Determination of Micro-Droplet Flux in Forest and Its Contribution to Interception Loss of Rainfall: An Experimental and Theoretical Perspectives

Abstract

The new method was presented in this article, and a case study was provided to demonstrate its applicability (capable to explain the extraordinarily high interception loss). By introducing tiny raindrops that have been crushed during rainfall, a novel explanation for forest interception has been put forth. At the Okunoi Experimental Station in Tokushima, Japan, eight rainfall events were used to test the proposed formulas for the aerodynamic diffusion and transfer of both vapour and micro-droplets from canopy to upper air.  Contributions from droplet transfer were 0.9-58.2 times of contributions from vapour transfer, taking a majority portion in total interception loss. Accounting only the vapour transfer or evaporation loss as estimated by Penman equation was not able to account for actual interception loss. In the two instances of intense rainfall, the micro-droplets flux component played a significant role and even entirely compensated for the interception that occurred in October 2004. The fact that droplet flux could support a high interception rate even when the air was almost vapour-saturated and the vapour flux was zero was a significant discovery. This suggested strategy was tested in an attempt to address the challenging inquiry regarding noticeably high interception rates. The micro-droplet flux component played a significant role in the two instances of intense rainfall and entirely compensated for the interception that occurred in October 2004. Even when the air was almost vapour-saturated and the vapour flux was zero, the droplet flux could support a high interception rate. This method offered a fresh justification for the astronomically high interception rates.