TEST FOR YIELD OF A WELL
The yield of an open well can be found or tested by the following methods
1. Constant level pumping test
a. Pumping in test
b. Pumping out test
2. Recuperation test.
CONSTANT LEVEL PUMPING TEST
In this test the rate of pumping is so adjusted that water level in the well remains constant. As and when the condition is reached the rate of inflow will be equal to the rate of pumping since it is difficult to maintain constant level in the well this test is generally not adopted to determine the yield.
In the Recuperation test the water from the well is pumped at a faster rate and its level is depressed to certain level is depressed to certain level pumping is then stopped. The time taken for the water to come to its normal level (Recuperate) is recorded.
H1 = initial depression head after pumping stopped (in m)
H2 = depression head in the well at a time(T) after pumping stopped(in m) A = Sectional area of the well (m2)
C = specific capacity of the well in m3/hr/ m2 of the area under in depression head
C= 2.303A/T . log10(H1/H) m3/hr/m(m2 of Area)
Yield of the well Q=CH