New Dimensions of Hillslope Hydrology

Abstract

Hillslopes are fundamental landscape units that strongly control the processes whereby precipitation or snowmelt is vertically and laterally transported to the streams. They are, in a sense, microcosms of catchments. Understanding and predicting the hillslope response is highly important in terms of flood prediction, transport of nutrients and sediments into surface water bodies, slope stability, and soil-atmosphere-vegetation exchange processes. Through numerous field experiments and numerical studies, much progress has been made in hillslope hydrology in the past decades. However, our ability to extrapolate these findings to ungauged hillslopes and catchments is still very poor (Sivapalan 2005). A common thread that has evolved recently is to search for the underlying principles of hydrological processes instead of characterizing and cataloging the enormous heterogeneity and complexity of rainfall-runoff processes (McDonnell et al. 2007). The aim of this chapter is to provide an overview on today’s conceptual models of processes at the hillslope scale and to examine the factors driving these mechanisms. The focus will be on compiling recent findings on the dominant controls of hillslope runoff processes to meet the need of identifying underlying principles. The chapter closes with thoughts on new dimensions and directions of hillslope hydrology and research avenues to follow for the future.