Feasibility Investigation of Improving the Modified Green–Ampt Model for Treatment of Horizontal Infiltration in Soil

Abstract

Water infiltration in soil is a complex process that still requires appreciation of interactions among three phases (soil particles, water and air) to enable accurate estimation of water transport rates. To simulate this process, the Green–Ampt (GA) model and the Modified Green-Ampt (MGA) model introduced in the paper “A new method to estimate soil water infiltration based on a modified Green–Ampt model” have been widely used. The GA model is based on the hypothesis that the advance of the wetting front in soil under matric suction can be treated as a rectangular piston flow that is instantaneously transformed after passage of the infiltration front, and the MGA model does not contain the influence of pore size change. This cannot accurately reflect the soil moisture change process from unsaturation to saturation. Due to soil stratification and other inhomogeneity, predictions produced with these models often differ widely from observations. To quickly obtain the soil moisture distribution after passage of the wetting front for horizontal infiltration, an improved modified Green–Ampt (IMGA) model is presented, which estimates the soil moisture profile along a horizontal column in a piecewise manner with three functions. A logarithmic function is used to describe the gradual soil saturation process in the transmission zone, and two linear functions are used to represent the wetting zone. The algorithm of the IMGA model for estimating the water infiltration rate and cumulative infiltration is configured. To verify the effectiveness of IMGA model, a lab model test was performed, and a numerical model was built to solve the horizontal one-dimensional Richards equation using the finite–element method. The results show that the IMGA model is more accurate than the GA and MGA models. The horizontal soil moisture profiles obtained by the IMGA model are closer to the measured data than the numerical simulation results. The relative errors of the MGA and IMGA models decrease with an increase in infiltration time, whereas that of the GA model first decreases and then increases with infiltration time. The primary novelty of this study is nonlinear description of soil moisture content distribution, and derivation of unit transfer coefficient.

Monitoring and correction of the stress in an anchor bolt based on Pulse Pre‐Pumped Brillouin Optical Time Domain Analysis

“…In particular, strain information along the rock bolts should be collected to reveal long‐term movements of the rock mass and to allow an operator to take necessary precautions . With the development of optical fiber technology and its use in sensing and measurement, this technology is increasingly used in monitoring stress, overburden deformation, temperature, humidity, and moisture . Lately, optical fibers have been used in monitoring the stress of bolts .…”

Influence of Soil Layers on the Infiltration Rates and Cumulative Infiltration Using Modified Green Ampt Model in the HYDROL-INF Simulation Environment

“…Therefore, researchers worldwide have been searching for new model/tool to satisfy these conditions. A good number of modifications work on GAM were reviewed by Broadbridge and White (1987); Cao et al, 2019;Chen et al, 2019;Zhang et al, 2020). Chu and Morino (2005) introduced the Modified Green-Ampt Model (MGAM) model along with algorithm for computing infiltration into the layered soils.…”

Moving Multi-Front (MMF): A generalized Green-Ampt approach for vertical unsaturated flows

“…Other works in the literature extended or analyzed the GA approximation in various ways, e.g. : infiltration under time varying conditions (Chu, 1978;; layered and heterogeneous soils (Liu et al, 2008;Selker et al, 1999;Yanwei et al, 2015) and (Kacimov et al, 2010); sloping soil surfaces (Chen and Young, 2006) and (Gavin and Xue, 2008); air flow and air compression effects on infiltration (Morel-Seytoux, 1973); non uniform initial moisture (Liu et al, 2008); moisture redistribution after infiltration (Musy and Soutter, 1991); horizontal imbibition instead of vertical infiltration (Cao et al, 2019;Prevedello and Armindo, 2016;Zhang et al, 2019). The latter work by Zhang et al (2019) also proposes a parametric extension of GA based on a piecewise linear approximation of moisture profiles with two linear zones (for horizontal flow).…”