Applicability of analytical solutions for flow from point sources to drip irrigation management

The design and management of drip irrigation systems requires understanding of water distribution and dynamics within the wetted soil volume. This information can be obtained by means of analytical or numerical solutions of the multidimensional Richards equation. Though steady-state solutions have been advocated as design tools for drip irrigation, very little information about their performance under practical field conditions is available. The objective of this study was to evaluate the applicability of analytical solutions for steady and transient flows from point sources to practical drip irrigation management. The emphasis was on the adaptive and dynamic aspects of management vs. conservative design considerations. Experiments were carried out in containers and in the field to determine steady-state attainment rates and to provide information on spatial and temporal dynamics of water content and matric potential during irrigation cycles. The main results were: (i) analytical solutions for steady and transient flow conditions predicted reasonably well measured distributions of water content and matric potential in the absence of plants (ii) steady flow conditions were seldom realized under practical drip irrigation; (iii) transient flow solutions provided a more realistic description of soil water dynamics; and (iv) introducing uptake terms into transient analytical solutions provided a simple and effective framework for capturing soil water dynamics in the presence of plant roots