ATMOSPHERIC DEPOSITION TO WATERSHEDS IN COMPLEX TERRAIN

Single collection stations for wet or bulk deposition are generally in adequate to describe atmospheric inputs to watersheds in complex terra in. Atmospheric deposition is delivered by wet, dry and cloud depositi on processes, and these processes are controlled by a wide range of la ndscape features, including canopy type and structure, topographic exp osure, elevation and slope orientation. As a result, there can be a ve ry high degree of spatial variability within a watershed, and a single sampling point, especially at low elevation, is unlikely to be repres entative. Atmospheric inputs at the watershed scale can be calculated from the whole watershed mass balance if the outputs and within-waters hed sources and sinks are known with sufficient accuracy. Alternativel y, indices of atmospheric deposition such as Pb accumulation in the fo rest floor and SO42- flux in throughfall can be used to characterize p atterns of total deposition, and these indices can be used to model de position to the entire watershed based on known landscape features suc h as elevation and canopy type. (C) 1997 by John Wiley & Sons, Ltd.