Distribution of stable isotopes in arid storms . II. A double-component model of kinematic wave flow and transport

A new mathematical method based on a double-component model of kinematic wave flow and approach assesses the dynamic isotopic distribution in arid rain storms and runoff. This model describes the transport and δ¹⁸O evolution of rainfall to overland flow and runoff in an arid rocky watershed with uniformly distributed shallow depression storage. The problem was solved numerically. The model was calibrated using a set of temporal discharge and δ¹⁸O distribution data for rainfall and runoff collected on a small rocky watershed at the Sede Boker Experimental Site, Israel. Simulation of a reliable result with respect to observation was obtained after parameter adjustment by trial and error. Sensitivity analysis and model application were performed. The model is sensitive to changes in parameters characterizing the depression storage zones. The model reflects the effect of the isotopic memory in the water within the depression storage between sequential rain spells. The use of the double-component model of kinematic wave flow and transport provides an appropriate qualitative and quantitative fitting between computed and observed δ¹⁸O distribution in runoff.