Soluciones bsicas

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Soluciones básicas
Apuntes preparados por Jesus Carrera con material
de Meier y Poetter
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Ensayo hidráulico
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Interpretación en régimen cuasiestacionario
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Interpretación en régimen cuasiestacionario
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Interpretación con gráfico semilogarítmico
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Acuífero libre con recarga
Derivar la ecuación de nivel en función de Q, K y
w
Despejando K
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Ejercicios
1a Estimate the radius the drawdown cone if the
rate of recharge is 12 inches per year and steady
state conditions have been reached for a well has
been pumped for six months at a rate of 4 gallons
per minute.
1b An unconfined alluvial aquifer with a
hydraulic conductivity of 0.001 cm/s is 20 feet
thick and is pumped at a rate of 9 gallons per
minute. After steady state conditions are
reached, a head of 15 feet above the aquifer base
is measured in an observation well 10 feet from
the pumping well. If the recharge rate due to
precipitation is 12 inches per year, what is the
steady state head in an observation well 20 feet
from the pumping well?
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Ensayos en régimen transitorio

• Beneficios/Desventajas
• Se puede estimar almacenamiento
• Estimación para tiempos cortos
• Fácil de detectar efectos raros
• Análisis mas complejo

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What is drawdown?
h(t) actual heads
hN (t) heads one would observe without pumping
h(t0)
hN(t)
h(t)
t0 Start pumping
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Aproximación de Jacob
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Theis Solution

• Usual assumptions
• Radial Flow
• Infinite aquifer
• Initially constant head
• Horizontal aquifer
• Confined aquifer
• Well of zero radius
• Zero recharge
• Homogeneous T

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Theis Solution

• Discuss after checking concept of drawdown
• NO! (only the added effect of pumping needs to be
  radial
• Yes, but we will see later
• NO!, s(x,y,t) hN(x,y,t) h (x,y,t)
• NO!
• NO!. Only constant T and S
• Yes, but only relevant for early time
• NO!, only needs constant (in time) recharge (OK
  spatial variation)
• Yes, , but still OK for late time

• Usual assumptions
• Radial Flow
• Infinite aquifer
• Initially constant head
• Horizontal aquifer
• Confined aquifer
• Well of zero radius
• Zero recharge
• Homogeneous T

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Solución de Theis
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Función de pozo de Theis
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at the red observation well ..
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An example Pumping well discharges _at_ 500 GPM
from a 100ft thick aquifer Observation well
is 200 ft away Plot as s vs r2/t on same scale
of log paper as W(u) vs u
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Example
W(u)2.15
s1.2ft
r2/t1.95x107ft2/day
u7x10-2
Ejercicio Calcular T, S
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Same example choosing other points
W(u)2.15
s1.2ft
s0.56ft
W(u)1.0
u0.1
r2/t2.8x107ft2/day
r2/t1.95x107ft2/day
u7x10-2
Alternativamente, dibujar s vs. t ajustar con
W(u) vs. 1/u
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For the same example Plot s vs t
to 2.6 x 10-4 day
Dh 1.3 ft
Alternatively Plot S vs log r (for one point in
time) and use Dh drawdown over 1 log cycle r
intercept for zero drawdown to time of plot
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Kruseman y de Ridder example