hunt | R Documentation |
Streamflow depletion in partially penetrating stream with semipervious streambed.
hunt(t, d, S, Tr, lmda, lmda_max = Inf, prec = 80)
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 |
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 |
This function is described in Hunt (1999). When lmda
term gets very large, 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
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
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.
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")
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