Aquarius Engineering What's New

What's New

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 support.

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 those numbers.

9/29/2007 - Fitting Head-Discharge Hydraulic Equations to an Experimental Dam Breach Flume Model. (UNDER CONSTRUCTION) 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 deliberate breach.
6/27/2004 - The soil physics tutorial html pages have been replaced by zip files of the original MS PowerPoint presentations for download.
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 solutions.

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.
05/25/2002 - 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 topics.
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 jets.
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 the horizontal and vertical 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 conditions.
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.


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