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Stream-aquifer System (stream-aquifer + system)

Distribution by Scientific Domains
Engineering100%

Selected Abstracts

Pumping-Induced Drawdown and Stream Depletion in a Leaky Aquifer System

GROUND WATER, Issue 2 2007
James J. Butler Jr
The impact of ground water pumping on nearby streams is often estimated using analytic models of the interconnected stream-aquifer system. A common assumption of these models is that the pumped aquifer is underlain by an impermeable formation. A new semianalytic solution for drawdown and stream depletion has been developed that does not require this assumption. This solution shows that pumping-induced flow (leakage) through an underlying aquitard can be an important recharge mechanism in many stream-aquifer systems. The relative importance of this source of recharge increases with the distance between the pumping well and the stream. The distance at which leakage becomes the primary component of the pumping-induced recharge depends on the specific properties of the aquifer, aquitard, and streambed. Even when the aquitard is orders of magnitude less transmissive than the aquifer, leakage can be an important recharge mechanism because of the large surface area over which it occurs. Failure to consider aquitard leakage can lead to large overestimations of both the drawdown produced by pumping and the contribution of stream depletion to the pumping-induced recharge. The ramifications for water resources management and water rights adjudication can be significant. A hypothetical example helps illustrate these points and demonstrates that more attention should be given to estimating the properties of aquitards underlying stream-aquifer systems. The solution presented here should serve as a relatively simple but versatile tool for practical assessments of pumping-induced stream-aquifer interactions. However, this solution should not be used for such assessments without site-specific data that indicate pumping has induced leakage through the aquitard. [source]

Drawdown and Stream Depletion Produced by Pumping in the Vicinity of a Partially Penetrating Stream

GROUND WATER, Issue 5 2001
James J. Butler Jr.
Commonly used analytical approaches for estimation of pumping-induced drawdown and stream depletion are based on a series of idealistic assumptions about the stream-aquifer system. A new solution has been developed for estimation of drawdown and stream depletion under conditions that are more representative of those in natural systems (finite width stream of shallow penetration adjoining an aquifer of limited lateral extent). This solution shows that the conventional assumption of a fully penetrating stream will lead to a significant overestimation of stream depletion (> 100%) in many practical applications. The degree of overestimation will depend on the value of the stream leakance parameter and the distance from the pumping well to the stream. Although leakance will increase with stream width, a very wide stream will not necessarily be well represented by a model of a fully penetrating stream. The impact of lateral boundaries depends upon the distance from the pumping well to the stream and the stream leakance parameter. In most cases, aquifer width must be on the order of hundreds of stream widths before the assumption of a laterally infinite aquifer is appropriate for stream-depletion calculations. An important assumption underlying this solution is that stream-channel penetration is negligible relative to aquifer thickness. However, an approximate extension to the case of nonnegligible penetration provides reasonable results for the range of relative penetrations found in most natural systems (up to 85%). Since this solution allows consideration of a much wider range of conditions than existing analytical approaches, it could prove to be a valuable new tool for water management design and water rights adjudication purposes. [source]

Quantifying the impact of groundwater discharge on the surface,subsurface exchange

HYDROLOGICAL PROCESSES, Issue 15 2009
Fulvio Boano
Abstract The exchange of oxygen and nutrients between the well-aerated stream water and the subsurface water is crucial for the biochemical conditions of the hyporheic zone. The metabolic activity of the hyporheic microorganisms controls the fate of nitrogen and phosphorus in the pore water, and influences the fate of these nutrients at the catchment scale. Unfortunately, the incomplete knowledge of the complex hydrodynamics of the coupled surface-subsurface flow field often hinders the understanding of the ecological relevance of the hyporheic processes. Here, we analyse the influence of groundwater discharge through the streambed on bedform-induced hyporheic exchange. A simple mathematical model of a coupled stream-aquifer system is developed in order to describe the essential feature of the surface-subsurface exchange. The most representative characteristics of the hyporheic exchange, e.g. the depth of the hyporheic zone - are parametrized in terms of a small number of easily measurable quantities. This information on the hyporheic flow field provides the fundamental basis for the study of the ecological function of the hyporheic zone. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Pumping-Induced Drawdown and Stream Depletion in a Leaky Aquifer System

GROUND WATER, Issue 2 2007
James J. Butler Jr
The impact of ground water pumping on nearby streams is often estimated using analytic models of the interconnected stream-aquifer system. A common assumption of these models is that the pumped aquifer is underlain by an impermeable formation. A new semianalytic solution for drawdown and stream depletion has been developed that does not require this assumption. This solution shows that pumping-induced flow (leakage) through an underlying aquitard can be an important recharge mechanism in many stream-aquifer systems. The relative importance of this source of recharge increases with the distance between the pumping well and the stream. The distance at which leakage becomes the primary component of the pumping-induced recharge depends on the specific properties of the aquifer, aquitard, and streambed. Even when the aquitard is orders of magnitude less transmissive than the aquifer, leakage can be an important recharge mechanism because of the large surface area over which it occurs. Failure to consider aquitard leakage can lead to large overestimations of both the drawdown produced by pumping and the contribution of stream depletion to the pumping-induced recharge. The ramifications for water resources management and water rights adjudication can be significant. A hypothetical example helps illustrate these points and demonstrates that more attention should be given to estimating the properties of aquitards underlying stream-aquifer systems. The solution presented here should serve as a relatively simple but versatile tool for practical assessments of pumping-induced stream-aquifer interactions. However, this solution should not be used for such assessments without site-specific data that indicate pumping has induced leakage through the aquitard. [source]

STREAMFLOW DEPLETION: MODELING OF REDUCED BASEFLOW ANI INDUCED STREAM INFILTRATION FROM SEASONALLY PUMPED WELLS,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 1 2001
Xunhong Chen
ABSTRACT: Numerical modeling techniques are used to analyze streamflow depletion for stream-aquifer systems with baseflow. The analyses calculated two flow components generated by a pumping well located at a given distance from a river that is hydraulically connected to an unconfined aquifer. The two components are induced stream infiltration and reduced baseflow; both contribute to total streamflow depletion. Simulation results suggest that the induced infiltration, the volume of water discharged from the stream to the aquifer, has a shorter term impact on streamflow, while the reduced baseflow curves show a longer term effect. The peak impacts of the two hydrologic processes on streamflow occur separately. The separate analysis helps in understanding the hydrologic interactions between stream and aquifer. Practically, it provides useful information about contaminant transport from stream to aquifer when water quality is a concern, and for areas where water quantity is an issue, the separate analysis offers additional information to the development of water resource management plan. [source]