abstract = "The first goal of this study was determining in-situ
soil's vertical saturated hydraulic conductivity (Ks)
from the measured steady infiltration rate, initial
soil parameters, and test arrangements of the Double
Ring Infiltrometer (DRI) test. This was done by
conducting 30 small scale DRI lab experiment, 9 full
scale in-situ DRI, 9 in-situ Mini-Disk infiltrometer
experiments, several lab measurements, and 864
simulated DRI tests using finite element program
HYDRUS-2D. The effects of the ring diameter, head of
ponding, ring depth, initial effective saturation, and
soil macroscopic capillary length on measured steady
infiltration rates was fully studied. M5' model trees
and genetic programming methods were applied on the
data to establish formulas for predicting the saturated
hydraulic conductivity of the sand to sandy-clay
materials. The accuracy of Ks measurements of each
method was estimated using 30% of 864 data by comparing
the predefined Ks measured from the initial assumptions
of the finite element programs with the estimations of
the suggested formulas. Another comparison was done by
using the derived formulas to predict Ks values of the
9 field DRI experiments and comparing the predicted
values with the Ks values measured with the lab falling
head permeability tests. Compared to genetic
programming method, M5' model had a better performance
in prediction of Ks with correlation coefficient and
the root mean square error values of 0.8618 and 0.2823,
respectively. Tension Disc Infiltrometer was needed
during the first part of the research. This test is a
commonly used test setup for in-situ measurement of the
soil infiltration properties. In the second part of
this study, Mini Disk Infiltrometer was used in the lab
to obtain the cumulative infiltration curve of the
poorly graded sand for various suction rates and the
hydraulic conductivity of the soil material was
measured from the derived information. Various methods
were proposed by several researchers for determination
of hydraulic conductivity from the cumulative
infiltration data derived from Tension Disc
Infiltrometer. In this study, the hydraulic
conductivity measurements were estimated by using eight
different methods. These employed methods produced
different unsaturated and saturated hydraulic
conductivity values. The accuracy of each method was
determined by comparing the estimated hydraulic
conductivity values with the values obtained from the
falling head permeability test.
Finally, as the third part of the research, a system of
automated DRI using Arduino microcontroller, Hall
effect sensor, peristaltic pump, water level sensor,
and constant-level float valve was designed and tested.
The advantages of the current system compared to
previous designed systems was discussed. The system
configuration was illustrated for better understanding
of the set-up. The system was mounted in a portable and
weather resistant box and was applied to run DRI
testing in the field to check the applicability and
accuracy of the portable system in field measurements.
Results of the DRI testing using the automated system
were also presented.",