Influence of temporal variability of rainfall on interception loss. Part I. Point analysis

An interception model that links the temporal variability of rainfall with the storm-based description of the interception process is derived. Analytical formulae for long-term interception loss are obtained for precipitation with statistical characteristics derived from observations. The analysis of the results indicates that the point interception loss is controlled primarily by three time scales: the mean inter-storm arrival time τa, the mean storm duration τr and the time to evaporate a saturated canopy τ0 which depends on canopy water holding capacity Wc and the wet canopy potential evaporation rate EI0, and less importantly, on storm intensity. Additional assumption of rainfall stationarity leads to a relation between long-term interception loss and gross rainfall that requires a very small amount of input data. The interception loss predicted by the analytical model agrees well with that of a Rutter model driven by a synthetic rainfall time series with the same statistics. Using the parameter values estimated from the observed rainfall data in the Amazon and southwestern France, the analytical results predict a long-term interception loss close to that observed.