Intra‐storm evaporation as a component of canopy interception loss in dryland shrubs: observations from Fowlers Gap, Australia

Abstract

Abstract:Interception losses from the canopies of dryland plant taxa remain poorly understood, especially the relative contributions of intra-storm and post-storm evaporative losses. Employing a new measuring apparatus, this study uses low-intensity simulated rain, matched to the properties of local rain, to explore interception processes in bluebush shrubs at an Australian dryland site. Five shrub specimens were exposed to simulated rain for 60-90 min. Experiments were repeated at three rainfall intensities (10, 15, and 20 mm h 1 ). Canopy evaporation was found from the difference between the flux of water delivered to the shrub and the flux of throughfall, once equilibrium had been established. The results show that evaporation from the wet foliage during rain proceeds at an average rate of 3Ð6 mm h 1 . This figure is for relatively cool spring-season conditions; evaporation rates in hot summer conditions would be larger. Intra-storm evaporation is shown to exceed post-rain evaporation from interception storage on the shrubs, and this differentiates dryland shrub interception processes from those of the betterstudied wet forest environment. Implications of the high dryland shrub canopy evaporation rates for aspects of dryland ecology are highlighted.

A review of concentrated flow erosion processes on rangelands: Fundamental understanding and knowledge gaps

“…The percentage of event rainfall captured by vegetation and associated ground cover generally decreases as rainfall intensity increases (Carlyle-Moses, 2004;Owens, Lyons, & Alejandro, 2006). For low-intensity, short-duration rainfall events, most of the precipitation is captured by plant canopies, litter, and other ground cover and is lost to evaporation (Dunkerley, 2008;Owens et al, 2006). Water input during highintensity or prolonged rainfall events usually exceeds interception storage capacity, resulting in delivery of water to the ground surface via throughflow and stemflow (Carlyle-Moses, 2004; D. Dunkerley, 2000;D.L.…”

Rehabilitation of arid rangelands: Intensifying water pulses from low-intensity winter rainfall

“…The degradation is typically characterised by a loss of perennial plant cover (Whisenant, 2002), which increases the amount and connectivity of bare ground. This leads to soil crusting and compaction, a decline in water infiltration and increased runoff (du Toit et al, 2009;Mills and Fey, 2004;Snyman and du Preez, 2005). Furthermore, higher temperatures of the exposed soil (Rietkerk et al, 2000;Snyman and du Preez, 2005) accelerate the evaporative loss of soil water.…”

“…Along with the size and intensity of rainfall events, the fate of rainwater is also influenced by the weather conditions during and after rainfall events (Dunkerley, 2008;Loik et al, 2004). Winter rainfall is produced by low pressure systems resulting in chilly and windy weather for several days (Desmet and Cowling, 1999), which may influence the mechanisms by which rehabilitation treatments affect soil water status.…”

Characteristics of rainfall events in regional climate model simulations for the Czech Republic

“…Studies looking in detail into individual rainfall event characteristics in RCM simulations are missing despite the fact that such characteristics of heavy rainfall events as event depth, duration, or intensity are relevant for urban hydrology (e.g. Einfalt et al, 1998;Barbosa et al, 2012;Willems et al, 2012) and determine characteristics of various hydrological processes as overland flow generation and shape of the resulting hydrograph (Singh, 1997), soil moisture dynamics (Wang et al, 2008;He et al, 2012), infiltration (Ran et al, 2012), rainfall erosion (Wischmeier and Smith, 1978), evaporation (Dunkerley, 2008a), storm sewer flow rates and direct runoff (Schilling, 1991;Giulianelli et al, 2006). Therefore considering these individual rainfall event characteristics is important also in RCM evaluation studies, which has been highlighted already by, for example, Westra et al (2014), who suggested (among other things) to focus on (spatial structure and) temporal evolution of rainfall events and their timing and intermittency.…”