chapter 4: temperature inside the landfill

∂θ
∂K(
θ ) ∂ ⎡ ∂θ
⎤
− −
⎢
D(
θ )
⎥
= 0
∂t
∂t
∂Z
⎣ ∂Z
⎦
Neglecting the third term in the above equation, the resulting equation describes
unsaturated flow in the landfills:
∂θ
∂K
( θ )
− = 0
∂t
∂t
From equation 2-6 it can be shown that hydraulic conductivity decreases with decreasing
moisture content and ultimately reaches zero at field capacity. On the other hand, hydraulic
conductivity increases rapidly as moisture content reaches saturation and becomes constant when
it is at maximum.
Straub and Lynch (1982) used power law equations to model unsaturated characteristics
of porous media.
h =
hs
⎡ θ ⎤
⎢ ⎥
⎣θ
s ⎦
−b
Where h is the suction head, hs is the saturation suction head, θ is the volumetric moisture
content, θs is the Saturation moisture content, and b is the suction head fitting parameter.
Equation 2-8 is the another equation proposed by Straub and Lynch (1982).
⎡ θ ⎤
K = K s ⎢ ⎥
⎣θ
s ⎦
B
9
(2-5)
(2-6)
(2-7)
(2-8)