Groundwater and Well Hydraulics
Well in a Uniform Flow
A practical situation is that of a well pumping from an aquifer having a uniform flow field, as indicated by a uniformly sloping piezometric surface or water table. It is apparent that the circular area of influence associated with a radial flow pattern becomes distorted; however, for most relatively flat natural slopes the Dupuit radial flow equation can be applied without appreciable error.
For wells pumping on an area with a sloping hydraulic gradient, the hydraulic conductivity can be determined from the equation by inserting average heads and hydraulic gradients. The resulting expression has the form-
K = 2Q / [r (hu + hd) (iu + id)]
For an unconfined aquifer where Q is the pumping rate, hu and hd are the saturated thickness, and id and iu are the water table slopes at distance r upstream and downstream, respectively, from the well. For a confined aquifer, piezometric slopes replace water table slopes, and (hu + hd) is replaced by 2b where b is the aquifer thickness.
The groundwater divide marking the boundary of the region producing inflow to the well is shown. For a well pumping for an infinite time, the boundary would extend up to the limit of the aquifer. The expression for the boundary of the region producing inflow can be derived by superposition of radial and one-dimensional flow fields to yield
-y/x = tan(Kbiy/Q)
Where b is the aquifer thickness Q is the discharge rate, i is the natural piezometric slope, and K is hydraulic conductivity. The boundary asymptotically approaches the finite limits
yL = (Q/2Kbi)
as x= ∞. The boundary of the contributing area extends downstream to a stagnation point where,
xL = (Q/2Kbi)
It follows that the upstream inflow zone equals 2xL.
An important practical application of these equations concerns determining whether an upstream pollution source will affect a nearby pumping well.
A fully penetrating production well with a radius of 0.5 m pumps at the rate of 15L/s from a 35-m thick confined aquifer with a hydraulic conductivity of 20 m/d. If the distance and the observed piezometric head drop between two observation wells were 1000m and 3m, respectively, before the production well was installed, determine the longitudinal and transverse limits of groundwater entering the well.
First determine the slope of the piezometric surface under natural conditions (i.e. before the production well was installed):
i = Δh/Δx = 3/1000 = 0.003
You May Also Like-
Groundwater and Well Hydraulics: Steady Unidirectional Flow
Are you on A risk? Read About Risk Assessment.
Have you done the Risk Assessment? Lets’s do Risk Analysis.
Threats to Information System
Software/Security Threats
What do you mean by Information Security?
Shrinkage In Concrete: Types and Methods to Reduce
Chemical Shrinkage
Autogenous Shrinkage
Plastic Shrinkage
Drying Shrinkage
Carbonation Shrinkage
Continue Reading Shrinkage In Concrete: Types and Methods to Reduce
Soil: Definition and Names of Various Types of Soil
The term ‘soil’ in soil engineering is defined as an unconsolidated material, composed of solid particles, produced by the disintegration of rocks. The void space between the particles may contain air, water or both. The soil particles may contain organic matter.
Continue Reading Soil: Definition and Names of Various Types of Soil
Bricks: Uses, Size, Weight, Frog, Types, and Much More
What are Bricks? Bricks are one of the oldest building materials and it’s extensively used at present as a loading material in construction methods because of its durability, strength, reliability, low cost, easy availability, etc. Bricks are manufactured by molding burnt clay or a mixture of sand and lime or of Portland cement concrete, in…
Continue Reading Bricks: Uses, Size, Weight, Frog, Types, and Much More
Water Proofing Materials, Damp-Proofing Course, and much more
Water Proofing Materials Dampness in a building is the main cause of the deterioration of the building as well as for the ill-health of the occupants. The damp brickwork in the buildings is prone to fresh attack. Also, the soluble salts in bricks are liable to attack the cement mortar when the brickwork remains wet…
Continue Reading Water Proofing Materials, Damp-Proofing Course, and much more
Sound Insulation And Sound Insulating Materials
Sound Insulation A well-designed building should incorporate sound insulation to restrain the noise level. High noise conditions result in uncomfortable living conditions, mental strains, fatigue, and may even lead to a nervous breakdown or temporary deafness. Adequate insulation can be achieved by using sound-absorbing or sound repellent materials. Sound Insulating Materials Sound Insulating Materials fall…
Continue Reading Sound Insulation And Sound Insulating Materials
Heat Insulating Materials: Convection, Radiation, and Conduction
Heat Insulating Materials The purpose of thermal insulation is to restrict the heat transfer from warmer to cooler areas. Transfer of heat takes place by three processes- the convection, the radiation and, the conduction. Convection In convection, heat is transferred from one place to another by the movement and mixing of liquids or gases. Radiation…
Continue Reading Heat Insulating Materials: Convection, Radiation, and Conduction
Leave a Reply