Simulation of infiltration from porous clay pipe in subsurface irrigation

Abstract

Advances in the traditional method of subsurface porous clay pipe irrigation rely on knowledge of the distribution of water in the soil. Knowing the relationships among the hydraulic and physical parameters in the system is important for both the design and management of the system. To simulate the infiltration from the porous clay pipe and predict the wetted zone geometry in the soil, a computer model is developed herein. Laboratory experiments were conducted on soil samples representing two different soil textures in a specially designed bin to understand the flow phenomenon and to validate the developed model. In a given soil texture, the installation depth of the pipe and the volume of water applied in the soil are the major factors affecting the wetted zone. The relationships among various parameters, namely lateral spacing, installation depth, irrigation run time, hydraulic conductivity of the body of the pipe, and hydraulic head in the system, were established using the developed model. Key words infiltration; porous clay pipe; subsurface irrigation; wetting front; soil texture; hydraulic conductivity; matric potential; unsaturated flow; model simulation Simulation de l'infiltration à partir d'un tuyau d'argile poreux en irrigation souterraine Résumé Les améliorations apportées à la méthode traditionnelle d'irrigation souterraine par tuyaux d'argile poreux dépendent de la connaissance de la distribution de l'eau dans le sol. Il est important de connaître les relations qui existent entre les paramètres hydrauliques et physiques du système, à la fois pour la conception et la gestion du système. Pour simuler l'infiltration à partir du tuyau d'argile poreux et prédire la géométrie de la zone humide dans le sol, un modèle de simulation informatique a été développé. Des expériences en laboratoire ont été conduites sur des échantillons de sol présentant deux textures différentes dans un silo spécialement conçu pour comprendre le phénomène d'écoulement et pour alimenter la validation du modèle. Dans une texture de sol donnée, la profondeur d'installation du tuyau et le volume d'eau déversé dans le sol sont les principaux facteurs à affecter la zone humide. Les relations entre les différents paramètres que sont l'espacement latéral, la profondeur d'installation, la durée d'irrigation, la conductivité hydraulique du tuyau et la charge hydraulique dans le système, ont été établies en utilisant le modèle développé.

Simulations of water movement and solute transport through different soil texture configurations under negative‐pressure irrigation

“…Subsurface irrigation can effectively improve water use efficiency by directly supplying water into the crop root zone (Ashrafi, Gupta, Babel, Izumi, & Loof, ). The process in which the pressure of the water supply is controlled to a negative value relies on soil matric suction (Moniruzzaman, Fukuhara, Ito, & Ishii, ; Moniruzzaman, Fukuhara, & Terasaki, ) and is called negative‐pressure irrigation (NPI).…”

“…The emitter is a pipe that is made of clay, and water moves into the soil through the emitter; the wall of the emitter has a certain thickness, and thus, hydraulic conductivity of the emitter likely affects water movement significantly in NPI. For given values of the irrigation run time, the hydraulic head in the system, and the installation depth, the wetted zone may display increases with increases in hydraulic conductivity of the pipe in subsurface irrigation (Ashrafi et al, ). Siyal and Skaggs () assumed that the hydraulic conductivity value of the pipe material was 0.05 cm/d in simulations of soil‐wetting patterns under porous clay pipe subsurface irrigation.…”

Experimental Study on Water Balance in a Negative Pressure Difference Irrigation System

“…Most of the past studies on NPDI (For example, Kato et al 2) , Tanigawa et al 3) , Ashrafi et al 4) , Siyal et al 5) ) were dealt with percolation around a porous pipe installed horizontally in soil. On the other hand, the percolation around a vertically installed porous pipe has been hardly performed except Peifu et al 6) and Akhoond et al 7) .…”

Steady Flow from an Array of Subsurface Emitters: Kornev’s Irrigation Technology and Kidder’s Free Boundary Problems Revisited

“…The obtained pairs of (d, m) and the range of variations of the vertical component of the Darcian velocity vector along I 1 I 2 are: (60, 10 cm), (13-14.6 cm/day); (50, 30 cm), (22.2-25.2 cm/day); and (43, 90 cm), (27.3-32.2 cm/day), respectively. If p i is decreased to negative values (as in Ashrafi et al 2002), then the water table drops further, Q increases and the saturated zone around the emitter shrinks (and may even convolute into Philip's "saturated bulb").…”

“…6i) illustrates the water table position, in particular, d = 46 cm, m = 40 cm. Similarly to Ashrafi et al (2002) Siyal andSkaggs (2009), andWang et al (2017), we can include a thin pipe wall made of a low permeable clay.…”