Hydrological response in a savanna hillslope under different rainfall regimes

Abstract

Savannas are currently experiencing extensive population and agricultural water resource pressure globally (Rockström et al. 2014). Because we are now moving into an era of adaptive management of ecosystems where information on state change thresholds is a prerequisite for their sustained management, it is necessary to invest in understanding the biophysical processes that maintain these systems. In savanna landscapes, soil water is the direct link between precipitation and ecological patterns (Weltzin et al. 2003). The co-domination by trees and grasses is bound by soil water availability, a key factor in establishing form and function. Therefore, spatial soil moisture dynamics is a crucial link in the equilibrium between climate, soil and vegetation in these systems (Rodriguez-Iturbe et al. 1999). The resulting hydrological processes contribute to the biophysical template of these semi-arid systems, controlling the distribution of water and other resources along a continuum within the landscape, which often comprises compound effects of non-linear relationships and thresholdtriggered responses. Given this complexity, novel interdisciplinary approaches should be sought to understand hydrological processes in such heterogeneous landscapes (Troch et al. 2008). Moreover, inter-disciplinarity is increasingly valuable for successful landscape management, given the emphasis on hydrological connectivity at landscape scale (Michaelides & Chappell 2009).