Groundwater-dependent Ecosystems Research Articles

A comparative evaluation of arid inflow-dependent vegetation maps derived from LANDSAT top-of-atmosphere and surface reflectances

ABSTRACTIn remote sensing, it is commonly accepted that land remote-sensing satellite (LANDSAT) top-of-atmosphere (TOA) reflectance is less accurate than atmospheric correction (AC) reflectance, as the former is not calibrated for possible modifications in the electromagnetic radiation signals due to atmospheric scattering and absorption. This article investigates whether LANDSAT data calibrated for TOA reflectance are an appropriate information source for delineating inflow-dependent vegetation (IDV) in regions with an arid and desert climate, such as the Pilbara region in Western Australia. Knowledge of where IDVs are in the landscape underpins planning their protection and define the baseline for their monitoring when water resource management options are considered. The appropriateness of TOA calibration for the delineation of IDV in the Pilbara was assessed through its comparison with IDV maps derived from AC reflectance. Both radiometric calibration methods (TOA and AC) were applied to a multi-date LANDSAT 5 TM (Thematic Mapper) dataset of 10 images acquired in 2009 and 2010. Two methods based on the application of remote-sensing techniques to identify the extent of temporally invariant vegetation were applied for IDV delineation in the study area. The first method, groundwater-dependent ecosystems mapping (GEM), employs a two-date normalized difference vegetation index (NDVI) dataset for identifying ‘no-change’ clusters of land cover and detecting those related to IDV. The second method applies principal component analysis (PCA) to a multi-date NDVI dataset. The first principal component (PC1) typically contains features that remain unchanged over time. This includes vegetation with continuous or frequent access to surface and/or groundwater, such as IDV. To delineate the extent of IDV, a thresholding technique was further employed. Spatial similarity between IDV maps produced from TOA and AC reflectance was quantitatively evaluated by the Kappa coefficient. The results showed that TOA and AC IDV maps are in ‘almost perfect’ agreement with the Kappa values above 0.83. This suggests that TOA reflectance is equally appropriate to AC reflectance for mapping in arid and desert climate such as in Pilbara. When the GEM- and PCA-based methods are applied in other study areas with arid or desert climate, the accuracy of the delineated IDV extent may vary. Therefore, the results need to be validated using ground-truth information about known IDV occurrences in the area of interest.

Economic valuation of groundwater protection using a groundwater quality ladder based on chemical threshold levels

Improving groundwater quality is expected to yield direct use benefits to society (e.g. clean and safe drinking water) and groundwater dependent ecosystems. Ten years after the adoption of the European Groundwater Directive (GWD), policymaker and public understanding of the societal value of groundwater protection is still rather limited. This is partly due to the invisible and intangible nature of groundwater resources and the sheer lack of valuation studies. This study contributes to the limited number of groundwater valuation studies in Europe by estimating the public benefits from improved groundwater quality in the Aveiro Quaternary Aquifer (AQA) in Portugal. This is the first and only economic valuation study of groundwater in Portugal. In order to communicate the various benefits provided by groundwater resources in easy understandable terms to lay people, and to assess public perception and willingness to pay (WTP) for groundwater protection, a groundwater quality ladder was developed based on the threshold values proposed in the GWD. The ladder reflects the different use and non-use values of groundwater quality improvements and accounts for natural background levels of chemicals in groundwater. The large-scale survey targets a representative sample of residents in the AQA. Split samples are used to assess the impact of framing groundwater protection in a broader regional water resources management context, giving part of the sample furthermore time to think about their WTP for the different groundwater threshold levels. Although use values dominate public WTP for the different groundwater threshold values, substantial non-use values are also found. Public WTP is considerable, varying between 20 and 30% over and above the current water bill residents pay for safe drinking water quality and natural background levels, respectively. Giving respondents time to think and framing groundwater protection as part of the improvement of all water resources in the region results in a more conservative WTP estimate. Public WTP is higher for better informed private well owners in rural areas. Aggregated across the entire aquifer the estimated total economic value is 1.5 million euros annually for safe drinking water quality and 3.5 million euros annually for groundwater containing natural background levels only.

Revisiting groundwater overdraft based on the experience of the Mancha Occidental Aquifer, Spain

Aquifers provide a reliable freshwater source in arid and semiarid regions, where droughts are common and irrigated crops present significant water requirements, so intensive pumping is generally needed. Over-extraction leads to dropping water tables, which in turn threatens the survival of groundwater-dependent ecosystems and water supplies. This calls for strategies to channel hydrological, environmental, agricultural, political and social change. Based on the experience of the Mancha Occidental aquifer, Spain, this paper explores some of the complexities of managing groundwater, dealing with the long-term changes that intensive groundwater use has generated in the region. The Mancha experience shows how environmental conservation may drive social and economic change at the regional scale for periods spanning several decades. What makes this case study unique, however, is the combination of social and environmental conflicts, most of which stem from the prevalence of illegal water use, and their detrimental effect on Ramsar wetlands. The situation exposed a paradox, namely that subsidies for farmers to cut down on water use were actually detrimental to the welfare of groundwater-dependent ecosystems. The unexpected (and timely) occurrence of extreme rainfall events in recent times, after 40 years of ineffective management measures and sustained environmental degradation, enabled the aquifer and its associated wetlands to recover spectacularly to a near-pristine condition. As groundwater-dependent wetlands are highly sensitive ecosystems, it is concluded that it is up to society to decide how much environmental damage can be tolerated in exchange for the social and economic benefits of groundwater-based development.

The Compatibility of Geothermal Power Plants with Groundwater Dependent Ecosystems: The Case of the Cesine Wetland (Southern Italy)

The Cesine Wetland, located along the Adriatic coast, was recognized as a Wetland of International Interest and a National Natural Park. Managed by the “World Wide Fund for nature” (WWF), it is considered a groundwater dependent ecosystem which is affected by seawater intrusion. The site was selected to test the environmental compatibility of a low-enthalpy geothermal power plant (closed loop) operating in the aquifer saturated portion with purpose to improving the visitor centre. For this purpose, the long-lasting thermal impact on groundwater was assessed using a multi-methodological approach. The complex aquifer system was carefully studied with geological, hydrogeological and geochemical surveys, including chemical and isotopic laboratory analyses of surface water, groundwater and seawater. The isotopes δ18O, δD, δ11B, and 3H were useful to clarify the recharge contribution, the water mixing and the water age. All information was used to improve the conceptualization of the water system, including aquifers and the boundary conditions for a density driven numerical groundwater model. The purpose was to forecast anthropogenic thermal groundwater variations up to 10 years of plant working before the plant realization and to validate the solution after some working years. All results show the environmental compatibility notwithstanding the peculiar ecological environment.

Update of the information guidelines to improve scientific information provided to the Independent Expert Scientific Committee on Coal Seam Gas and Large Coal Mining Development

The Independent Expert Scientific Committee on Coal Seam Gas and Large Coal Mining Development (IESC) provides scientific advice to decision makers on the impact that coal resource development may have on Australia’s water resources. In particular, advice is provided on development proposals that have been submitted to the Australian Government and relevant state governments in the form of environmental impact statements (EISs). The Information Guidelines developed by the IESC outline the information considered necessary to enable the IESC to provide robust scientific advice to government regulators on the water-related impacts of coal resource development proposals. Proponents preparing EISs are strongly encouraged to consult the Information Guidelines before developing and submitting a proposal. The Information Guidelines have been updated for the first time since 2015 and will be presented. The update includes important and more detailed information about what types and the level of information that should be included in EISs. In addition a series of ‘explanatory notes’ have been developed which provide practical examples of how information should be presented in an EIS. The first two explanatory notes relate to uncertainty analysis in numerical groundwater modelling and how to undertake comprehensive assessments and manage impacts to groundwater dependent ecosystems. Two additional explanatory notes will be released for use later in 2018. The updated Information Guidelines are a continuing step towards improving the robustness of information provided to the IESC.

Winter Rain versus Snow in Headwater Catchments: Responses of an Unconfined Pumice Aquifer, South-Central Oregon, USA

Winter precipitation in two headwaters catchments (elevation ~1600 m) in the rain shadow of the Cascades volcanic arc in south-central Oregon normally falls as snow. However, in water year 2015, winter precipitation fell mainly as rain. An eight year study of the unconfined pumice aquifer allowed inter-annual comparison of groundwater recharge during the freshet and discharge during the growing season. During these water years precipitation ranged from 67% (WY2014) to 132% (WY2017) of the 30 year average, and included the rain dominated winter of WY2015 when precipitation during the water year was 98% of the 30 year average. Change in storage in the pumice aquifer was estimated from thickness of the pumice deposit and depth to water table from the ground surface. Measurements were made where 1) the pumice aquifer was exposed at the surface; 2) where the aquifer was partially eroded and overlain by either alluvium or lacustrine glassy silt to fine sand; 3) fens where the partially eroded aquifer was overlain by peat; and 4) monitoring wells drilled through the pumice aquifer into bedrock. In all settings, groundwater storage in the pumice aquifer following the rain-dominated winter of WY2015 was similar or less than storage following the drought of WY2014 when winter precipitation fell as snow. Storage at the end of WY2014 and WY2015 was the least observed in the eight year study. Winter-time rain during WY2015 produced runoff rather than storage in snow pack. Runoff conveyed from the catchments by flow in stream reaches normally dry from late summer through the winter months. Rain-dominated winter precipitation stresses the perched pumice aquifer. Winter storms starting as rain and turning late to snow and ground-freezing temperatures lead to runoff during the next rain-dominated precipitation event. These patterns produced stream flow in channels that are commonly dry during the winter, reduced near-surface groundwater storage in the pumice aquifer, muted springtime freshet, and stressing of groundwater-dependent ecosystems, forage in meadows, and forest health.

Ammonium natural attenuation in complex hydrogeological settings: insights from a multi-isotope approach

A full methodology including a multi-isotopic approach coupled with depth-dependent groundwater sampling is here reported to investigate the occurrence of ammonium natural attenuation. Examples from three hydrogeological settings, representative of different environmental issues in relation to nitrate and ammonium pollution are here reported: a septic system plume (SSP), where the discharging effluent composition into a shallow aquifer is dominantly ammonium-based; a Groundwater Dependent Ecosystem (GDE), where river waters are impacted by upwelling of anthropogenic and natural ammonium negatively affecting the ecosystem’s functionality, and an alluvial coastal aquifer (ACA) affected by abnormal natural ammonium concentrations along with a high content of other undesired compounds. Several sampling methodologies were applied for depth-dependent groundwater sampling such as multi-level nested wells, straddle packers system, and common long screen wells. Such detailed sampling techniques were coupled with a multi-isotopic approach. Environmental isotopes (δ18O and δD in H2O) were used to gain insights into the hydrogeological flow system while other stable isotopes δ15NNH4, δ15NNO3, δ18ONO3 were purposefully applied for the identification of N compounds’ source(s), fate and processes. In addition, δ34SSO4, δ18OSO4, and δ13CDIC were proposed as tools for understanding the potential attenuation processes in relation to the other biogeochemical cycles. Tritium data was also applied for recharge rate and groundwater residence time estimation. The adopted approach helped reaching site-specific insights into the hydrogeological and geochemical conceptual models. In SSP, the isotopic evidence of anammox occurrence, together with denitrification and nitrification processes, result to be responsible of the 60-80% of the total N removal at the distal portion of the plume; in GDE, ammonium and nitrate, coming mainly from agricultural practices, affect the deep and the shallow flow systems. Ammonium results to be locally attenuated by dilution and nitrification. In ACA, the major ammonium pool derives from the low-lying aquitard as a biogenic source while anthropogenic minor inputs (NH4+ and NO3 -) from the shallow circulation in the aquifer were also identified. NH4+ resulted attenuated by transport processes and partial nitrification processes. Moreover, by the use of a multiisotope approach sound evidence of the anaerobic oxidation of methane coupled with SO42- reduction has been arisen. The overview provided by the proposed case studies put emphasis on the importance of the identification of reliable conceptual models which cluster physical patterns (e.g. groundwater flow) together with chemical and isotopic data, representing a fundamental step in the integration of the groundwater and the nitrogen cycles, thereby of high concern for sustainable water management and best practices.

Groundwater vulnerability mapping for a sub-catchment of the Rio La Venta watershed, Chiapas, Mexico

Karst systems are particularly vulnerable to overexploitation and pollution due to their high hydraulic conductivity and points of rapid infiltration that allow quick influx of runoff and pollutants into the aquifer. The sustainability of non-contaminated groundwater in these systems is imperative for both humans and groundwater-dependent ecosystems. An important practice in managing groundwater sustainability involves assessing aquifer vulnerability. This study created the first groundwater vulnerability map (GVM) for a sub-catchment of the Rio La Venta watershed in Chiapas, Mexico, using an adaptation of the hazard–pathway–target method. This project also conducted the first tracer study in the Rio la Venta watershed to establish connectivity between the catchment and the Rio La Venta Canyon. Finally, this study evaluated the results of the GVM through a sensitivity analysis. Results of the GVM clearly demarcate areas of very high, high, moderate, and low vulnerability within the study area most of which being classified as low vulnerability. The zones of high vulnerability were successfully validated through two dye tracer tests that measured rapid groundwater flow velocities. With the limited resources available to land managers in this area, a problem common in many developing countries, tools that quickly and inexpensively highlight areas that require special protection to help maintain or improve water quality in their watersheds have great utility. Conveying this information to land managers and policymakers can lead to potential changes in current land use practices and allow for the reallocation of resources in support of reducing future negative human–landscape interactions.

Evaluating the risk of groundwater drought in groundwater-dependent ecosystems in the central part of the Vistula River Valley, Poland

The objective of this study was to seek better insight into the natural factors that may contribute to hydrogeological drought in shallow hydrogeological ecosystems that exhibit significant seasonal and multiannual groundwater-level dynamics. With this aim, we monitored groundwater levels in two groundwater-dependent ecosystems (GDEs) situated close together in the central part of the Vistula Valley regularly at 14-day intervals over a long-term period (1999–2013), using a monitoring network of 17 piezometers of the monitoring network (recording about 6600 observations overall). The piezometers were situated such that they were not under the direct influence of anthropopressure, thus allowing the results to be interpreted as the influence of natural factors on the quantitative state of GDEs. We found that the groundwater level changes over the study period can be classified as exhibiting hydroperiods of the periodic type, with a typical seasonal-level fluctuation pattern, without any distinct long-term trend. Statistical analysis showed that hydrogeological droughts, characteristic of the summer months, occur only during years when the lowest groundwater levels were observed. Shallow hydrogeological droughts occur periodically, from summer to spring, and the average duration of shallow droughts was 8 weeks. Overall, this study illustrates how analysis of groundwater-level fluctuations in GDEs on multiannual and seasonal scales, determining the fluctuation trends and the values of critical levels, provides better understanding of the risk of groundwater drought hazard and occurrence. Assessment of the natural range of groundwater-level fluctuations can then assist in effecting better local water resource management and may aid agricultural organizations and development/planning authorities to improve their understanding of sustainable groundwater resource management.

Variations in microcrustacean (Crustacea: Cladocera, Copepoda) assemblages from selected groundwater-dependent ecosystems in the greater Luzon and Mindoro Island faunal regions (Philippines): insights to tropical groundwater ecology

In the Philippines, the ecology of microcrustaceans from groundwaters and their dependent ecosystems remain poorly understood, yet knowledge about this group can elucidate patterns in groundwater biodiversity to develop sound conservation policies. In this study, microcrustaceans were studied by collecting samples from 102 groundwater-dependent ecosystems, including 51 artesian wells, 23 caves, 14 springs, and 14 piped groundwater pumps during the dry (Nov 2014 to Apr 2015) and wet (May–Oct 2015) seasons. Results indicate the presence of 21 species from Cladocera and Copepoda, including 2 obligate stygobionts and 19 species consist with surface water and facultative stygobiotic taxa. Significant differences in microcrustacean assemblages were noted among types of groundwater-dependent ecosystems (P < 0.05), wherein wells and caves harbored more abundant assemblages with higher total species richness; however, no significant variations were observed between seasons (P > 0.05). Furthermore, principle component analysis revealed that sampling sites were highly characterized by altitude, specific conductivity, and total water hardness. Microcrustacean assemblages in sampled sites were highly dominated by the influence of temperature, dissolved oxygen, and altitude. Species rarefaction analysis revealed low species richness in sampled sites within the region, supporting the existing notion that temperate groundwater-dependent ecosystems were more diverse, and faunal composition in terms of ecological groups is extremely different in tropical and temperate settings.

Anthropogenic habitat disturbance induces a major biodiversity change in habitat specialist bryophytes of boreal springs

Land-use is a major driver of global biodiversity loss. Despite much evidence of land-use impacts on freshwater biodiversity, long-term changes to groundwater-dependent ecosystems, and their post-disturbance recovery, remain largely unknown. We examined long-term changes of bryophyte communities in 34 boreal springs from 1987 to 2015. In 1987, all the study springs were in near-pristine condition, but 29 of them were disturbed by peatland drainage in the late 1980s and early 1990s. Five sites retained their natural status throughout the study and were used as reference sites. We aimed to assess whether bryophyte vegetation, particularly spring specialist bryophytes, showed gradual recovery toward near-pristine conditions or whether the drainage-induced habitat degradation had caused delayed extinctions of specialists, leading to dominance by generalist taxa. Bryophyte diversity showed no signs of recovery about 20years since the initial disturbance. In disturbed springs, the abundance of specialists first decreased, then remained relatively stable. Specialist richness decreased steadily and their community composition shifted gradually from the pre-disturbance state. Abundance of habitat generalists did not change but generalist richness also decreased with a time lag. At the same time, both groups remained unaltered in undisturbed springs. We conclude that without restoration measures that improve groundwater hydrology the self-recovery potential of springs is very low. As little is currently known about the effectiveness of spring restoration in halting spring biodiversity loss, the safest management strategy is to refrain from land use within broad buffers around springs.

Impacts of predicted climate change on groundwater flow systems: Can wetlands disappear due to recharge reduction?

Climate change can directly influence groundwater systems through modification of recharge. Affecting not only groundwater levels and flow dynamics, climate change can also modify the fragmentation and hierarchy of groundwater flow systems. In this study, the influence of climate change – impacted recharge on groundwater levels and on inter-connected groundwater flow patterns is evaluated. Special emphasis is placed on how flow system hierarchy may change, to examine possible consequences on groundwater-related shallow surface water bodies and on groundwater – surface water interaction. As a test site with no significant anthropogenic impacts, the Tihany Peninsula in Hungary was an ideal area for the study. We address the following issues: i) How might a groundwater system, including groundwater-surface water interaction, be modified by predicted climate change?, ii) Given the variable groundwater levels and flow patterns, how will the water levels and fluxes be impacted around surface water bodies?, and iii) How sensitive are groundwater-related wetlands to these changes, and will they be maintained or will they eventually disappear? In order to answer these questions, two-dimensional transient numerical simulations were performed based on site-specific measurements and climatic prediction at the Tihany Peninsula. Results show that future climate trends can cause dynamic evolution and dissipation of transient groundwater flow systems, and the characteristic flow system hierarchy can change from nested flow systems to a set of single flow cells. Preservation of associated groundwater-dependent ecosystems would be challenging under these conditions since long-term climate change could potentially have serious consequences, including wetland disappearance. Understanding these transient processes in two-dimensions can also help to set-up three-dimensional site-specific models.

Protection of groundwater dependent ecosystems in Canterbury, New Zealand: the Targeted Stream Augmentation Project

In Canterbury, New Zealand, native aquatic species habitat has significantly declined over the last century due primarily to land use change and climatic influences. The Canterbury Water Management Strategy (CWMS) aims to improve such habitat while also meeting other economic, environmental, social and cultural objectives. The focus of this paper will be on the Targeted Stream Augmentation (TSA) Project in the Selwyn-Waihora Zone in Canterbury. The semi-arid climate, significant demand for irrigation water and the up-gradient aquifer pressure provided by a coastal lake provide significant aquifer management challenges in this zone. In response to these challenges the local CWMS committee recommended that managed aquifer recharge trials to improve groundwater dependent ecosystems start in a highly targeted manner before gradually increasing the distance from recharge site to the target spring/s. A highly targeted pilot trial has shown the flow, temperature and nutrient concentration benefits for the target surface ecosystem. The implementation of two larger scale concepts combining surface and groundwater ecosystem benefits is now progressing. Lessons learned to date include the importance of keeping engagement processes ahead of technical assessments, and the benefits of high level scoping assessments before committing to detailed investigations and pilot projects.

Impact of Changes in Groundwater Extractions and Climate Change on Groundwater-Dependent Ecosystems in a Complex Hydrogeological Setting

Climate change and other future developments can influence the availability of groundwater resources for drinking water. The uncertainty of the projected impact is a challenge given the urgency to decide on adaptation measures to secure the drinking water supply. Improved understanding on how climate change affects the groundwater system is necessary to develop adaptation strategies. AZURE is used, a detailed, well-calibrated hydrological model to study the projected impact of climate change scenarios on the large Veluwe aquifer in the Netherlands. The Veluwe area is an important source of drinking water. However, some existing groundwater extractions in the area affect nearby groundwater-dependent ecosystems. Redistribution of the licensed extraction volumes of these sites is considered to reduce the impact on these ecosystems. The projected impact of climate change and redistribution to groundwater levels is studied. The research shows that in a slowly responding large aquifer the projected climate change may cause rising groundwater levels despite the projected increase in summer dryness. The results indicate that this impact may exceed the impact of redistribution of extraction volumes. In addition, it is shown that the combined effect strongly depends on local conditions, thus highlighting the need for high-resolution modelling.

Groundwater nitrate response to sustainable nitrogen management

Throughout the world, nitrogen (N) losses from intensive agricultural production may end up as undesirably high concentrations of nitrate in groundwater with a long-term impact on groundwater quality. This has human and environmental health consequences, due to the use of groundwater as a drinking water resource, and causes eutrophication of groundwater-dependent ecosystems such as wetlands, rivers and near-coastal areas. At national scale, the measured nitrate concentrations and trends in Danish oxic groundwater in the last 70 years correlate well with the annual agricultural N surpluses. We also show that the N use efficiency of agriculture is related to the groundwater nitrate concentrations. We demonstrate an inverted U-shape of annual nitrate concentrations as a function of economic growth from 1948 to 2014. Our analyses evidence a clear trend of a reversal at the beginning of the 1980s towards a more sustainable agricultural N management. This appears to be primarily driven by societal demand for groundwater protection linked to economic prosperity and an increased environmental awareness. However, the environmental and human health thresholds are still exceeded in many locations. Groundwater protection is of fundamental global importance, and this calls for further development of environmentally and economically sustainable N management in agriculture worldwide.

Revealing the economic value of managed aquifer recharge: Evidence from a contingent valuation study inItaly

AbstractManaged aquifer recharge [MAR) is a promising water management tool toward restoring groundwater balance and securing groundwater ecosystem services (i.e., water for drinking, industrial or irrigation use, control of land subsidence, maintenance of environmental flows to groundwater dependent ecosystems, etc.). Obviously, MAR projects can improve the quality of lives of the people by several ways. Thus, from a social perspective, the benefits of MAR cannot and should not be based only on market revenues or costs. Although the value of groundwater, from a social perspective, has been a subject of socio‐economic research, literature on the value of MARper seis very limited. This paper, focusing on Italy which is a country with extensive utilization of MAR, aims to estimate the economic value of MAR and makes a first step toward filling this gap in the literature. For this purpose, the Contingent Valuation method was implemented to provide a monetary estimate and to explore the factors influencing people's attitude and willingness to pay for MAR. The results show that society holds not only use but also significant nonuse values, which are a part of the total economic value (TEV) of groundwater according to related research efforts. To this end, MAR valuation highlights its social importance for groundwater conservation and provides a solid basis for incorporating its nonmarket benefits into groundwater management policies and assessments.

Integrated science informs forest and water allocation policies in the South East of Australia

Groundwater-dependent ecosystems are particularly vulnerable to groundwater decline. The South East of South Australia has experienced considerable hydrological change due to drainage, clearance of native vegetation, irrigated agriculture, and forestry. Recent hardwood plantings in the Limestone Coast Prescribed Wells Area (PWA) have increased considerably since 2000, coincident with groundwater decline; however, the introduction of hardwood plantations coincided with a period of lower than average rainfall. Given the economic implications of modifying water allocation policy based on apparent anthropogenic causes, establishing the contributions to the observed declines in groundwater level was necessary. The water balance shows a net gain in water across the entire Lower Limestone Coast Prescribed Wells Area, yet sites with forestry land use show the water table has been declining at a rate up to 0.7 m yr−1 since 2004, whereas no long-term change has occurred in the water table depth at adjacent pasture sites. Forested areas have 4050 wetlands at risk with groundwater decline >0.3 m yr−1, covering a total wetland area of of 212 km2. A series of 15 policy scenarios were simulated using a groundwater flow model to examine how climate, land use, and particularly forestry would impact groundwater, with an imperative to enact policy to protect remaining wetlands. Water allocation policy accounted for groundwater extraction for irrigated agriculture, but other activities, such as forestry, were not considered in water allocation even though they were found to be a major water user. Following this study, the South Australian Government amended its Natural Resources Management act to stipulate that forestry must have a water licence and a water allocation to account for water used by the forest.

Production of Hydrogen Peroxide in Groundwater at Rifle, Colorado

The commonly held assumption that photodependent processes dominate H2O2 production in natural waters has been recently questioned. Here, we present evidence for the unrecognized and light-independent generation of H2O2 in groundwater of an alluvial aquifer adjacent to the Colorado River near Rifle, CO. In situ detection using a sensitive chemiluminescent method suggests H2O2 concentrations ranging from lower than the detection limit (<1 nM) to 54 nM along the vertical profiles obtained at various locations across the aquifer. Our results also suggest dark formation of H2O2 is more likely to occur in transitional redox environments where reduced elements (e.g., reduced metals and NOM) meet oxygen, such as oxic-anoxic interfaces. A simplified kinetic model involving interactions among iron, reduced NOM, and oxygen was able to reproduce roughly many, but not all, of the features in our detected H2O2 profiles, and therefore there are other minor biological and/or chemical controls on H2O2 steady-state concentrations in such aquifer. Because of its transient nature, the widespread presence of H2O2 in groundwater suggests the existence of a balance between H2O2 sources and sinks, which potentially involves a cascade of various biogeochemically important processes that could have significant impacts on metal/nutrient cycling in groundwater-dependent ecosystems, such as wetlands and springs. More importantly, our results demonstrate that reactive oxygen species are not only widespread in oceanic and atmospheric systems but also in the subsurface domain, possibly the least understood component of biogeochemical cycles.

Adapting to the effects of climate change on natural resources in the Blue Mountains, USA

National forests in the Blue Mountains (USA) region have developed adaptation options that address effects identified in a recent climate change vulnerability assessment. Adaptation strategies (general, overarching) and adaptation tactics (specific, on-the-ground) were elicited from resource specialists and stakeholders through a workshop process. For water supply and infrastructure, primary adaptation strategies restore hydrologic function of watersheds, connect floodplains, support groundwater-dependent ecosystems, maximize valley storage, and reduce fire hazard. For fisheries, strategies maintain or restore natural flow regimes and thermal conditions, improve water conservation, decrease fragmentation of stream networks, and develop geospatial data on stream temperature and geologic hazards. For upland vegetation, disturbance-focused strategies reduce severity and patch size of disturbances, protect refugia, increase resilience of native vegetation by reducing non-climate stressors, protect genotypic and phenotypic diversity, and focus on functional systems (not just species). For special habitats (riparian areas, wetlands, groundwater-dependent ecosystems), strategies restore or maintain natural flow regimes, maintain appropriate plant densities, improve soil health and streambank stability, and reduce non-climate stressors. Prominent interactions of resource effects makes coordination critical for implementation and effectiveness of adaptation tactics and restoration projects in the Blue Mountains.

Evaluation of the sources of nitrogen compounds and their influence on the biological communities in the hyporheic zone of the Sagittario River, Italy: an isotopic and biological approac

In groundwater-dependent ecosystems (GDEs) a significant contribution of nitrogen contamination of the surface waters arises from groundwater input by shallow and deep flow systems. In general, nitrogen surface-groundwater exchanges and processes at the hyporheic scale are difficult to monitor. In order to have a better understanding about these interactions, it is proposed to use stable isotopes (15N-NO3-, 18O-NO3-, 15N-NH4+) as environmental tracers to identify the sources and fate of the nitrogen compounds in groundwater in the Sagittario River basin, central Italy. The detrimental effect of the groundwater ammonium on the meiofaunal organisms is also evaluated in the hyporheic zone, where N-NH4+ concentrations reach a maximum value of 0.6 mg L-1. The main source of the nitrogen contamination originates from agricultural and urban activities at the catchment scale. The nitrogen compounds reach the gaining stretches of the hyporheic zone along the streambed as nitrate associated to a shallow flow system and ammonium related to a deep flow system. δ15N data demonstrate that sewage and fertilizers including manure are the main sources of NO3- and NH4+, the latter being the major pollutant in the study area. δ18O-NO3- data are consistent with the nitrification of ammonium to nitrate, along with the contribution from inorganic fertilizers. Furthermore, δ15N-NO3- and δ18O-NO3- data reveal that denitrification does not play any role on nitrate attenuation in the shallow aquifer and near the discharge areas to the river. The meiofaunal communities, represented by the Crustacea Copepoda selected as the target group, were shown to be sensitive to the high concentration of ammonium found at several hyporheic sites. The statistical analyses indicated a significant reduction of species abundance in the sites polluted by N-NH4+ concentrations > 0.0653 mg L-1.