Handbook of Civil Engineering Calculations

FIGURE 2. Relation between groundwater table and ground surface. (Babbitt, Doland and

Cleasby.)

results obtained are most nearly correct when the ratio of drawdown to the depth of water
in the well, when not pumping, is low.
Figure 1 is valuable in analyzing both the main gravity well and its associated bore-
holes. Since gravity wells are, Fig. 2, popular sources of water supply throughout the world,
an ability to analyze their flow is an important design skill. Thus, the effect of the percent-
age of total possible drawdown on the percentage of total possible flow from a well, Fig. 3,
is an important design concept which finds wide use in industry today. Gravity wells are
highly suitable for supplying typical weekly water demands, Fig. 4, of a moderate-size city.
They are also suitable for most industrial plants having modest process-water demand.

Per cent of total possible flow

FIGURE 3. The effect of the percent-

age of total possible drawdown on the

percentage of total possible flow from a

well. (Babbitt, Doland, and Cleasby.)

Per

cent

of

total

possible

drawdown