hantush {streamDepletr}

Streamflow depletion in partially penetrating stream with semipervious streambed.

Description

Streamflow depletion in partially penetrating stream with semipervious streambed.

Usage

hantush(t, d, S, Kh, b, Kriv, briv, prec = 80)

Arguments

t

times you want output for [T]

d

distance from well to stream [L]

S

aquifer storage coefficient (specific yield if unconfined; storativity if confined)

Kh

aquifer horizontal hydraulic conductivity [L/T]

b

aquifer saturated thickness [L]

Kriv

streambed semipervious layer hydraulic conductivity [L/T]

briv

streambed semipervious layer thickness [L]

prec

precision for Rmpfr package for storing huge numbers; 80 seems to generally work but tweak this if you get weird results. Reducing this value will reduce accuracy but speed up computation time. If set to 'NULL', the 'mpfr' function is not used which can address an occasional issue on Mac computers but lead to problems under some combinations of 'Tr' and 'lmda'.

Details

This function is described in Hantush (1965). As the leakance term (b*Kh/Kriv) approaches 0 this is equivalent to glover. It contains numerous assumptions:

• Horizontal flow >> vertical flow (Dupuit assumptions hold)

• Homogeneous, isotropic aquifer

• Constant Tr: Aquifer is confined, or if unconfined change in head is small relative to aquifer thickness

• Stream is straight, infinitely long, and remains in hydraulic connection to aquifer

• Constant stream stage

• No changes in recharge due to pumping

• No streambank storage

• Constant pumping rate

• Aquifer extends to infinity

Value

A numeric of Qf, streamflow depletion as fraction of pumping rate [-]. If the pumping rate of the well (Qw; [L3/T]) is known, you can calculate volumetric streamflow depletion [L3/T] as Qf*Qw

References

Hantush, MS (1965). Wells near Streams with Semipervious Beds. Journal of Geophysical Research 70(12): 2829-38. doi:10.1029/JZ070i012p02829.

Examples

hantush(t = 1826, d = 1000, S = 0.2, Kh = 86.4, b = 100, Kriv = 0.0864, briv = 1)

Qf <- hantush(t = seq(1, 1826), d = 1000, S = 0.2, Kh = 86.4, b = 100, Kriv = 0.0864, briv = 1)
plot(x = seq(1, 1826), y = Qf, type = "l")