New insights into factors controlling drainage density in subarctic landscapes

Abstract

Fluvial processes play a crucial role in landscape development in periglacial regions. Geomorphological studies have yielded contrasting inferences about the importance of various environmental factors to drainage density. In this paper, 12 explanatory variables, based on relief, vegetation, soil, and rock type, were used to explain the controlling factors of drainage density in an area of 2880 km2 in subarctic Finland. Analyses were performed at multiple spatial scales (1, 4, 16, and 64 km2) based on two novel statistical methods, namely generalized linear modeling (GLM) and hierarchical partitioning (HP). The results of the GLM and HP analyses were broadly concordant. Most of the variation in drainage density can be explained by soil and vegetation variables. Drainage density increased with proportion of rock and gravel soils and alpine vegetation, and decreased with peat cover. Variables based on topography and rock type explained only a small amount of the variation in drainage density. The results also confirm the profound influence of the spatial scale on the geomorphologic systems: factors influencing drainage density yield different results depending on the spatial scale at which drainage density is analyzed. The large data sets and the use of rigorous statistical techniques at four different scales add the confidence and generality for the present results. © 2007 Regents of the University of Colorado.