TM 5-815-5/AFM 88-5, Chap 6/NAVFAC P-418
U.S. Army Corps of Engineers
Figure 4-8. Flow and drawdown at slot for fully and partially penetrating rectangular slots; circular source; artesian flow.
ures 4-1 through 4-22 do not consider hydraulic head
quate "wetted screen length hws" or submergence to
pass the maximum computed flow. The limiting flow
losses that occur in the filter, screen, collector pipes,
qc into a filter or well screen is approximately equal to
etc. These losses cannot be neglected, however, and
7.48 gallons per minute
must be accounted for separately. The hydraulic head
x per foot of filter
loss through a filter and screen will depend upon the
diameter of the screen, slot width, and opening per
foot of screen, permeability and thickness of the filter;
any clogging of the filter or screen by incrustation,
rW = radius of filter or screen
drilling fluid, or bacteria; migration of soil or sand par-
k = coefficient of permeability of filter or aquifer
ticles into the filter; and rate of flow per foot of screen.
sand, feet per minute
Graphs for estimating hydraulic head losses in pipes,
wells, and screens are shown in figures 4-24 and 4-25.
(5) Hydraulic head loss Hw. The equations in fig-