Modelling interception loss using the revised Gash model: a case study in a mixed evergreen and deciduous broadleaved forest in China

Abstract

Interception loss accounts for a substantial portion of incident precipitation and evapotranspiration in forest ecosystems. Hence, identifying its magnitude is crucial for our understanding of biogeochemical cycling and related hydrological processes. In this study, gross rainfall partitioning into interception loss, throughfall and stemflow were measured and modelled using the revised Gash model for a mixed evergreen and deciduous broadleaved forest over the 2014 growing season. Field survey results revealed that interception loss accounted for 14.3% of gross rainfall, while understory rainfall was 84.8% throughfall and 0.9% stemflow. The revised Gash model produced a fairly good agreement between observed and estimated rainfall partitioning. The model underestimated interception loss by only 6.6%, while throughfall and stemflow were also slightly misestimated. Hence the interception loss predictions from the model were robust and reliable for this mixed evergreen and deciduous broadleaved forest. As quantified by the model, the vast majority of interception loss occurred as evaporation from the canopy under saturated conditions: 54.9% evaporated during rainfall events, and 38.3% after rainfall ceased. The sensitivity analysis indicated that predictions from the revised Gash model were most affected by changes in canopy storage capacity (S), followed by the mean evaporation rate (Ē) during rainfall events, the mean rainfall rate ( trueR¯) and last canopy cover (c). Model predictions were least sensitive to trunk parameters (St and pt). Copyright © 2016 John Wiley & Sons, Ltd.

Global canopy rainfall interception loss derived from satellite earth observations

“…Previous studies have concluded that interception is linearly related to the P g amount, and the linear fitting equation varies site to site (Saito et al, 2013;Soto-Schonherr & Iroume, 2016;Staelens et al, 2008;Su, Zhao, Xu, & Xie, 2016;Sun, Onda, & Kato, 2014). Besides the P g amount, the rain rate, which is the ratio of P g amount to rainfall hours, also impacts the interception loss (Cuartas et al, 2007;Zhang et al, 2016).…”

Application of Copula Functions for Rainfall Interception Modelling

“…More specifically, all vegetation periods (e.g., at least one leafed and one leafless period) should be recorded in order to detect the seasonal variability in rainfall interception. Different statistical methods (e.g., [9,12,17,22]) and other model types (e.g., [4,[23][24][25][26]) have already been used and developed to evaluate the influence of different variables on rainfall interception, and also to predict it. Some models are quite complex, requiring a large number of parameters.…”

Modelling of rainfall partitioning by a deciduous shrub using a variable parameters Gash model

“…As stemflow is rainfall captured by canopy and running down the stem, it would reduce if canopy coverage reduces. A reduction in coverage also means that the free throughfall coefficient increases, which could be assumed to be one minus the coverage (Su, Zhao, Xu, & Xie, ). The change in coverage is about −7.37% to 5.26% compared with the average value, which could lead to about −4.39% to 3.13%, −8.70% to 6.21%, and −17.69% to 12.62% estimated errors in interception, stemflow, and throughfall, respectively.…”

“…As stemflow is rainfall captured by canopy and running down the stem, it would reduce if canopy coverage reduces. A reduction in coverage also means that the free throughfall coefficient increases, which could be assumed to be one minus the coverage (Su, Zhao, Xu, & Xie, 2016).…”