In [1]:
%matplotlib inline
import numpy as np
import matplotlib.pyplot as plt
from ttim import *
Consider a well pumping in a phreatic aquifer with $S_y=0.1$. The hydraulic conductivity of the aquifer is 10 m/d and the saturated thickness may be approximated as constant and equal to 20 m. The well is located at $(x,y)=(0,0)$. The discharge of the well is 1000 m$^3$/d and the radius is 0.3 m. there is a very long river with a fixed head located along the line $x=50$ m. The head is computed at $(x,y)=(20,0)$ for the first 20 days after the well starts pumping. The solution for an image well is compared to the solution using a HeadLineSinkString element of different lengths.
In [2]:
ml1 = ModelMaq(kaq=10, z=[20, 0], Saq=[0.1], phreatictop=True, tmin=0.001, tmax=100)
w1 = Well(ml1, 0, 0, rw=0.3, tsandQ=[(0, 1000)])
w2 = Well(ml1, 100, 0, rw=0.3, tsandQ=[(0, -1000)])
ml1.solve()
t = np.linspace(0.1, 20, 100)
h1 = ml1.head(20, 0, t)
plt.plot(t, h1[0], label='river modeled with image well')
plt.xlabel('time (d)')
plt.ylabel('head (m)');
In [3]:
plt.plot(t, h1[0], label='river modeled with image well')
for ystart in [-50, -100]:
ml2 = ModelMaq(kaq=10, z=[20, 0], Saq=[0.1], phreatictop=True, tmin=0.001, tmax=100)
w = Well(ml2, 0, 0, rw=0.3, tsandQ=[(0, 1000)])
yls = np.arange(ystart, -ystart + 1, 20)
xls = 50 * np.ones(len(yls))
lss = HeadLineSinkString(ml2, xy=list(zip(xls, yls)), tsandh='fixed')
ml2.solve()
h2 = ml2.head(20, 0, t)
plt.plot(t, h2[0], '--', label=f'line-sink string from {ystart} to {-ystart}')
plt.title('head at (x,y)=(20,0)')
plt.xlabel('time (d)')
plt.ylabel('head (m)')
plt.legend();
The solution is repeated for the case where there is a long impermeable wall along $x=50$ m rather than a river.
In [4]:
ml1 = ModelMaq(kaq=10, z=[20, 0], Saq=[0.1], phreatictop=True, tmin=0.001, tmax=100)
w1 = Well(ml1, 0, 0, rw=0.3, tsandQ=[(0, 1000)])
w2 = Well(ml1, 100, 0, rw=0.3, tsandQ=[(0, 1000)])
ml1.solve()
t = np.linspace(0.1, 20, 100)
h1 = ml1.head(20, 0, t)
plt.plot(t, h1[0], label='impermeable wall modeled with image well')
plt.xlabel('time (d)')
plt.ylabel('head (m)');
In [5]:
plt.plot(t, h1[0], label='river modeled with image well')
for ystart in [-100, -200, -400]:
ml2 = ModelMaq(kaq=10, z=[20, 0], Saq=[0.1], phreatictop=True, tmin=0.001, tmax=100)
w = Well(ml2, 0, 0, rw=0.3, tsandQ=[(0, 1000)])
yls = np.arange(ystart, -ystart + 1, 20)
xls = 50 * np.ones(len(yls))
lss = LeakyLineDoubletString(ml2, xy=list(zip(xls, yls)), res='imp')
ml2.solve()
h2 = ml2.head(20, 0, t)
plt.plot(t, h2[0], '--', label=f'line-doublet string from {ystart} to {-ystart}')
plt.title('head at (x,y)=(20,0)')
plt.xlabel('time (d)')
plt.ylabel('head (m)')
plt.legend();