Hi! Good information here. But aren't you missing the lambda exponent on the relative saturation term in the hydraulic conductivity function? I have literature that shows a lambda exponent on there, but its missing here, so just confused. Thanks in advance.
Hello. Thanks for the excellent video. I have a question about finding Hp of a soil from the curve. Could you please help me with this: I have a soil with theta_s=0.32, theta_r=0.01, the soil field moisture content is 35.2%. I have the retention curve, but I don't know how to extract its related Hp from the curve. Do I need to use the field moisture content as theta in the bottom axis to find the Hp on the vertical axis? If yes, field moisture content=35.2% is more than theta_s=0.32. Is this possible?
@@selkerjss Yes, thank you so much for clarification, that's exactly why I asked it. I actually got these data from a lab, there is a column of data called "saturation" which I think it's the saturated system to start pulling the water out. I've asked them to clarify it, and if it's the case, then theta_s would be more than field moisture content that seems to be right. Just another quick question: Is the field moisture content (%) at 105 degree, the gravimetric moisture content? If yes, I will need to convert it to volumetric moisture content, put this on the curve and get the related pressure (h), right? Thanks again!
@@nasrintaghavi6877 Hello Nasrin - when you see data associated with 105 degrees, this is typically indicating the "oven dry" condition. It can be expressed either gravimetrically or volumetrically, which in either case can be put in % terms. So I cannot give you a solid answer. You need to look at the laboratory procedures.
van Genuchten, M.Th. (1980). "A closed-form equation for predicting the hydraulic conductivity of unsaturated soils". Soil Science Society of America Journal. 44 (5): 892-898. Bibcode:1980SSASJ..44..892V. doi:10.2136/sssaj1980.03615995004400050002x. hdl:10338.dmlcz/141699.
Look up the "instantaneous profile method." Typically you use a TDR/dielectric sensor or neutron probe for moisture, and a tensiometer for pressure. You dig a hole, and install them into the sides of the hole and re-fill the hole. That said, there are many approaches - it really depends on your site and objectives.
@@selkerjss I understood John. My focus of my question is this. I´m a Metallurgical Engineering, and I need to model the movement of solution in a unsaturated porous media (heap leaching), but the studies that I have been read they modelling the head of suction vs saturation or moisture of ore using the Van Genuchten model. But how they measurement both parameters (head of suction and saturation) to adjust the permeability? Can you ligth me in that please. Greetings Jaime
You are just awesome... I love all your soil lectures.
you help me understand this confusing thing, Thanks for sharing sir!
Excellent, thank you so much!!!
Hi! Good information here. But aren't you missing the lambda exponent on the relative saturation term in the hydraulic conductivity function? I have literature that shows a lambda exponent on there, but its missing here, so just confused. Thanks in advance.
i think l (nomally 0.5) is missing there?
As one of the comments mentioned below, l is missing in the relative hydraulic conductivity equation I think.
In what year U.S. net farm income swelled to $33.3 billion?
could you send me the simulation control with simulink-matlab of the richards equation?
Hello. Thanks for the excellent video. I have a question about finding Hp of a soil from the curve. Could you please help me with this: I have a soil with theta_s=0.32, theta_r=0.01, the soil field moisture content is 35.2%. I have the retention curve, but I don't know how to extract its related Hp from the curve. Do I need to use the field moisture content as theta in the bottom axis to find the Hp on the vertical axis? If yes, field moisture content=35.2% is more than theta_s=0.32. Is this possible?
Please note that in this formulation, theta-s is the maximum water content of a soil. So your proposed situation is not possible.
@@selkerjss Yes, thank you so much for clarification, that's exactly why I asked it. I actually got these data from a lab, there is a column of data called "saturation" which I think it's the saturated system to start pulling the water out. I've asked them to clarify it, and if it's the case, then theta_s would be more than field moisture content that seems to be right. Just another quick question: Is the field moisture content (%) at 105 degree, the gravimetric moisture content? If yes, I will need to convert it to volumetric moisture content, put this on the curve and get the related pressure (h), right?
Thanks again!
@@nasrintaghavi6877 Hello Nasrin - when you see data associated with 105 degrees, this is typically indicating the "oven dry" condition. It can be expressed either gravimetrically or volumetrically, which in either case can be put in % terms. So I cannot give you a solid answer. You need to look at the laboratory procedures.
@@selkerjss Dear John, thanks for your help!
It is not mentioned in the laboratory files, so I just asked them to clarify it.
Cheers.
Please can you share soil hydrology and biophysics
what is the reference for this?
van Genuchten, M.Th. (1980). "A closed-form equation for predicting the hydraulic conductivity of unsaturated soils". Soil Science Society of America Journal. 44 (5): 892-898. Bibcode:1980SSASJ..44..892V. doi:10.2136/sssaj1980.03615995004400050002x. hdl:10338.dmlcz/141699.
thanks dude
How we can measure the values of pressure and saturation of a soil in different deep. I would like to write to your email.
Look up the "instantaneous profile method." Typically you use a TDR/dielectric sensor or neutron probe for moisture, and a tensiometer for pressure. You dig a hole, and install them into the sides of the hole and re-fill the hole. That said, there are many approaches - it really depends on your site and objectives.
@@selkerjss I understood John.
My focus of my question is this. I´m a Metallurgical Engineering, and I need to model the movement of solution in a unsaturated porous media (heap leaching), but the studies that I have been read they modelling the head of suction vs saturation or moisture of ore using the Van Genuchten model. But how they measurement both parameters (head of suction and saturation) to adjust the permeability? Can you ligth me in that please. Greetings Jaime
Thank you
Hello, any one can help me by giving Modflow and Hydrus software for Macbook, thanks
Well Explain You great concepts are clear now