Drip-Irriwater: Computer software to simulate soil wetting patterns under surface drip irrigation

Abstract

Drip irrigation provides greater efficiency in terms of water usage and energy. These factors are very important in light of the current competition for water resources between the various users, especially in the Mediterranean region due to water scarcity. The shape and dimensions of the volume of wet soil below the emitter are some of the most influential variables in the optimal design and management of drip irrigation systems. This paper presents Drip-Irriwater, a code for determining soil wetting patterns under a single emitter in order to suggest planning factors for a drip irrigation system. The code solves Richards’ equation using the finite difference method subject to appropriate boundary conditions for drip irrigation. The boundary conditions on the surface of the soil allow us to consider forming a pond under the emitter. The user interface enables users to simply enter the input parameters (discharge rate, soil type and horizons, irrigation time, initial water content and total simulation time). The code then displays the soil water content and pressure heads, enabling a visual distinction between the wetted radius and depth, the parameters required for subsequent drip irrigation design. The results obtained with Drip-Irriwater were compared with those obtained with HYDRUS and with results from field tests carried out on three different soil types. The soil water distribution, as well as the wetted radius and depth, calculated from the Drip-Irriwater and HYDRUS code, were very similar. Field tests conducted to verify the results of the code confirmed that Drip-Irriwater gave a good approximation of the wetted radius and depth, and could therefore be used to design a drip irrigation system.