This paper reviews current knowledge of the effect of forest type, ground cover and climate on rainfall partitioning into throughfall, stemflow and interception. It considers the variety and reliability of measurement techniques that have been used and interprets the results of interception studies in relation to methodological, vegetational and climatic factors. The review illustrates that it is difficult to draw general conclusions about interception losses by particular forest types because they almost always depend on the type of rainfall and other meteorological conditions during the study period. Characteristics of a forest that affect interception are not always easy to identify and quantify. Characteristics such as trees/ha, branch angle, the uniformity or lack of uniformity in crown height, the nature and thickness of the bark layer, leaf shape and inclination, and leaf area index will all influence interception. The major difficulty is reliable estimation of throughfall. It is not unusual for measured throughfall to exceed the rainfall value, causing interception to be negative. The difficulty in estimation of throughfall is discussed, while also addressing the need for accurate measurement of rainfall. In forests where stemflow volumes are large enough to significantly influence the interception values, the methodological approach is even more difficult. Measurement of interception on a periodic basis presents fewer problems than estimation on an individual event basis because the variables that affect the values of throughfall and stemflow can change over very short periods, for example the intensity and angle of rainfall, and wind speed and direction. However, carefully conducted event-based studies can quantify the influence of a number of the variables. Copyright © 2000 John Wiley & Sons, Ltd.

Partitioning of rainfall into throughfall, stemflow and interception: effect of forest type, ground cover and climate.

Estimating sparse forest rainfall interception with an analytical model

Evapotranspiration (ET) is the process by which liquid water becomes water vapor and energetically this accounts for much of incoming solar radiation. If this ET did not occur temperatures would be higher, so understanding ET trends is crucial to predict future temperatures. Recent studies have reported prolonged declines in ET in recent decades, although these declines may relate to climate variability. Here, we used a well-validated diagnostic model to estimate daily ET during 1981-2012, and its three components: transpiration from vegetation (Et), direct evaporation from the soil (Es) and vaporization of intercepted rainfall from vegetation (Ei). During this period, ET over land has increased significantly (p < 0.01), caused by increases in Et and Ei, which are partially counteracted by Es decreasing. These contrasting trends are primarily driven by increases in vegetation leaf area index, dominated by greening. The overall increase in Et over land is about twofold of the decrease in Es. These opposing trends are not simulated by most Coupled Model Intercomparison Project phase 5 (CMIP5) models, and highlight the importance of realistically representing vegetation changes in earth system models for predicting future changes in the energy and water cycle.

https://biblio.ugent.be/publication/7033679/file/7033688.pdf

Multi-decadal trends in global terrestrial evapotranspiration and its components

Modelling interception loss for two sparse eucalypt and pine forests in central Portugal using reformulated Rutter and Gash analytical models

A review of rainfall interception modelling

Rainfall interception in the Tai Forest, Ivory Coast: Application of two simulation models to a humid tropical system

Infiltration experiments have been performed at three sites along a well-known catena under virgin tropical rain forest using a portable sprinkling infiltrometer.



Experimentally determined infiltration curves are presented. Infiltration curves are also simulated on the basis of the Mein-Larson equation. The parameters for this model have been obtained from the infiltration curves (saturated conductivity) and simple soil moisture determinations (fillable porosity). The agreement between experimentally determined and modelled infiltration is reasonable, provided (a) saturated conductivity as derived from the experimental data is corrected, (b) a storage parameter, also derived from the experimental data, is added to the Mein-Larson model, and (c) the decline in soil porosity with depth is either small or occurs abruptly at shallow depth.



Comparison of observed infiltration rates with rainfall intensity shows that Horton Overland Flow has to occur naturally at least on the middle and lower section of the catena.



Despite the fact that most parameters can be estimated in principle from basic soil data, it remains advisable to obtain sprinkling infiltrometer field measurements, because of soil variability due to dynamic surface conditions, macroporosity, air entrapment, and irregularity of the wetting front.

A. Wierda

Papers

Rainfall interception in the Tai Forest, Ivory Coast: Application of two simulation models to a humid tropical system

Infiltration at the Tai rain forest (Ivory Coast): measurements and modelling