What is Thiem equation?

What is Thiem equation? As with any analytical model, the Thiem equation simplifies the actual geometry and boundary conditions, and assumes steady-state flow in a fully confined, horizontal and homogeneous aquifer (Fig. 1). What is

As with any analytical model, the Thiem equation simplifies the actual geometry and boundary conditions, and assumes steady-state flow in a fully confined, horizontal and homogeneous aquifer (Fig. 1).

What is theis method?

The Theis (1935) solution is useful for determining the transmissivity of nonleaky confined aquifers from recovery tests. Analysis involves matching a straight line to residual drawdown data collected after the termination of a pumping test.

How do you solve the equation of Theis?

Theis Equation

T = aquifer transmissivity [gpd/ft]
S = aquifer storativity.
Q = discharge or well-pumping rate [gpm]

What are the assumptions in the Theis equation?

This implementation is based on the text “Hydraulics of Groundwater” by Jacob Bear (2007) and makes the following assumptions: the aquifer is infinite, confined, homogeneous, and isotropic; the aquifer is horizontal and groundwater flow is horizontal; and. the well diameter is negligible.

What is Dupuit equation?

The Dupuit-Thiem equation is normally used to assess flow towards a pumping well in unconfined aquifers under steady-state conditions. For the formulation of the equation it is assumed that flow is laminar, radial and horizontal towards the well.

How is transmissivity calculated?

Transmissivity is equal to the product of the aquifer thickness (m) and hydraulic conductivity (K) and it is described in units of gpd/ft (gallons per day per foot of aquifer thickness). One method to estimate storativity for confined aquifers is to multiply the aquifer thickness by 0.000001.

What is U in theis equation?

Numerical Approximation. W(u) is the exponential integral and is tabulated in many places (Abramowitz and Stegun, 1968). For specific values of u, table interpolation may be used to obtain the drawdown.

What is a Theis curve?

A log-log plot of the well function, W(u), versus the argument u, in which u describes for a confined aquifer the theoretical relationships among observation-well distance, time since pumping began, and the aquifer storativity coefficient and transmissivity .

What are the three recovery analysis methods?

Three methods available for estimating aquifer properties from recovery test data include the following:

residual drawdown analysis (s’ versus log t/t’)
Agarwal method (recovery versus Agarwal equivalent time)
combined analysis of drawdown and recovery data (s versus t)

What does Darcy’s law state?

A law in geology describing the rate at which a fluid flows through a permeable medium. Darcy’s law states that this rate is directly proportional to the drop in vertical elevation between two places in the medium and indirectly proportional to the distance between them.

What is K in Darcy’s law?

K is the hydraulic conductivity [L/T] the law is very similar to Ohm’s law for electrical curcuits I = 1/R * U (current = voltage divided by resistance) the orginal Darcy experiment yielded these data (Fig 6.4)

What is the unit of transmissivity?

transmissivity (T) The rate at which groundwater is transmitted through a unit width of an aquifer under a unit hydraulic gradient. It is often expressed as the product of the hydraulic conductivity and the full saturated thickness of the aquifer and has units of the form m 3/day/m.

How are theis equations based on the aquifer?

The Theis equations are based on the assumption that the water is released from storage in the aquifer in immediate response to the decline in the water table. In unconfined aquifers, gravity drainage may not be immediate, particularly in fine grained formations and with stratifications of slow yielding materials.

How is the yield of an unconfined aquifer determined?

Thus, for an unconfined aquifer with delayed yield, a pumping test should be continued sufficiently long to obtain the third segment of the curve and S (= S y) can be determined by one of the methods of solution of the non-equilibrium equation.

Which is Theis nonequilibrium method for unconfined aquifers?

AQTESOLVprovides visualand automaticmethods for matching the Theis nonequilibrium method for unconfined aquifers to data from pumping testsand recovery tests. The estimated aquifer properties are as follows: T(transmissivity) S(storativity)