Canopy interception mapping using field measurements and high-resolution airborne imagery - case study for a region in Vorarlberg, Austria

Abstract

The process of rainfall interception by canopies plays an important role in the hydrological cycle. The fraction of rainfall which is intercepted is largely dependent on species-specific vegetation properties, such as leaf- and branch architecture and canopy structure and - density. Because these vegetation properties spatially vary, canopy interception is a spatially variable process. However, these species-specific vegetation properties are often not, or insufficiently included in hydrological models which focus for example on rainfall-runoff processes, soil moisture balances, transpiration and groundwater recharge from rainfall. This could lead to serious modelling uncertainties and - mistakes. This study aimed at improving an existing spatial interception mapping approach by including relations between species-specific vegetation properties and interception. In order to achieve this goal, a two-fold method was applied. First, the influence of species-specific differences of leaf-and canopy structures on the interception process was studied. Fieldwork on branch- and plot-scale was performed in a study region in Vorarlberg (Austria) to find relations between the vegetation properties and interception. Secondly, the ability of a high-resolution remote sensing imagery based model to estimate the spatial variability of canopy interception on regional scale was studied when these species-specific relations were implemented. Promising fieldwork results were gained which describe the relations between vegetation properties and interception per species. Due to these results, it was possible to model spatial variability of canopy interception for the study region in Vorarlberg, thereby taking species-specific vegetation properties into account. Although the results contribute to the improvement of the current approach to quantitatively estimate spatial variability of canopy interception on regional scale, the method needs to be improved and more research is needed in this field.