Flow To Wells
The basic, steady state, equation for flow to fully penetrating wells (i.e. wells reaching the impermeable base) in a regularly spaced well field in a uniform unconfined (preactic) aquifer with an hydraulic conductivity that is isotropic is :
where Q = safe well discharge - i.e. the steady state discharge at which no overdraught or groundwater depletion occurs - (m3/day), K = uniform hydraulic conductivity of the soil (m/day), D = depth below soil surface, = depth of the bottom of the well equal to the depth of the impermeable base (m), = depth of the watertable midway between the wells (m), is the depth of the water level inside the well (m), = radius of influence of the well (m) and is the radius of the well (m).
The radius of influence of the wells depends on the pattern of the well field, which may be triangular, square, or rectangular. It can be found as:
where = total surface area of the well field (m2)and N = number of wells in the well field.
The safe well discharge (Q) can also be found from:
where q is the safe yield or drainable surplus of the aquifer (m/day) and is the operation intensity of the wells (hours/24 per day). Thus the basic equation can also be written as:
Read more about this topic: Well Drainage
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