normally taken over the period of record or some other suitably long period. Actual values of annual recharge may differ from the long-term average value. In pristine reservoirs, average natural recharge, which is a fraction of precipitation, is equal to average natural discharge, which feeds springs, streams, wetlands, lakes, and groundwater-dependent ecosystems.
Thus, net recharge, i. In pristine reservoirs, natural recharge is equal to natural discharge; thus, net recharge is zero. Natural discharge constitutes the baseflow of streams and rivers, and, in shallow groundwater reservoirs, it is the water that sustains certain types of vegetation, such as the hydrophytes, hygrophytes, and phreatophytes see Glossary.
Most groundwater is continuously flowing, subject to gravitational forces, eventually to join the surface waters Fig. It is only a matter of time before the natural recharge shows up as natural discharge, i. Three groundwater scenarios are possible: A pristine groundwater system, in equilibrium or steady state, in the absence of pumping; A developed groundwater system, in equilibrium or steady state, with moderate pumping at a fixed depth; and A depleted groundwater system, in nonequilibrium or unsteady state, with heavy pumping at an ever increasing depth.
In the pristine groundwater system Fig. Thus, natural recharge the blue block on the left equals natural discharge the blue block on the right Fig. In the developed groundwater system Fig. Likewise, captured discharge the brown block on the right is the decrease in discharge induced by pumping.
Then, residual discharge the blue block on the right is equal to natural recharge the blue block on the left minus captured discharge. Net recharge is equal to the sum of captured recharge plus captured discharge. Net recharge varies with the intensity of pumping; the greater the intensity of pumping, the greater the net recharge. Pumping in the developed groundwater system is equal to net recharge, i.
In addition to captured recharge and captured discharge, the depleted groundwater system Fig. Net recharge is equal to captured recharge plus captured discharge. Pumping in the depleted groundwater system is equal to net recharge plus captured storage Fig.
The greater the level of development, the greater the amounts of captured recharge and captured discharge, and, in the case of a depleted system, captured storage. The greater the captured discharge, the smaller the residual discharge. Since all aquifer discharge feeds surface water and evapotranspiration, it follows that intensive groundwater development can substantially affect local, subregional, or regional groundwater-fed surface water bodies and groundwater-dependent ecosystems.
He noted that water permanently extracted from an underground reservoir reduces by an equal quantity the volume of water passing from the basin by way of natural channels, i. To illustrate the existence of this natural discharge, Lee observed that heavy pumping would commonly result in the drying up of springs and wetlands.
Thus, he distinguished between a theoretical safe yield, equal to the natural recharge, and a practical safe yield, a lower value which takes into account the need to maintain a residual discharge Fig.
According to Lee, the residual discharge must be ascertained and deducted from the theoretical safe yield in order to obtain the practical safe yield.
Theis recognized that all ground water of economic importance is in constant movement through a porous rock stratum, from a place of recharge to a place of discharge Fig. He reasoned that under pristine conditions, aquifers are in a state of approximate dynamic equilibrium. Discharge by pumping is a new discharge superimposed on a previously stable system; consequently, it must be balanced by: an increase in natural recharge; a decrease in natural discharge; a loss of storage in the aquifer; or a combination thereof.
All ground water of economic importance is in constant movement through a porous rock stratum, from a place of recharge to a place of discharge. Significantly, Theis distinguished between natural recharge and available recharge.
Available recharge is the sum of unrejected and rejected recharge Fig. The unrejected recharge is the natural recharge; the rejected recharge is the portion of available recharge rejected by [portions of] an aquifer on account of being full at least part of the time.
To assure maximum utilization of the supply, Theis argued that groundwater development should tap primarily the rejected recharge and, secondarily, the evapotranspiration by non-productive vegetation.
Thus, he defined perennial safe yield as equal to the amount of rejected recharge plus the fraction of natural discharge that it is feasible to utilize. According to Theis , where rejected recharge is zero, the only way to replace the well discharge is by artificial recharge. The latter is the increase in recharge induced by human design. Kazmann argued that the concept of safe yield, when taken independent of considerations of regional hydrology, is a fallacious one, because it cannot be reconciled with the legal doctrine of appropriation.
All water coming from the ground must be replaced by water coming from the land surface in order for a perennial groundwater supply to be obtained. When all surface runoff in the area overlying an aquifer has been appropriated, a perennial supply cannot be obtained from the ground without encroaching on established rights. Echoing Theis , Kazmann saw artificial recharge as an effective technological fix to the safe yield quandary. Artificial recharge is useful where water is being lost by runoff in the same areas where ground water supplies are being depleted.
The need for recharge is apparent when springs start to dry up, pumping lifts increase, or shallow wells go dry. If these conditions persist for a reasonably long time, the ground water is probably being mined. In artificial recharge, the excess runoff is retained in locations where there are possibilities for increased underground storage. The usual methods employed are the improvement of natural openings and the impoundment of storm runoff for slower release.
The benefits can be local or regional Soil Conservation Service, Todd defined safe yield as the maximum quantity of water which can be extracted from an underground reservoir, yet still maintain the supply unimpaired.
Pumping in excess of safe yield leads to overdraft, which is a serious problem in certain groundwater basins in the United States and elsewhere. He argued that until overdrafts are reduced to safe yields, permanent damage or depletion of the ground water supplies is to be expected. He referred to permanent depletion as mining of groundwater because of its analogy to the mining of ores and petroleum. The concept of sustainable development emerged in the late s, forcing a reconsideration of safe yield practices.
Sustainable development must meet the needs of the present without compromising the ability of future generations to meet their own needs World Commission on Environment and Development, Implicit within this definition is the realization that natural resources could be exploited in an unsustainable fashion, i. Thus, the intergenerational ethical dilemma. Sustainability refers to renewable natural resources; therefore, sustainability implies renewability.
Since groundwater is neither completely renewable nor completely nonrenewable, it begs the question of how much groundwater pumping is sustainable. In principle, sustainable yield is that which is in agreement with sustainable development. This definition is clear; however, its practical application requires the understanding of complex interdisciplinary relationships, which have only recently been examined.
Alley et al. The definition of "unacceptable" is largely subjective, depending on the individual situation. For instance, what may be established as an acceptable rate of groundwater withdrawal with respect to changes in groundwater level, may reduce the availability of surface water, locally or regionally, to an unacceptable level. According to Alley et al.
Thus, safe yield is the maximum pumpage for which the consequences are considered acceptable.
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