Saurav Sinha

ORCID Identifier(s)

0000-0001-5101-7521

Graduation Semester and Year

2016

Language

English

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering

Department

Civil Engineering

First Advisor

Xinbao Yu

Abstract

The study of water flow or infiltration in an unsaturated soil is a highly non-linear and complex problem, simultaneous verification of field and laboratory results is a convenient and practical approach to test the results. In this study, Time domain reflectometry (TDR) sensors are installed at three different locations close to a water body (Creek) in Arlington, Texas which is a part of the National Science Foundation Project titled “Cyper SEES: Type 2: Integrative Sensing and Prediction of Urban Water for Sustainable Cities (iSPUW)”. Time Domain Reflectometry (TDR) and Time Domain Transmissometry (TDT) sensors were deployed at five different depths i.e. 5 cm, 10 cm, 25 cm, 50 cm and 100 cm from the ground level. The infiltration process or the water movement through the soil was studied taking into consideration the soil moisture characteristics (moisture content, field capacity and permanent wilting point). Other soil parameters such as porosity, liquid limit and in-situ density were taken into account for having a better judgement of the soil. A turf-tech Infiltrometer was also employed at the three site locations for the measurement of the infiltration rate and saturated hydraulic conductivity of the soil. To understand the concepts of the infiltration in the soil through laboratory experiments, a single 3 probe TDR sensor soil model was developed and tested with ASTM Graded Sand. Further improvement was made to design a 1 meter long soil column model. In this laboratory study, the details of the soil column apparatus, the procedures adopted for constructing the soil column, and the performance of the apparatus are presented. The major instruments for the soil column apparatus consisted of time domain reflectometry (Strip and Probe), Data acquisition system, and Electronic Weighing Balance. By using these instruments, the vertical infiltration in the soil was studied w.r.t the ASTM Graded Sand. From the field results, it was found that light rainfall increased moisture content in the top layer, whereas, heavy rainfall affected all the layers of the soil. Continuous rainfall had the effect of soil reaching nearly saturated or fully saturated state resulting in Steady State infiltration. Preferential flow was initially reported as the soil consisted of organic matter at different depths of soil profile. The deeper soil layer along all the three locations showed a much higher moisture content being close to the ground water table. From the laboratory tests, more or less the same conclusion was derived based on the wetting front and the moisture content variation curves.

Keywords

Preferential flow, Steady state infiltration

Disciplines

Civil and Environmental Engineering | Civil Engineering | Engineering

Comments

Degree granted by The University of Texas at Arlington

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