Users' questions

What is Theis curve?

What is Theis curve?

The Theis equation (Theis, 1935) describes radial confined groundwater flow in a uniformly thick horizontal, homogeneous, isotropic aquifer of infinite areal extent. S = (Q / 4πT) ∫(r2s/4Tt)∞ [(e-u/u) du] (1) The radius of the pumped well is assumed negligible (line source or sink approximation).

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.

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 the Thiem 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.

Is curve represent?

The IS curve depicts the set of all levels of interest rates and output (GDP) at which total investment (I) equals total saving (S). The LM curve depicts the set of all levels of income (GDP) and interest rates at which money supply equals money (liquidity) demand.

How is transmissivity calculated?

the hydraulic conductivity is therefore measured in area of water per unit time. Define transmissivity mathematically. We have T = KhD where T is the transmissivity, Kh is the average horizontal conductivity and D is the aquifer thickness.

What are the assumptions for the confined aquifer test?

Within a confined aquifer, the following assumptions are made to establish the Thiem equilibrium point. It is always assumed that the geological formation is homogeneous, isotropic and infinite, and areal extended.

Is clay an Aquitard?

Clay usually acts as an aquitard, impeding the flow of water. Gravel and sand are both porous and permeable, making them good aquifer materials.

IS curve shows the relationship between?

The IS curve shows the relationship between interest rates generated in financial markets and the equilibrium level of income the economy gravitates toward given these rates.

IS curve a variable?

The IS curve shows the causation from interest rates to planned investment to national income and output. For the investment–saving curve, the independent variable is the interest rate and the dependent variable is the level of income.

Which aquifer has highest transmissivity?

The Simsboro Formation and Carrizo Sand portions of the Carrizo- Wilcox aquifer have transmissivity and hydraulic-conductivity values that are 2.5 to 11 times higher and 2 to 6 times higher, respectively, than that of the Cypress aquifer, Calvert Bluff Formation, and undivided Wilcox Group.

How is Theis method used in hydrology?

Out of these, Theis method involves curve matching. The oth er two are approximate methods. 1.3 Theis method Theis method is one of the widely applied methods in groundwat er hydrology to determine S and T1, 2. However, this method requires curve matching of a ty pe-curve and time- drawdown data from a pumping well test.

How to calculate Theis method of estimating?

Ì 8\Í\ç Eq. 3(c) where s is drawdown in the pumping well, Q is constant well discharge, and W(u) is well function. Theis nonequilibrium equation allows determining the stor age coefficient( S) , and the transmissivity ( T) of the aquifer.

What does Pi stand for in surveying curves?

Point of Intersection (PI) The point of intersection marks the point where the back and forward tangents intersect. The surveyor indicates it as one of the stations on the preliminary traverse.

How to calculate the data for a curve?

Curve data are then calculated as: R = 5729.578 D L = 0.0174533 R ∆ Ε = R cos ∆ 2 – R T = R tan ∆ 2 PC = PI – T PT = PC + L FOR 373 Fall Semester 5 Choosing D when the tangent distance is limited. The tangent distance must often be limited in setting a curve. Examples are stream crossings, bluffs, and reverse curves.