Rodríguez Sinobas, Leonor and Gil Rodríguez, María and Sánchez Calvo, Raúl and Losada, Ana and Castañon Lion, Guillermo and Juana Sirgado, Luis and Laguna Peñuelas, Francisco and Benitez Buelga, Javier
Simulation of soil wetting patterns in drip and sdi irrigation. Effects in design and irrigation management variables.
In: "EGU General Assembly 2010", 02/05/2010 - 07/05/2010, Viena, Austria.
Conventional drip irrigation is considered one of the most efﬁcient irrigation systems. Alternatively to traditional surface drip irrigation systems (DI), laterals are deployed underneath the soil surface, as in subsurface drip irrigation (SDI), leading to a higher potential efﬁciency, which is of especial interest in places where water is a limited source. The design and management of DI and SDI systems involve selection of an appropriate combination of emitter discharge rate and spacing between emitters and the inlet pressure and irrigation time for any given set of soil, crop, and climatic conditions, as well as understanding the wetted zone pattern around the emitter. Likewise, water distribution is affected by soil hydraulic properties, initial water content, emitter discharge, irrigation frequency, evapotranspiration and root characteristics. However, complexity arousing of soil water properties and soil proﬁle characteristics means that these are often not properly considered in the design and management of those systems. A better understanding of the inﬁltration process around the discharge point source should contribute to increase water use efﬁciency and thus to reduce the risk of environmental impact of irrigation. In this regard, numerical models have been proved to be a powerful tool to analyze the evolution of the wetting pattern during the distribution and redistribution processes, in order to explore irrigation management strategies, to set up the duration of irrigation, and ﬁnally to optimize water use efﬁciency. Also, irrigation design variables such as emitter spacing and discharge could also be assessed. In this study the suitability of the HYDRUS-2D to simulate inﬁltration process around an emitter during irrigation of a loamy soil with drip and SDI laterals has been addressed. The model was then applied in order to evaluate the main dimensions of the wetted soil volume surrounding the emitter during irrigation. Irrigation uniformity with DI and SDI laterals were determined by ﬁeld evaluations at different inlet head pressures. Results were related with estimations made on water distribution within the soil that were simulated taking into account the emitter discharge at different lateral locations, initial soil water content, soil hydraulic properties and time of irrigation. Conclusions highlight the effect of emitter discharge, emitter spacing, and irrigation time on wetting patterns, and thus solute transport, in both drip and subsurface drip irrigation. The effect of emitter depth was also considered in SDI. Some recommendations for the design and management of these irrigation systems are also provided.