Hydrogeomorphic Processes in Temperate and Tropical Forests: Effects of Land Use and Scale



The science of hydrogeomorphology has evolved during the past few decades to include not only the coupling of hydrologic and geomorphic processes but also the spatial and temporal interactions of these processes. Bioclimatic factors play an important role in determining which hydrologic and geomorphic processes dominate in various environments and how these processes evolve and distribute in time and space. Herein, sediment production and transport are discussed as examples of important hydrogeomorphic phenomena at different spatial and temporal scales in the context of climate, forest cover, hydrology, and geomorphic setting. Examples are presented that illustrate the dominant hydrogeomorphic processes in steep (typical slope gradients >30°) humid tropical and temperate forests. Landslides contribute substantial sediment loads to streams, particularly in steep temperate forest terrain; however, the timing between the mass wasting event on the hillslope and the delivery and mobilization of the sediment in the channel can be highly variable. Linkages between surface erosion on hillslopes and sediment response in streams are more direct if connected pathways exist. The connectivity of sediment sources with flow pathways in catchments can be greatly enhanced by land uses (particularly unpaved roads and trails) that compact and disturb soils and redistribute water onto susceptible landforms.