Simulating wetting front in drip irrigation using HYDRUS-2D

Subject Areas : Farm water management with the aim of improving irrigation management indicators

Neda  Khanmohamadi ¹ (PhD student, Department of Water Engineering, Urmia University, Urmia 57135-165, Iran)
Sina  Besharat ² (Assistant Professor, Department of Water Engineering, Urmia University, Urmia 57135-165, Iran)

Received: 2012-12-15 Accepted : 2013-06-02 Published : 2013-09-22

Keywords: drip irrigation, HYDRUS-2D software, soil moisture pattern, wetting front,

Abstract :

Quantitative perception of soil hydraulic behavior has important impact on optimal soil and water resources conservation. Understanding of this behavior in drip irrigation system is a real task for researchers. The geometry of moisture pattern created by trickles in soil is one of the important criterions in drip irrigation system. Several important parameters such as soil hydraulic functions, drip discharge and irrigation time directly influence the dimensions of created wetting front.  The objective of this study was to determine the wetting front dimensions created by point sources. For examining HYDRUS-2D software capability, a T-tape drip irrigation method with 2.388 cm/hr discharge and maximum depth of 70 cm was conducted in the Urmia University experimental field. At the end of irrigation experiment, the water distribution condition in soil was determined by gravimetric soil sampling method. When performance of simulation model confirmed to be accurate enough for simulation purposes, six different discharges with trickle function of maximum 30 h, was conducted by the software. Some simple relationships were obtained by using Buckingham π theorem. These equations determinate the depth and maximum diameter of soil by using soil hydraulic conductivity, drip discharge and irrigation time. The obtained correlation coefficients (0.993 and 0.970) and mean absolute error values (1.177 and 1.706) for determining the depth and maximum diameter of soil confirmed the capability of these semi empirical equations for calculating moisture pattern geometry dimensions. Consequently, these derived equations can be used for design and optimal management of drip irrigation system in the studied conditions.