April 13, 2007
I deeply regret to find that Dr.
H. Don Scott has
passed. He is one of the few men I know who truly deserve
the term "gentleman". He meant a great deal to me at
a very dark time in my life. If he had not given me a place to
work as his Technical Assistant at the University of Arkansas,
I might never have come out of a very deep depression. He put
up with my often bizarre behavior and gave me a reason to get
up in the morning and get on with my life. Where many others
would have tossed me aside, he gave me the space, grace and understanding
I needed to survive. A lot of my published research product owes
him that debt, which I can never repay. I hope it will not do
him any dishonor to dedicate this research and tutorial web site
to his memory. I wrote many of the tutorials here on soil physics,
Richards equation and finite differences, while working for him.
Students from as far away as Indonesia and France still visit
them, and these tutorials would never have existed without his
Don Baker, Ph.D. Soil Physics
Dr. H. Don Scott
Note: This is not
the web site for Ballard's Frame Distributors. The robots
that free directories use to search the net for filler material
aren't very smart.
This is a time-line of what has been added to the
site since September 2000. Due to lack of research support, it
has not been significantly updated since the date at the top.
The Author is currently on disability, and working to become productive
in other areas. As of June 12, 2004, the visits per month were
running from 6,000 to 12,000, including robots and crawlers. Somewhat
less now, but about four to six thousand a month, peaking during
the Northern Hemisphere winter. Removing agents and referrers,
the number of unique sites visiting per month is about 1/4 of
- 9/29/2007 - Fitting Head-Discharge
Hydraulic Equations to an Experimental Dam Breach Flume Model.
Illustrates the use of simulated annealing to fit
equations to the head-discharge data from a trapezoidal weir
model of dam breach. Shows how the areal size of the headcut
(cross-section of flow) compared to the square of upstream overflow
depth can be used in logistic equations to weight the flow between
trapezoidal channel flow to a fully aerated breach jet. One such
fit is good to about 6% in mean relative error, or 0.083 cubic
feet per second (0.00235 cubic meters per second) in mean absolute
error, with a standard deviation of 0.1388 CFS (0.00393 CMS).
- Baker, Donald L., 2006, General Validity of Conductivity
Means in Unsaturated Flow Models, ASCE Journal of Hydrologic
Engineering, Nov/Dec 2006, 11(6):526-538.
- 12/13/2004 - Dam Breach Model
Study. Analysis of a set of plywood flume
models simulating dam breach. Equations developed for no head
cut, and for head cut with aerated jet into a head cut. Determined
that there was not enough data to fully define the equation for
the transformation between those forms.
- 10/2/2004 - Monitoring
of an Engineered Dam Breach. Piezometers set up to monitor
the apparent phreatic surface during earthen dam wet-up and a
- 6/27/2004 - The soil physics tutorial html pages have been
replaced by zip files of the original MS PowerPoint presentations
- 6/17/2004 - Infiltration
into Poultry Litter, Program and Manual. This
is old work (circa September 2000 to February 2001) that was
previously on the research web site of Dr. H. Don Scott when
he was at the University of Arkansas, Fayetteville. It disappeared
from that server when he became Director of the Agribusiness
Center of Mount Olive College, NC. It contains the soil and weather
data of a poultry waste infiltration experiment in six plots
of tall fescue, replicated twice on each plot, for the growing
seasons of 1990 and 1991. It has several draft papers on modeling
infiltration and nitrogen transport in a soil column, the Fortran
program that was partially developed for this, and a description
of its attempted calibration for infiltration. Although it was
not calibrated as such, it contains program code to account for
degradation of the animal waste on the soil surface, dumping
of the chemical products to the soil with rain, and the influence
of plant uptake and evapotranspiration. This program may have
errors, and should be verified before use.
- 1/30/2003 - The
ultimate adaptive grid? The "exact" solutions for
Richards' equation developed in 2000/2001 have uniform grids
in saturation (left) as opposed to uniform in space (right) as
in the finite difference solution. This means that for every
time and infiltration depth the grid points of the "exact"
solution will stick with the wetting front, no matter how sharp
it is. This makes it a viable independent solution for testing
the effects of adaptive gridding schemes in finite difference
- 10/12/2002 - Principle Investigator looking for work
- Click here for vita.
In September, 2001, the State of Oklahoma certified me as a person
with a severe disability. I am not willing to work with hazardous
materials, and am unable to do grunt work in the field. I have
some difficulty walking, but can still work 1/2 time. I'm looking
for a research or technical position in any appropriate field,
with health benefits and a take-home pay of $1500.00/month or
more. My geographic preference is anywhere in the U.S., excluding
Hawaii, California, and the New England states from Maryland
to Massachusetts. My background is primarily in electronics engineering
(a bit dated) and numerical methods for ground water modeling.
I have set up a number dataloggers in the field and even designed
a couple. In related fields such as surface water hydrology,
I am willing to start well below my degrees, within reason, in
order to gain the necessary experience, knowledge, skills and
abilities. I have a few research proposals pending. If the major
proposal is funded in January 2003 while I am employed (a one
in ten chance), I may leave for it or asked to be assigned to
work on it, if appropriate.
- Someone correctly pointed out that the PowerPoint
sources in the Soil Physics Tutorials will not download with
all the images. This may not be fixed for some time.
- 05/01/2002 - Soil
Physics Tutorials; a short course in soil physics, 585 PowerPoint
slides in html, with ppt source files, undergraduate to postdoctorate
- 05/01/2002 - Draft paper: A Quasi-Analytic Exact Solution of Richards
Equation for Vertical Unsaturated Flow in Homogeneous Media with
Variable Inflow, the last in a set that compares a numerical
model with Darcian means and 2nd-order DIRK time steps to the
new exact solution.
- 02/23/2002 - Some
notes on the application of the Buckingham Pi theorem to a dam
breach model. How do you do math?
- 02/23/2002 - A
dam breach discharge study. Work done with data from a set
of physical scale models of dam breach. Includes calibrated head-discharge
equations for a dam breach model with aerated and fully supported
jets, with work indication a possible solution to partially-supported
- 02/23/2002 - Pressure/Tensiometer Sensors in an Engineered
Dam Failure. The development and use of pressure/tensiometer
sensors to track the development of the phreatic surface in a
test embankment as it is wetting and then destroyed. Revised
from presentation of November 14, 2001. (Removed from site)
- 01/18/2001 - Draft
papers: Exact numerical solutions to Richards' equation in
cases for fixed-flux inflow boundary conditions. At
least in these cases, it turns out, diffusivity does not have
to decrease in magnitude with saturation. This demonstrates,
among other things that Darcian means work with flow boundary
- 12/29/2000 - Draft papers: Exact numerical solutions
to Richards' equation in horizontal and vertical cases of fixed-head inflow boundary
condition. Richards' equation is transformed
into a second-order differential equation of fraction flow with
respect to relative saturation. Unlike many current approaches,
this one requires only that diffusivity and conductivity be expressible
as continuous functions of saturation in a Fortran subroutine,
where both decrease with decreasing saturation. The use of easily-understood
physical concepts in the mathematical transformations make this
a good tutorial. Work on flow boundary conditions to come later.
- 09/16/2000 - Poultry
Litter Notebook; A new area was being assembled on Dr. H.
Don Scott's web page which had notes on modeling the infiltration
of nutrients from surface-applied poultry litter. It disappeared
when Dr. Scott became the Director of the Agribusiness Center
at Mount Olive Colleg, NC. It is reproduced here (June 2004)
so that the data and material will not be lost to other researchers.
- Legal notice: Although the information in this site
was created in good faith, use it at your own risk.
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