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What is the radius of influence of the pumping well?
Radius of Influence means the radial distance from the center of a well bore to the point where there is no lowering of the water table or potentiometric surface because of pumping of the well; the edge of the cone of depression.
How do you find the radius of influence in an unconfined aquifer?
R=√{1.9 Ksat h t / n}, for unconfined aquifers (Aravin and Numerov, 1953) “sichardt”: R=3000 s √{Ksat}, Sichardt formula for unconfined aquifers (Cashman and Preene, 2001)
What is Sichardt equation?
DUPUIT-THIEM EQUATION (unconfined aquifer, steady state conditions) Empirical Formula of Sichardt. Q=piK(Ho^2-hw^2)/2.3log(R0/re) R0=C(h0 – h)SQRT(K)
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 .
How do you find the radius of influence?
Solution to drawdown problem Radius of influence (R) for a well may be calculated using the following equation: R = b*(SQRT(K/(2*N))), where b is the thickness (100m), K is hydraulic conductivity (1e-5 m/sec), and N is the recharge (0.75 m/yr or 2.378e-8 m/sec).
When would the dam become irrelevant?
When would the dam become irrelevant? Explanation: A dam is built across a river primarily to store water in the form of a reservoir. The whole idea of a dam would become irrelevant if the foundations on which it is built are made of porous rocks or if a stretch of a reservoir rock is permeable.
What influences the shape of the cone of depression?
The size and shape (slope) of the cone of depression depends on many factors. The pumping rate in the well will affect the size of the cone. Also, the type of aquifer material, such as whether the aquifer is sand, silt, fractured rocks, karst, etc., also will affect how far the cone extends.
How do you calculate dewatering volume?
In order to construct the building, dewatering has to be done by laying pumps at various junctions. Calculate the rate of flow of water when one pump is laid and compare it with the discharge when the number of pumps is increased. = 2m and k = 10-3 m/s, the yield for a single well is obtained as 0.01 m3/s.
What is a well function?
A well is an excavation or structure created in the ground by digging, driving, or drilling to access liquid resources, usually water. The oldest and most common kind of well is a water well, to access groundwater in underground aquifers.
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 is confined aquifer?
Confined aquifers are permeable rock units that are usually deeper under the ground than unconfined aquifers. Groundwater in a confined aquifer is under pressure and will rise up inside a borehole drilled into the aquifer. The level to which the water rises is called the potentiometric surface.
What is unit hydrograph helpful?
Explanation: Unit hydrograph is helpful in estimating runoff from a basin for a storm of given duration. It is also helpful in predicting the expected flood flow from a catchment if rainfall intensity in the catchment is known.