The limited impact of vegetation on the water balance of mine waste cover systems in semi‐arid Australia

Abstract

In (semi‐)arid environments, mine waste cover systems aim to minimize drainage into underlying hazardous wastes by maximizing evaporation from soil and transpiration from vegetation. We estimated the evapotranspiration (ET) for an area occupied by characteristic semi‐arid native Australian plant species. Using an open top chamber, we measured diurnal and daily ET of two plant species – Senna artemisioides (silver cassia) and Sclerolaena birchii (galvanized burr) – after a simulated rainfall event, as well as evaporation (E) from bare soil. Both ET and E decreased with increasing time after initial watering. However, we observed different temporal patterns for daily ET and E, indicating that S. artemisioides and S. birchii are relatively intensive and extensive water exploiters, respectively. We found a strong positive linear relationship between ET or E and the atmospheric water demand represented by the vapour pressure deficit. This correlation was more pronounced in the morning than in the afternoon, indicating a diminishing water supply from the soil associated with a declining unsaturated hydraulic conductivity of the soil in the afternoon. We used the estimated values of ET and E to project the effect of species composition on plot ET in relation to total vegetation coverage. Although both species survive and grow under the dry conditions at the study site, their influence on plot ET was rather small because of the low vegetation coverage. On this basis, we conclude that the relevance of plants on ET cover systems is small under such water‐limited conditions of semi‐arid and arid climates. Copyright © 2014 John Wiley & Sons, Ltd.

Shoot water content and reference evapotranspiration for determination of crop evapotranspiration

“…However, the gains in soil moisture content through canopy cover were negated by the absorption of more moisture to sustain this heavy vegetative growth and increased transpiration. This led to the overall decline in soil moisture under SB20 (Table 2) Arnold et al (2015) and Yan et al (2014) also reported the influence of minimum canopy as the cause for increased evaporation. Evaporation as a factor of ETc had minimum fluctuation as it is dependent on solar radiation (Wang and Liu, 2007).…”

Ecosystem Management Along Ephemeral Rivers: Trading Off Socio‐Economic Water Supply and Vegetation Conservation under Flood Regime Uncertainty

“…But water exploitation and ecosystem management can be designed such that the original ecological interactions are preserved and species coexistence is maintained (Emmert et al ., ). Moreover, groundwater yield can be increased by promoting water conservative species that transpire less water (Rodriguez‐Iturbe et al ., ; Arnold et al ., ; Gwenzi et al ., ).…”

Effectiveness of Grassland Vegetation on a Temporary Capped Landfill Site

“…Temporary capping systems regularly consist of a recultivated layer, a drainage layer, and a sealing layer consisting of mineral substrates or in combination with polymers [6]. The major aim of the recultivated layer is to restrain landfill gas migration and to minimise leachate generation (precipitation contaminated with heavy metals or polycyclic hydrocarbons) by a high water storage capacity in combination with a distinct evapotranspiration rate from the vegetation and soil surface [3,7]. Therefore, the choice of a locally adapted vegetation type (grassland, shrubs, forest) is essential to ensure high evapotranspiration rates (grassland: 450-550 mm year À1 ), a quick vegetation establishment (erosion protection, slope stability), and avoid deep shrinkage-induced cracking (capillary rise from deeper horizons) and rooting to protect the sealing layer as last barrier above the waste body depending on the thickness of the recultivated layer [4,[8][9][10].…”