Reference no: EM133111079
Question 1:
A. Write an expression for the water potential in an unsaturated and a saturated soil.
B. Explain what total water potential measures.
C. Explain what each of the individual water potentials measure. Include: how are the pressure and matric potentials different, and how are they similar?
D. You will see water potentials expressed in units of energy, pressure and length. How can these units be interchanged in this way?
Question 2:
The pores in a block of pumice stone are 1 mm in diameter (assume you can treat all pores as having the same diameter, an unrealistic but simplifying assumption), and the stone has porosity 0.7 and measures 8 x 11 x 5 cm (W x L x H). In this question you will estimate the volume of water the stone can take up through capillary effects.
The problem set up (on a "per pore" basis) is involves the formation of a meniscus via capillary action (see figure). There is a pressure difference across the curved interface. This is balanced by the hydrostatic pressure in the fluid at the bottom of the pore. To solve the problem, take the surface tension of water as 72 x 10-3 N/m. Assume that the contact angle (the angle between the surface of the water and the edge of each pore) is 00 (the curvature is semi-spherical).
A. Assume that the stone sits in a tray of water that contains free water to a depth of 1 mm. Determine the average height of water (relative to the tray) in each pore.
B. What is the total volume of water in the stone?
Question 3: For a sandy loam soil, calculate the infiltration rate (cm/hr) and depth of infiltration (cm) after one hour, if the effective saturation (i.e., the relative soil moisture) initially is 40%. Assume continuous ponding. For the sandy loam soil, assume that the effective porosity θ = 0.412, hmf = 11.01 cm, and the hydraulic conductivity Ks = 1.09 cm/hr.
Question 4: Compute the ponding time and cumulative infiltration at ponding for a clay loam soil ( θ = 0.309, hmf = 20.88 cm, Ks = 0.1 cm/hr) with 25% initial effective saturation (i.e., relative soil moisture), subject to rainfall intensity of (a) 1 cm/hr, and (b) 3 cm/hr.
Attachment:- Ponding time and cumulative infiltration.rar