Characterization of surface water – groundwater interaction in riverbank filtration (RBF) systems is of decisive importance to drinking water utilities due to the increasing microbial and chemical ...contamination of surface waters. These interactions are commonly assessed by monitoring changes in chemical water quality, but this might not be indicative for microbial contamination. The hydrological dynamics of the infiltrating river can influence these interactions, but seasonal temperature fluctuations and the supply of oxygen and nutrients from the surface water can also play a role. In order to understand the interaction between surface water and groundwater in a highly dynamic RBF system of a large river, bacterial abundance, biomass and carbon production as well as standard chemical parameters were analyzed during a 20 month period under different hydrological conditions. In the investigated RBF system, groundwater table changes exhibited striking dynamics even though flow velocities were rather low under regular discharge conditions. Bacterial abundance, biomass, and bacterial carbon production decreased significantly from the river towards the drinking water abstraction well. The cell size distribution changed from a higher proportion of large cells in the river, towards a higher proportion of small cells in the groundwater. Although biomass and bacterial abundance were correlated to water temperatures and several other chemical parameters in the river, such correlations were not present in the groundwater. In contrast, the dynamics of the bacterial groundwater community was predominantly governed by the hydrogeological dynamics. Especially during flood events, large riverine bacteria infiltrated further into the aquifer compared to average discharge conditions. With such information at hand, drinking water utilities are able to improve their water abstraction strategies and react quicker to changing hydrological conditions in the RBF system.
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•Bacteria in groundwater in RBF systems are influenced by the infiltrating river.•Fluctuations in bacterial variables are linked to the hydrological dynamics.•An increased influence was observed during flood events.•During flood events the infiltration extends further into the aquifer.•Increases in bacterial numbers and activity are not caused by a nutrient input.
Nature-based solutions (NbS) offer significant potential for climate change adaptation and resilience. NbS strengthen biodiversity and ecosystems, and premise approaches that centre human wellbeing. ...But understandings and models of wellbeing differ and continue to evolve. This paper reviews wellbeing models and thinking from Aotearoa New Zealand, with focus on
Te Ao Māori
(the Māori world and worldview) as well as other Indigenous models of wellbeing from wider
Te Moana-nui-a-Kiwa
Oceania. We highlight how holistic understandings of human-ecology-climate connections are fundamental for the wellbeing of Indigenous peoples of
Te Moana-nui-a-Kiwa
Oceania and that they should underpin NbS approaches in the region. We profile case study experience from Aotearoa New Zealand and the Cook Islands emerging out of the Nature-based Urban design for Wellbeing and Adaptation in Oceania (NUWAO) research project, that aims to develop nature-based urban design solutions, rooted in Indigenous knowledges that support climate change adaptation and wellbeing. We show that there is great potential for nature-based urban adaptation agendas to be more effective if linked closely to Indigenous ecological knowledge and understandings of wellbeing.
The main objective of the paper is to understand the contributions to the uncertainty in low-flow projections resulting from hydrological model uncertainty and climate projection uncertainty. Model ...uncertainty is quantified by different parameterisations of a conceptual semi-distributed hydrologic model (TUWmodel) using 11 objective functions in three different decades (1976–1986, 1987–1997, 1998–2008), which allows for disentangling the effect of the objective function-related uncertainty and temporal stability of model parameters. Climate projection uncertainty is quantified by four future climate scenarios (ECHAM5-A1B, A2, B1 and HADCM3-A1B) using a delta change approach. The approach is tested for 262 basins in Austria. The results indicate that the seasonality of the low-flow regime is an important factor affecting the performance of model calibration in the reference period and the uncertainty of Q95 low-flow projections in the future period. In Austria, the range of simulated Q95 in the reference period is larger in basins with a summer low-flow regime than in basins with a winter low-flow regime. The accuracy of simulated Q95 may result in a range of up to 60 % depending on the decade used for calibration. The low-flow projections of Q95 show an increase of low flows in the Alps, typically in the range of 10–30 % and a decrease in the south-eastern part of Austria mostly in the range −5 to −20 % for the climate change projected for the future period 2021–2050, relative the reference period 1978–2007. The change in seasonality varies between scenarios, but there is a tendency for earlier low flows in the northern Alps and later low flows in eastern Austria. The total uncertainty of Q95 projections is the largest in basins with a winter low-flow regime and, in some basins the range of Q95 projections exceeds 60 %. In basins with summer low flows, the total uncertainty is mostly less than 20 %. The ANOVA assessment of the relative contribution of the three main variance components (i.e. climate scenario, decade used for model calibration and calibration variant representing different objective function) to the low-flow projection uncertainty shows that in basins with summer low flows climate scenarios contribute more than 75 % to the total projection uncertainty. In basins with a winter low-flow regime, the median contribution of climate scenario, decade and objective function is 29, 13 and 13 %, respectively. The implications of the uncertainties identified in this paper for water resource management are discussed.
Microbial water quality evaluations are essential for determining the vulnerability of subsurface drinking water sources to fecal pathogen intrusion. Rather than directly monitor waterborne pathogens ...using culture- or enumeration-based techniques, the potential of assessing bacterial community using 16S rRNA gene amplicon sequencing to support these evaluations was investigated. A framework for analyzing 16S rRNA gene amplicon sequencing results featuring negative-binomial generalized linear models is demonstrated, and applied to bacterial taxa sequences in purge water samples collected from a shallow, highly aerobic, unconfined aquifer. Bacterial taxa relevant as indicators of fecal source and surface connectivity were examined using this approach. Observed sequences of Escherichia, a genus suggestive of fecal source, were consistently detected but not confirmed by culture-based methods. On the other hand, episodic appearance of anaerobic taxa sequences in this highly aerobic environment, namely Clostridia and Bacteroides, warrants further investigation as potential indicators of fecal contamination. Betaproteobacteria sequences varied significantly on a seasonal basis, and therefore may be linked to understanding surface-water groundwater interactions at this site. However, sequences that are often encountered in surface water bodies (Cyanobacteria and Flavobacteriia) were notably absent or present at very low levels, suggesting that microbial transport from surface-derived sources may be rather limited. This work demonstrates the utility of 16S rRNA gene amplicon sequencing for contextualizing and complementing conventional microbial techniques, allowing for hypotheses about source and transport processes to be tested and refined.
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•Groundwater vulnerability to pathogen intrusion was informed by 16S rRNA sequencing.•Observed sequences suggestive of fecal source not confirmed by culture-based methods•Seasonality of Betaproteobacteria sequences may reflect surface connectivity.•Bacterial taxa reflecting episodic water quality changes and adequate purging identified•Sequences common to surface waters absent or present at low levels
Climate change and urbanisation in combination put great pressure on terrestrial and ocean ecosystems, vital for subsistence and wellbeing in both rural and urban areas of Pacific islands. Adaptation ...is urgently required. Nature-based solutions (NbS) offer great potential, with the region increasingly implementing NbS and linked approaches like ecosystem-based adaptation in response. This paper utilises three Pacific island nation case-studies, Kiribati, Samoa and Vanuatu, to review current NbS approaches to adapt and mitigate the converging resilience challenges of climate change and urbanisation. We look at associated government policies, current NbS experience, and offer insights into opportunities for future work with focus on urban areas. These three Pacific island case-studies showcase their rich cultural and biological diversity and, importantly, the role of traditional ecological knowledge in shaping localised, place-based, NbS for climate change adaptation and enhanced wellbeing. But gaps in knowledge, policy, and practice remain. There is great potential for a nature-based urban design agenda positioned within an urban ecosystems framework linked closely to Indigenous understandings of wellbeing.
Aquifers of coarse gravel are an important source for drinking water; however, coarse sediments are also particularly susceptible to the rapid and long‐range transport of pollutants through the ...vadose zone. Therefore, understanding the flow and solute transport in unsaturated gravel material is of utmost importance for the protection of drinking water resources. Experimental investigations of flow and transport processes are dependent on suitable sensor technology, but it is a considerable challenge to install soil moisture sensors in gravelly material. In this note, we developed a novel method to install soil moisture sensors with minimal disturbance in a large lysimeter with undisturbed gravelly sedimentary material, based on drilling access cavities in frozen material. We investigated whether it is possible to obtain reliable soil moisture measurements and found that the probes measured the flow dynamics pattern well but could not quantify realistic absolute water content values.
Shallow groundwater is one of the primary sources of fresh water, providing river base-flow and root-zone soil water between precipitation events. However, with urbanization and the increase in ...demand for water for irrigation, shallow groundwater bodies are being endangered. In the present study, 101 hydrographs of shallow groundwater monitoring wells from the watershed of the westernmost brackish lake in Europe were examined for the years 1997–2012 using a combination of dynamic factor and cluster analyses. The aims were (i) the determination of the main driving factors of the water table, (ii) the determination of the spatial distribution and importance of these factors, and (iii) the estimation of shallow groundwater levels using the obtained model. Results indicate that the dynamic factor models were capable of accurately estimating the hydrographs (avg. mean squared error = 0.29 for standardized water levels), meaning that the two driving factors identified (evapotranspiration and precipitation) describe most of the variances of the fluctuations in water level. Both meteorological parameters correlated with an obtained dynamic factor (r = −0.41 for evapotranspiration & r = 0.76 for precipitation). The strength of these effects displayed a spatial pattern, as did the factor loadings. On this basis, the monitoring wells could be objectively distinguished into two groups using hierarchical cluster analysis and verified by linear discriminant analysis in 98% of the cases. This grouping in turn was determined to be primarily related to the elevation and the geology of the area. It can be concluded that the application of the data analysis toolset suggested herein permits a more efficient, objective, and reproducible delineation of the primary driving factors of the shallow groundwater table in the area. Additionally, it represents an effective toolset for the forecasting of water table variations, a quality which, in the view of the likelihood of further climate change to come, is a distinctive advantage. The knowledge of these factors is crucial to a better understanding of the hydrogeological processes that characterize the water table and, thus, to developing a proper water resource management strategy for the area.
The
Laboratory Biological Activity Reaction Test
(LAB-BART) is an easy-to-use assay that utilizes metabolic capabilities to process an array of substrates to semi-quantitatively assess the presence ...of potentially adverse bacteria in a groundwater sample. Here, we evaluated LAB-BART for the assessment of groundwater samples obtained under real-life conditions from two riverbank filtration (RBF) sites in Austria. Samples were taken monthly for an overall experimental period of six months and analyzed following the manufacturer’s recommendations for measuring iron-related, sulfate-reducing, slime-forming and denitrifying bacteria. Additional measurements were done for analyzing chemical water composition, as well as bacterial community structure to evaluate the suitability of LAB-BART by identifying relevant bacteria. Results imply that while LAB-BART could not give detailed information on bacterial concentrations, it might be able to indicate hydrologically induced changes in biogeochemical processes in a subsurface system, thus allowing operators to determine an adequate response to a potential influx of undesired bacteria. Despite its limitations, LAB-BART might therefore be a valuable tool for monitoring purposes due to its ease of use, but more research is necessary to determine its accuracy in measuring bacterial activity.
•Pacific Ocean Cities at forefront of urbanisation and climate change pressures.•Ocean-centric, climate-responsive approaches essential for islands.•Nature-based solutions in islands show human ...wellbeing and biodiversity benefits.
‘Ocean Cities’ of the Pacific are where urban landscapes and seascapes meet, where built and natural environments interface, and where human behaviour and urban development have profound impacts on both terrestrial and marine ecosystems. Ocean Cities are at the forefront of climate change consequences, urbanisation challenges, and other development pressures. This article discusses the potential for nature-based solutions (NbS), including those focused on ecosystem services, in Pacific Small Island Developing States (SIDS) as a response to climate change, population growth, and urbanisation. Attention is directed to identifying the benefits of NbS and case-studies from Pacific SIDS, and if not available regionally, further afield. The article provides focus on possible barriers to implementation of NbS in a Pacific SIDS context and potential policy responses to these. Conclusions are threefold: (i) addressing interlinked ecological, climate, and human wellbeing issues in an integrated, ocean-focused and climate-responsive manner is vital for sustainable development in island systems; (ii) NbS can provide significant human wellbeing and biodiversity benefits in this context; and (iii) Pacific Ocean Cities, with a significant body of relevant traditional knowledge and emerging NbS experience, can inform global understanding of how to address converging urbanisation and climate change issues in Ocean Cities.
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