GGR217H5 Lecture Notes - Lecture 4: Throughfall
Document Summary
Precipitation falling on vegetation can be portioned into 3 main modes of transport; Before precipitation reaches the ground, must pass through vegetation cover: for urban areas, buildings and other structures act to intercept precipitation. Vegetation cover retains some of this precipitation and returns it to the atmosphere by evaporation or sublimation: this is interception. Direct throughfall: directly to the ground through gaps in the canopy, controlled by lai and canopy storage capacity. Indirect throughfall: dripped from stems, leaves branches, controlled by lai and canopy storage capacity. Canopy storage capacity: how much water leaves and branches can hold before indirect throughfall occurs, determined by size of the tree, area of leaves, and water-holding capacity of leaves. Geometry of vegetation: vegetation/tree type, tree location in a forest. Interception is greater for coniferous that deciduous forests: needles can hold more water than brad leaves due to greater surface area, conifers maintain foliage year-round. Greater snow accumulation in clearings than in the forest.