poster - International Conference of Agricultural Engineering

Is Imaging Analysis Quantifying the Impacts of Solute Transport? A
New Approach to Assess Wetting Front Map under Trickle Irrigation
El-Sayed E. Omran 1 *, Gamal M. ElMasry 2 and Mohamed A. Rashad 2
1 Soil and Water Department, Faculty of Agriculture, Suez Canal University, Egypt.
2 Agricultural Engineering Department, Faculty of Agriculture, Suez Canal University, Egypt.
* Corresponding author. E-mail: e.omran@scuegypt.edu.eg
Abstrat
To investigate solute transport in soils, detailed information about the spatial distribution of
solutes is required. Many attempts have been made to determine wetting pattern under
trickle irrigation using sophisticated mathematical and numerical models. These methods
require detailed information concerning soil physical properties besides too complicated
calculations for routine use. This study was carried out to investigate the feasibility of using
image-analysis technique to derive soil wetting area and depth and to develop an image
processing algorithm to derive soil wetting front map. A digital image analysis technique is
proposed as a potential alternative method for visualizing and quantifying flow patterns in
soils with a high spatial resolution. The method was applied in two soil types (sandy and
sandy clay loam). The results of the proposed method showed that the image analysis
technique gives reasonably good estimates of the wetting front map (depth and area). This
potential approach to characterize flow patterns allows an objective comparison of soil
infiltration patterns in the field. This proposed method could be generalized to quantify and
easily derive soil flow patterns which are an important issue for precision irrigation farming
and agricultural management.
Key words: solute transport, image analysis, trickle irrigation, precision irrigation.
Introduction
Agricultural management, soil remediation and groundwater protection require ways of
quantifying solute transport processes. Soil heterogeneity is responsible for the difficulty in
predicting the movement of mass (solids, liquids and gases) in field situations at most scales
[Lin & Zhou, 2008; Jamieson et al., 2002]. Solute transport in the unsaturated zone which is
difficult to predict remains an important research topic in soil science [Vanderborght et al.,
2002 and Omran, 2008]. The concern is mainly about the impact of solute transport on the
water use efficiency. One of the methods that can provide high water use efficiency is trickle
irrigation but only if the system is designed to meet the soil and plant conditions [Phene,
1995; Cook et al., 2006].
One of the pre-requisites for better trickle irrigation design is more information about the
moisture distribution patterns. Trickle irrigation involves applying low quantity of water at low
pressure via an emitter. The wetted-soil volume under a point source trickle systems must be
known to determine the total number of emitters required to wet a specific volume of soil to
meet plant water requirements [Ainechee et al., 2009]. The volume of wetted soil and its
shape is primarily a function of the soil texture and structure, application rate, and number of
emitters. So, it is essential to know the effect of the water application technique (discharge
rate, continuous or intermittent application) on the amounts of water distributed to the various
parts of the wetted soil volume [Elmaloglou & Diamantopoulos, 2007]. Water trickling from a
point source takes place in the soil and moves downwards and sideways. As a result, three
dimensional transient flows occur.
There has been much speculation on the shape of the wetted soil volume. One of the
important criteria when designing trickle irrigation systems is the geometry of the wetting
pattern generated by the emitters [Cook et al., 2006]. Many attempts have been exerted to
determine the wetting pattern under trickle irrigation using sophisticated mathematical and