Article

Representing Pump-Capacity Relations in Groundwater Simulation Models

US Geological Survey, 431 National Center, Reston, VA 20192, USA.
Ground Water (Impact Factor: 1.95). 09/2009; 48(1):106-10. DOI: 10.1111/j.1745-6584.2009.00619.x
Source: PubMed

ABSTRACT The yield (or discharge) of constant-speed pumps varies with the total dynamic head (or lift) against which the pump is discharging. The variation in yield over the operating range of the pump may be substantial. In groundwater simulations that are used for management evaluations or other purposes, where predictive accuracy depends on the reliability of future discharge estimates, model reliability may be enhanced by including the effects of head-capacity (or pump-capacity) relations on the discharge from the well. A relatively simple algorithm has been incorporated into the widely used MODFLOW groundwater flow model that allows a model user to specify head-capacity curves. The algorithm causes the model to automatically adjust the pumping rate each time step to account for the effect of drawdown in the cell and changing lift, and will shut the pump off if lift exceeds a critical value. The algorithm is available as part of a new multinode well package (MNW2) for MODFLOW.

0 Followers
 · 
94 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Long-screen wells or long open boreholes with intraborehole flow potentially provide pathways for contaminants to move from one location to another in a ground water flow system. Such wells also can perturb a flow field so that the well will not provide water samples that are representative of ground water quality a short distance away from the well. A methodology is presented to accurately and efficiently simulate solute transport in ground water systems that include wells longer than the grid spacing used in a simulation model of the system and hence are connected to multiple nodes of the grid. The methods are implemented in a MODFLOW-compatible solute-transport model and use MODFLOW's Multi-Node Well Package but are generic and can be readily implemented in other solute-transport models. For nonpumping multinode wells (used to simulate open boreholes or observation wells, for example) and for low-rate pumping wells (in which the flow between the well and the ground water system is not unidirectional), a simple routing and local mixing model was developed to calculate nodal concentrations within the borehole. For high-rate pumping multinode wells (either withdrawal or injection, in which flow between the well and the ground water system is in the same direction at all well nodes), complete and instantaneous mixing in the wellbore of all inflows is assumed.
    Ground Water 09/2006; 44(5):648-60. DOI:10.1111/j.1745-6584.2006.00231.x · 1.95 Impact Factor
  • 01/2003: pages 1089; Johnson Screens.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The presence of multiaquifer or multilayer wells changes the nature of the equations which must be solved in a three-dimensional ground-water flow simulation and, in effect, alters the stencil of computation. A method has been devised which takes this change into consideration by allowing simulation of the hydraulic effects of a multiaquifer well on the aquifer system. It also allows for calculation of the water level and individual aquifer discharges in such a well. The method is valid for the case of a single well located at the center of a square node block. Where more than one well per node is involved, the effects of the stencil alteration still must be considered, although difficulties arise in estimating and justifying the parameters to be utilized.
    Ground Water 05/1982; 20(3):334-341. DOI:10.1111/j.1745-6584.1982.tb01354.x · 1.95 Impact Factor

Preview

Download
1 Download
Available from