Field-Obtained Soil Water Characteristic Curves and Hydraulic Conductivity Functions

Abstract

A compacted clay liner (test pad) was constructed and instrumented with volumetric water content and soil matric potential sensors to determine soil water characteristic curves (SWCC) and hydraulic conductivity (k) functions. Specifically, the compacted clay liner was subjected to an infiltration cycle during a sealed double ring infiltrometer (SDRI) test followed by a drying cycle. After the drying cycle, Shelby tube samples were collected from the compacted clay liner and flexible wall permeability (FWP) tests were conducted on sub-samples to determine the saturated hydraulic conductivity. Moreover, two computer programs (RETC and UNSAT-H) were utilized to model the SWCCs and k-functions of the soil based on obtained measurements including the volumetric water content ( v), the soil matric potential (), and the saturated hudraulic conductivity (k s). Results obtained from the RETC program (θ s , θ r , α, n and k s) were ingested into UNSAT-I would like to express the deepest appreciation to my thesis director, Dr. Richard A. Coffman for giving me the opportunity to conduct this research and guiding me along the way. Without his guidance, mentorship and persistent help this thesis would not have been possible. I would also like to thank my committee members, Dr. Norman D. Dennis and Dr. Michelle Bernhardt for being extraordinary committee members who showed me the road and helped to get me started on the path to this degree. I would also like to thank Cyrus Garner for assisting me to collect and reduce data for the research presented in this document. Also, a special thanks goes out to the students:

Prediction of soil water characteristic curves based on low suction section and inflection point

“…The soil water characteristic curve (SWCC) characterizes the relationship between soil suction and soil water content (saturation, mass water content, volume water content) (Chen et al 2015;Pham et al 2019;Zhao et al 2020a), which is the basis of studying soil water movement and solute transport (Fu et al 2011;Xing et al 2016). Therefore, researchers have developed many methods for the determination of SWCC (Ishimwe et al 2014;Haghverdi et al 2018), among which the centrifugal method is the most widely used. Although the operation is simple, the density change and centrifugal time in the centrifugal process have certain effects on measurement results, so measured parameters often have low accuracy (Sun et al 2019;Wang et al 2019a).…”

Soil-water resistivity curve of a tropical soil

“…It happens because the stabilization time varies according to the level of suction measured and may vary from 7 to 30 days [6][7]. Thus, regarding this delay in obtaining the results, this technique is still under-used and complementary procedures are currently emerging from theoretical and experimental research [8][9][10] to obtain the SWCC in a reduced time.…”

Studying Unimodal, Bimodal, PDI and Bimodal-PDI Variants of Multiple Soil Water Retention Models: I. Direct Model Fit Using the Extended Evaporation and Dewpoint Methods

“…The soil water retention curve (SWRC) is considered the most critical curve in soil physics and has numerous applications in the agro-hydrological areas. A considerable number of studies have been conducted on SWRC's related research topics including in situ and laboratory measurement techniques [1][2][3][4][5], mathematical parametrization [6][7][8][9][10][11][12][13][14][15], and indirect estimation via pedotransfer function (PTF) [1,[16][17][18][19][20][21][22][23]. The SWRC is often used to determine the soil hydraulic conductivity curve via capillary bundle models [24,25].…”