hunt: Streamflow depletion in partially penetrating stream with...

Description Usage Arguments Details Value References Examples

View source: R/hunt.R

Description

Streamflow depletion in partially penetrating stream with semipervious streambed.

Usage

1
hunt(t, d, S, Tr, lmda, lmda_max = Inf, 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)

Tr

aquifer transmissivity [L2/T]

lmda

streambed conductance term, lambda [L/T]. Can be estimated with streambed_conductance.

lmda_max

maximum allowed 'lmda' [L/T]. If 'lmda' is too high, exp and erfc calculations in Hunt solution are not computationally possible, so you may need to artifically reduce 'lmda' using this term.

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.

Details

This function is described in Hunt (1999). When lmda term gets very large, this is equivalent to glover. It contains numerous assumptions:

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

Hunt, B (1999). Unsteady Stream Depletion from Ground Water Pumping. Ground Water 37 (1): 98-102. doi:10.1111/j.1745-6584.1999.tb00962.x.

Examples

1
2
3
4
5
6
7
8
hunt(t = 1826, d = 1000, S = 0.2, Tr = 8640, lmda = 864)    # ~equal to glover because lmda=Tr
hunt(t = 1826, d = 1000, S = 0.2, Tr = 8640, lmda = 0.864)  # less depletion due to lower lmda

lmda <- streambed_conductance(w = 10, Kriv = 0.0864, briv = 1) # estimate lmda
hunt(t = 1826, d = 1000, S = 0.2, Tr = 8640, lmda = lmda)

Qf <- hunt(t = seq(1, 1826), d = 1000, S = 0.2, Tr = 8640, lmda = 0.864)
plot(x = seq(1, 1826), y = Qf, type = "l")

streamDepletr documentation built on March 26, 2020, 7:27 p.m.