Development and analysis of a kinematic wave approach for estimating potential water yields of microcatchment irrigation systems on natural soils

Abstract

A conceptual and experimental analysis of rainfall-runoff hydraulics on a natural microcatchment was conducted in the Negev Desert, Israel. The kinematic wave equations were utilized as a physically-based, hydrodynamic model because they can mathematically describe the simultaneous processes of rainfall, infiltration, and runoff. Model inputs are rainfall and infiltration rates, catchment response time, and flow velocity. A series of experiments was conducted over a range of rainfall intensities using a rainfall simulator. The slope of the infiltration curve, time when runoff begins, time to peak, and peak discharge were found to be dependent on rainfall intensity. Owing to its effects on infiltration, the highest rainfall intensity did not produce the largest water yield. Velocity was found to be independent of flow depth and a linear function of rainfall intensity. The concept of constant velocity linearized the kinematic wave equation and enabled analytic solutions to be developed. These solutions are not unique; graphical fitting or multiple regression should be used to identify optimal parameter values. Model equations can be used to calculate the catchment size necessary to supply the water requirements of a given tree species and can be applied in regions where computer use is not feasible.