On the predictability of the water-table variation in a ditch-drainage system |
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Authors: | Shivendra Nath Rai Rishi Narain Singh |
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Affiliation: | (1) National Geophysical Research Institute, 500007 Hyderabad, India |
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Abstract: | The irrigation in regions of brackish groundwater in many parts of the world results in the rise of the water-table very close to the groundsurface. The salinity of the productive soils is therefore increased. A proper layout of the ditch-drainage system and the prediction of the spatio-temporal variation of the water table under such conditions are of crucial importance in order to control the undesirable growth of the water-table. In this paper, an approximate solution of the nonlinear Boussinesq equation has been derived to describe the water-table variations in a ditch-drainage system with a random initial condition and transient recharge. The applications of the solution is discussed with the help of a synthetic example.Notations
a
lower value of the random variable representing the initial water-table height at the groundwater divide
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a+b
upper value of the random variable representing the initial water-table height at the groundwater divide
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h
variable water-table height measured from the base of the aquifer
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K
hydraulic conductivity
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L
half width between ditches
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m
0
initial water-table height at the groundwater divide
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N(t)
rate of transient recharge at time t
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N
0
initial rate of transient recharge
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P
N
0/K
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S
Specific yield
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t
time of observation
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t
0
logarithmic decrement of the recharge function
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T
Kt/SL
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x
distance measured from the ditch boundary
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X
x/L
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Y
h/L
- Y
mean of Y
- Y
Variance of Y |
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Keywords: | Water table ditch-drainage nonlinear Boussinesq equation random initial condition transient recharge |
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