Freshwater resources are at a premium across the world, including many water-limited areas across Australia. Ongoing water level decline in some groundwater systems suggests that the rate of loss may have reached unsustainable levels . However, identifying which factors are primarily responsible for the trend (lack of rainfall-recharge, presence of vegetation, and groundwater pumping) remains challenging using groundwater observations alone. We applied satellite-derived estimates of evapotranspiration (ETa), which, when combined with local rainfall data and field-based groundwater level observations, established a regional water balance spanning 1,500 km(2) and seven groundwater lenses over a 10-year period (2000 - 2010). Assuming that the extent of the freshwater isohaline represents the recharge area for a lens, the water balance suggests that the median annual groundwater recharge rate varied between 226 +/- 92 mm year(-1) (Mikkira) and -162 +/- 194 mm year(-1) (Uley East). Uley South is the most regionally significant lens in the system and recorded a median annual recharge rate of 91 +/- 182 mm year(-1). Overlaying vegetation highlighted the impact of woodland areas on groundwater recharge, where the trees were accessing groundwater to support ETa, provided the water table was <10 m. Areas of grassland demonstrated the highest median groundwater recharge rates of 151 mm year(-1), followed by cropping (133 mm year(-1)) and pasture (95 mm year(-1)). Exploring the resilience of the groundwater system to variations in extraction (pumping) and woodland coverage suggests that resource managers must consider both systematic losses in order to maintain groundwater equilibrium.

Treating drinking water appropriately depends, in part, on the robustness of source water quality risk assessments, however quantifying the proportion of infectious, human pathogenic Cryptosporidium oocysts remains a significant challenge. We analysed 962 source water samples across nine locations to profile the occurrence, rate and timing of infectious, human pathogenic Cryptosporidium in surface waters entering drinking water reservoirs during rainfall-runoff conditions. At the catchment level, average infectivity over the four-year study period reached 18%; however, most locations averaged <5%. The maximum recorded infectivity fraction within a single rainfall runoff event was 65.4%, and was dominated by C. parvum. Twenty-two Cryptosporidium species and genotypes were identified using PCR-based molecular techniques; the most common being C. parvum, detected in 23% of water samples. Associations between landuse and livestock stocking characteristics with Cryptosporidium were determined using a linear mixed-effects model. The concentration of pathogens in water were significantly influenced by flow and dominance of land-use by commercial grazing properties (as opposed to lifestyle properties) in the catchment (p < 0.01). Inclusion of measured infectivity and human pathogenicity data into a quantitative microbial risk assessment (QMRA) could reduce the source water treatment requirements by up to 2.67 log removal values, depending on the catchment, and demonstrated the potential benefit of collating such data for QMRAs.

Invasion by exotic plant species into water-limited environments has the potential to change the ecosystem water balance and may further exacerbate water scarcity issues. Here, we compared ecophysiological traits related to tree water use (sap flux, sapwood density, leaf and soil water potentials) and actual evapotranspiration (ETa) of the invasive Pinus halepensis to native tree and shrub species. We hypothesized that the invasive pine species would possess traits that are consistent with the potential to use more water than native species, which would be supported by higher ETa in areas invaded by pine. We found higher rates of sap flux for the invasive P.halepensis (5.5cmh(-1)) per unit sapwood area compared with the native species (<3.5cmh(-1)). In addition, P.halepensis sapwood was significantly less dense than the sapwood of the native species, suggesting higher sapwood conductivity facilitated the faster sap flux. Comparison of remotely sensed ETa before and after P.halepensis removal within a Eucalyptus camaldulensis stand demonstrated a reduction in ETa by an average of 50(+/- 11 SE)mmyear(-1) in the 2years after removal, relative to the ETa from an undisturbed, intact E. camaldulensis stand. This study suggests that active management of this invasive species should reduce overall ETa losses and thereby exert a positive influence on the availability of soil moisture for groundwater recharge. Copyright (c) 2014 John Wiley & Sons, Ltd.

Cryptosporidium continues to be problematic for the water industry, with risk assessments often indicating that treatment barriers may fail under extreme conditions. However, risk analyses have historically used oocyst densities and not considered either oocyst infectivity or species/genotype, which can result in an overestimation of risk if the oocysts are not human infective. We describe an integrated assay for determining oocyst density, infectivity, and genotype from a single-sample concentrate, an important advance that overcomes the need for processing multiple-grab samples or splitting sample concentrates for separate analyses. The assay incorporates an oocyst recovery control and is compatible with standard primary concentration techniques. Oocysts were purified from primary concentrates using immunomagnetic separation prior to processing by an infectivity assay. Plate-based cell culture was used to detect infectious foci, with a monolayer washing protocol developed to allow recovery and enumeration of oocysts. A simple DNA extraction protocol was developed to allow typing of any wells containing infectious Cryptosporidium. Water samples from a variety of source water and wastewater matrices, including a semirural catchment, wastewater, an aquifer recharge site, and storm water, were analyzed using the assay. Results demonstrate that the assay can reliably determine oocyst densities, infectivity, and genotype from single-grab samples for a variety of water matrices and emphasize the varying nature of Cryptosporidium risk extant throughout source waters and wastewaters. This assay should therefore enable a more comprehensive understanding of Cryptosporidium risk for different water sources, assisting in the selection of appropriate risk mitigation measures.

ABSTRACT The partitioning of precipitation into interception, stemflow and throughfall is an important hydrological process in forested systems, influenced heavily by climate and plant form. This study examined whether the rainfall partitioning pathways reflect the often cited influence of tree morphology, using two species in a semi‐arid karst environment. Eucalyptus diversifolia ssp. diversifolia has a multi‐stemmed habit, smooth bark and true leaves. In comparison, Allocasuarina verticillata has a single trunk, rough bark and long, thin, vertical phyllodes. We hypothesized that multiple stems and a smooth bark would be more effective at generating stemflow compared with single stems with a rough bark surface. To test this, rainfall, throughfall and stemflow were collected over two years, and stemflow funnelling ratios were calculated. The degree of similarity in overall rainfall partitioning for the two species was remarkable; although some divergence was found each month, the partitioning regressions converged. For E. diversifolia , gross rainfall partitioned into interception, throughfall and stemflow averaged 30.9%, 66.4% and 2.7%, respectively. For A. verticillata , rainfall partitioning of gross precipitation into interception, throughfall and stemflow averaged 31.4%, 65.9% and 2.7%, respectively. Maximum stemflow funnelling ratio for E. diversifolia was 74 and for A. verticillata was 147, indicating that water from stemflow is likely to play an important ecohydrological role in this environment. We further compared these findings to 31 global studies and discussed the importance of scale (individual tree vs plot) and canopy cover when reporting or interpreting rainfall partitioning results. Copyright © 2013 John Wiley & Sons, Ltd.

Monitoring source water quality in rivers and catchments remains a key priority not only for catchment managers, but also for water utilities. Here, we applied a best-practice approach to characterise pathogens from the genus Cryptosporidium in rivers used as a drinking water source. Sampling during high flow conditions caused by rainfall run-off determined not only the concentration of Cryptosporidium in water, but also identified the species present and the fraction which remained capable of forming an infection – which to date, has rarely been reported in the literature. The results demonstrate a positive and significant correlation between Cryptosporidium and flow (ρ = 0.756) and turbidity (ρ = 0.631) for all rainfall-runoff events, despite variable source water pathogen concentrations. Twelve Cryptosporidium species/genotypes were identified using molecular techniques, with most Cryptosporidium species detected associated with native and non-native wildlife (comprising 70 % of detections), while livestock-derived Cryptosporidium was detected less frequently (28 % of detections). Importantly, only 3/41 of water samples detected the presence of C. parvum (7 %) and no C. hominis was detected (0 %). Cell culture assays were used to measure the fraction of oocysts and gave an overall infectivity fraction of 3.1 %. To our knowledge, this is the first account which has quantified density, oocyst infectivity and foci species identity from a single environmental water sample.

Protozoan pathogens present a significant human health concern, and prevention of contamination into potable networks remains a key focus for drinking water providers. Here, we monitored the change in Cryptosporidium concentration in source water during high flow events in a multi-use catchment. Furthermore, we investigated the diversity of Cryptosporidium species/genotypes present in the source water, and delivered an oocyst infectivity fraction. There was a positive and significant correlation between Cryptosporidium concentration and flow (rho = 0.756) and turbidity (rho = 0.631) for all rainfall-runoff events, despite variable source water pathogen concentrations. Cell culture assays measured oocyst infectivity and suggested an overall source water infectious fraction of 3.1%. No infectious Cryptosporidium parvum or Cryptosporidium hominis were detected, although molecular testing detected C. parvum in 7% of the samples analysed using PCR-based molecular techniques. Twelve Cryptosporidium species/genotypes were identified using molecular techniques, and were reflective of the host animals typically found in remnant vegetation and agricultural areas. The inclusion of molecular approaches to identify Cryptosporidium species and genotypes highlighted the diversity of pathogens in water, which originated from various sources across the catchment. We suggest this mixing of runoff water from a range of landuses containing diverse Cryptosporidium hosts is a key explanation for the often-cited difficulty forming strong pathogen-indicator relationships. (C) 2014 Elsevier Ltd. All rights reserved.

The flow of precipitation from the surface through to groundwater in karst systems is a complex process involving storage in the unsaturated zone and diffuse and preferential recharge pathways. The processes associated with this behaviour are not well understood, despite the prevalence of karst aquifers being used as freshwater supplies. As a result, uncertainty regarding the ecohydrological processes in this geological setting remains large. In response to the need to better understand the impact of woody vegetation on groundwater recharge, annual evapotranspiration ( ET ) rates and tree water sources were measured for two years above a shallow, fresh karst aquifer. Water use strategies of the co‐occurring Eucalyptus diversifolia subsp. diversifolia Bonpl. and Allocasuarina verticillata (Lam.) L. Johnson were investigated using a monthly water balance approach, in conjunction with measurement of the stable isotopes of water, leaf water potentials and soil matric potentials. The results suggest that it is unlikely groundwater resources are required to sustain tree transpiration, despite its shallow proximity to the soil surface, and that similarities exist between ET losses and the estimated long‐term average rainfall for this area. Irrespective of stand and morphological differences, E. diversifolia and A. verticillata ET rates showed remarkable convergence, demonstrating the ability of these co‐occurring species to maximise their use of the available precipitation, which avoids the requirement to differentiate between these species when estimating ET at a landscape scale. We conclude that the water holding capacity of porous geological substrates, such as those associated with karst systems, will play an important role in equilibrating annual rainfall variability and should be considered when assessing ecohydrological links associated with karst systems. Copyright © 2013 John Wiley & Sons, Ltd.

A groundwater risk assessment was carried out for 30 potable water supply systems under a framework of protecting drinking water quality across South Australia. A semi-quantitative Groundwater Risk Assessment Model (GRAM) was developed based on a "multi-barrier" approach using likelihood of release, contaminant pathway and consequence equation. Groundwater vulnerability and well integrity have been incorporated to the pathway component of the risk equation. The land use of the study basins varies from protected water reserves to heavily stocked grazing lands. Based on the risk assessment, 15 systems were considered as low risk, four as medium and 11 systems as at high risk. The GRAM risk levels were comparable with indicator bacteria-total coliform-detection. Most high risk systems were the result of poor well construction and casing corrosion rather than the land use. We carried out risk management actions, including changes to well designs and well operational practices, design to increase time of residence and setting the production zone below identified low permeable zones to provide additional barriers to contaminants. The highlight of the risk management element is the well integrity testing using down hole geophysical methods and camera views of the casing condition.