Shalsi, SarahOrdens, Carlos M.Curtis, AllanSimmons, Craig T....
15页
查看更多>>摘要：Resource-user participation in decision-making, through local collective action, likely contributes to effective groundwater management and protection. Despite efforts to construct generalized theoretical frameworks explaining factors influencing successful collective action in groundwater management, this is a highly complex process that remains challenging. This paper analyzes factors facilitating and impeding collective action in groundwater management, using the rare and successful collective-action example of the Angas Bremer irrigation district (South Australia). Drawing on data gathered through semi-structured interviews this paper further explores the context under which collective action arose and changed over time. The findings show a dynamic transient interaction between the following factors responsible for the rise and fall of collective action: (i) perceived crisis, (ii) small, homogenous community (iii) strong leadership from respected community members, (iv) shared norms and values, (v) shared goals, and (vi) trustworthy two-way relationship between resource users and formal institution. Although it is difficult to generalize from one case study, collective action and groundwater management are highly contextual. These findings are useful (i) for other communities with similar characteristics, (ii) to explore conditions for achieving successful groundwater governance including efficient and effective reforms, (iii) to highlight the importance of participatory management processes, (iv) to help government agencies understand what motivates communities to engage in collective action and how that leads to successful groundwater co-management, and (v) to expand on a very small body of literature documenting stakeholders narratives on collective action and groundwater management.
查看更多>>摘要：Low impact development (LID) facilities have been regarded to have important regulatory effects on urban evapotranspiration (ET). However, due to the influences of heterogeneity of underlying surfaces or facilities, solar radiation, building shading and rainfall conditions, the ET variations in outdoor space of urban buildings (OSUB) with various LID facilities are complex and have not been reported. In this paper, a three-temperature model (so called 3T model) combining with a portable thermal infrared imaging sensor was used to in-situ measure the ET rates of different LID facilities and traditional underlying surfaces of an OSUB in 2019 in Shenzhen, China. Specifically, the seasonal, daily and diurnal variations of ET in the OSUB and their influencing factors were investigated. The results indicate that (1) the LID facilities have higher ET rates than the traditional surfaces in wet seasons; the ET rates of bioretention (BR-H), vegetated swale (VS-Z) and permeable concrete pavement (PCP) are 38%, 18% and 250% higher than those of traditional garden (TG-H), lawn (TL-Z) and impermeable brick pavement (IBP), respectively, in this study; (2) the diurnal variation of ET is greatly affected by solar radiation intensity, building shadow and moisture inside the LID facilities; and the ET increase by LID is higher in the OSUB with higher solar radiation and no shadow; (3) vegetated LID facilities (e.g., BR-H and VS-Z) can maintain at a relatively high ET rate for a longer period after rain than the non-vegetated LID facilities (e.g., PCP), indicating a stronger ability to increase urban ET; (4) when the proportion of LID in OSUBs increases from 0% to 50% and 100%, the ET rate of OSUBs increases by 28% and 51% respectively, and the annual ET of built-up areas in Shenzhen increases by 6.58 mm and 11.41 mm respectively. The effects of soil media, vegetative cover, LID facility structure, local climate and building shadow on the ET of OSUBs should be considered for extrapolating the site-scale study to urban or catchment scale.
查看更多>>摘要：Cable bacteria have been discovered in various marine and freshwater habitats, and their unique metabolism named electrogenic sulfide oxidation (e-SOx) is of great ecological significance to aquatic ecosystems. However, the environmental factors that determining the dynamics and abundance of cable bacteria in freshwater sediments are not well understood. In this study, we examined the activity and growth of cable bacteria in response to the change of oxygen availability in freshwater sediments. The metabolic activity of cable bacteria was quantified by microsensor profiling, while their abundance was determined by fluorescence in situ hybridization and 16S rRNA gene sequencing. The increase of oxygen availability greatly promoted the metabolic activity and proliferation of cable bacteria, as reflected by a higher rate of e-SOx and a larger population size. As affected by the change of sulfide availability and oxygen demand with the proliferation of cable bacteria, these promoting effects were more pronounced at later development stage. Moreover, the elevation of oxygen availability drove the downwards growth of cable bacteria and the increased inventories of dissolved sulfate in deeper sediment layers, which may expand the influences of cable bacteria on sediment biogeochemical cycling on the vertical scale. Our results contribute to further understanding of the correlations between oxygen availability and growth dynamics of cable bacteria in natural environments.
查看更多>>摘要：Soil moisture is a crucial component of the forest ecosystem because it primarily controls vegetation growth. However, the potential for predicting the subsurface from the surface soil moisture through (de)coupling in boreal larch forest (Larix gmenilii) in China has rarely been investigated. In the present study, the regression and residual as well as cross-correlation analyses were used to evaluate the relationship between the surface (5 cm) and subsurface (10, 20, and 40 cm as well as the profile soil moisture) soil moisture in the Larix gmenilii forest. The applicability of the exponential filter (ExpF) and cumulative distribution function matching (CDF) methods for estimating the subsurface using the surface soil moisture in the study area and the impacts of (de)coupling on the simulation accuracy were assessed. Our results shown that the coupling between surface and subsurface soil moisture decreased with soil depth increasing and decoupling is dominant in the range varying between 0.11 and 0.22 cm(3)cm(-3). The CDF method exhibits superiority for estimating the subsurface soil moisture relative to the ExpF method in the study area. Furthermore, the surface soil moisture values in the coupling range capture the dynamics of the subsurface soil moisture, while decoupling significantly reduces the accuracy of simulating the subsurface soil moisture. Thus, we propose an approach involving the reconstruction of the coupling time series associated with the (de)coupling, which improves the accuracy of the subsurface soil moisture simulation, particularly at depth, where the coupling is weak. Thus, the (de)coupling effect should henceforth be incorporated in the future subsurface soil moisture simulation studies and is helpful to understand the hydrological process of soil, improve regional models and the associated parameters.
查看更多>>摘要：Riparian corridors serve as buffer zones between land and water, thereby supporting essential ecosystem services. Though riparian zones occupy around 1% of land area in midwestern USA watersheds, their management has significant societal consequences on downstream ecosystem services, such as water quantity and quality. The management of riparian zones in the Minnesota River Basin (MRB) needs a comprehensive decision support framework (DSF) to guide conservationists to invest resources efficiently. This study attempts to classify riparian zones based on three classes: stream features, riparian characteristics, and riparian functions to suggest suitable Best Management Practices (BMPs). We developed a comprehensive hybrid decision support framework (DSF) by integrating fuzzy analytical hierarchy process (AHP) and fuzzy inference system (FIS) to propose riparian BMPs based on the physical characteristics of stream, riparian zone, and desired riparian functions. The DSF accommodates the uncertainty associated with the stakeholder's perceptions towards the riparian zone classes while also accounting for continuous variation in riparian dynamics. The advantage of a hybrid model is its ability to allow the stakeholders to prioritize critical criteria belonging to the classes to ensure that they have maximum impact on the riparian BMPs proposed by the model. We have demonstrated the model using three Minnesota River tributaries at the Hydrologic Unit Code (HUC)-8, HUC-10, HUC-12 scales. Results show that BMPs such as riparian revegetation, buffer strips, wetland management, the addition of woody debris, and an increase in tree cover obtained the highest scores and occupied 35%, 25%, 15%, 10%, and 10% of the observed sites, respectively.
查看更多>>摘要：The Gravity Recovery and Climate Experiment (GRACE) provided an entirely new way to measure mass changes on the Earth at unprecedented accuracy and resolution. However, the delayed launch of the GRACE Follow On (FO) mission led to an approximately 1-year gap between GRACE and GRACE-FO data, breaking the continuity of observation and hampering data analysis. Efforts have been made to bridge this gap for the major river basins, but little has been done on ice sheets. To address this limitation, we evaluated multiple linear regression (MLR), a back propagation neural network (BPNN), and a deep belief network (DBN) to fill the data gap in Greenland and its six sub-regions. We employed these methods to establish the relationships between precipitation, runoff, evapotranspiration, and ice discharge and GRACE-estimated ice mass changes. A sliding window testing method shows that the BPNN outperformed the two other methods with a root mean square (RMS) error of 1.5 cm in the metrics for the equivalent water height for the whole of Greenland and 1.5-3.6 cm (2.5 cm in average) for the six sub-regions. This accuracy is rather high given an uncertainty of ~ 2 cm in GRACE estimates, but higher for the whole of Greenland than in the sub-regions. This difference was caused by mass leakage error between adjacent sub-regions in the GRACE observations, and can be mitigated by merging these sub-regions. The BPNN predicted ice mass changes agree with the GRACE estimates for long-term and seasonal signals, but are less accurate and precise for interannual signals. Based on the GRACE observations and the BPNN predicted values, we reestimated the ice mass change in Greenland finding that ice loss on Greenland decelerated after mid-2012, primarily due to deceleration in SW, SE, and NE regions.
查看更多>>摘要：Iron-manganese binary oxides (Fe-Mn oxides) have the potential to immobilize arsenite/arsenate [As(III/V)] in situ in natural environments. However, the As(III/V) immobilization performances of Fe-Mn oxides in the presence of indigenous metal-reducing bacteria in reducing groundwater systems have received limited atten-tion. Here, As(III/V) immobilization by Fe-Mn oxides and the interactions of Fe and Mn oxide components in groundwater in the presence of a newly isolated indigenous metal-reducing bacterium (Bacillus sp. FMR) were investigated. Microcosm experiments were performed with artificial groundwater and mineral phases (Fe, Mn and Fe-Mn oxides) with As(III) or As(V) in the presence or absence of strain FMR under anoxic conditions. The Fe oxides in anaerobic cultures without bacteria exhibited better immobilization performances for As(III) [69% As (T) removal efficiency] and As(V) (70%) than Mn oxides (19% and 17%, respectively). Comparably, the involvement of bacteria induced the re-release of arsenic adsorbed on the single Fe and Mn oxides under anoxic conditions, whereas this shift in arsenic adsorption-desorption was not observed in Fe-Mn oxide systems because the Mn oxide components inhibited the reductive dissolution of the Fe oxide components. The As(T) removal efficiencies of Fe-Mn oxides in the presence of bacteria increased by 17% for As(III) and 16% for As(V) compared with anaerobic incubation without bacteria. The interaction of Fe and Mn oxides in Fe-Mn oxides resulted in a slightly increased mobilization of As(III/V) in the absence of bacteria, whereas there was a synergistic effect in the presence of bacteria. The favorability of indigenous bacteria for As(III/V) immobilization and the synergy between Fe and Mn oxides provide novel insights for in-situ As(III/V) immobilization in high arsenic-containing groundwater.
El Shinawi, AbdelazizKuriqi, AlbanZelenakova, MartinaVranayova, Zuzana...
14页
查看更多>>摘要：Land subsidence (LS) due to the Sea Level Rise (SLR) and over-pumping was observed in many groundwater aquifers worldwide. The geotechnical properties and numerical simulation are considered a new integrative approach to investigate the LS hazard. This study investigates the environmental hazards related to LS in the quaternary sediments using laboratory and numerical modeling in the coastal aquifer of Nile delta, Egypt, due to SLR and over-pumping. Therefore, the geotechnical tests are conducted for the aquifer cap and classify the surficial soil as silty clay with moderately complex dispersive characteristics. In addition, hydraulic conductivity and one-dimensional consolidation of silty clay samples were analyzed to estimate the long-term settlement. Consequently, the groundwater head and drawdown were simulated for the current situation. Three proposed future scenarios are SLR and increased abstraction using the SEAWAT code. The results show that groundwater heads increased to 5.65, 14.50, and 26.70 cm for 2020, 2040, and 2060, respectively. Moreover, the estimated LS under the over-pumping scenario reached 7.60, 32.40, and 52.70 cm, with a maximum drawdown of 2.10, 9.70, and 15.10 m. SLR and over-pumping induce more inundation in the northern part due to SLR. The shoreline moves inland with a drawdown to 2, 9.50, and 14.80 m. Integration of measured and groundwater simulation settlements would provide appropriate information about the potential environmental hazards. Moreover, the future LS scenarios help stakeholders to make the right decision in developing effective measures in coastal aquifers to minimize the adverse impacts of LS on infrastructure waterways and human life.
查看更多>>摘要：Vertical circulation well (VCW) is a new type of groundwater heat pump (GWHP) system that is widely used in low-enthalpy geothermal energy utilization. As much attention has been given to the negative environmental impacts of GWHP, cross-formation flow induced by pumping or injection of hot or cold water in storage aquifer should be studied in advance. In this research, a conceptual model of cross-formation flow induced by a thermal VCW in a leaky-confined aquifer is developed and the mathematical implementation of this model is described in an analytical manner. A semi-analytical solution of the spatiotemporal distribution of hydraulic head in the coupled leaky-confined aquifer (in which the VCW is located) and the overlying unconfined aquifer (which is separated from the leaky-confined aquifer by a thin-layer aquitard) is derived using Laplace-Hankel transforms and the solution is tested against a finite-element numerical solution using COMSOL Multiphysics and an existing solution. The global sensitivity analysis is conducted to quantify and prioritize the hydraulic head response to the change in each of the aquifer parameters. The alteration of hydraulic head distribution in the overlying unconfined aquifer induced by the operation of VCW in the underlying leaky-confined aquifer can change the groundwater flow velocity and direction in the unconfined aquifer, thus may cause unwanted environmental consequences. The result indicated that hydraulic head is most sensitive to the hydraulic conductance (C-m) of the aquitard and most insensitive to the length of injection or pumping section of VCW. The proposed semi-analytical solutions can be used to improve the design of vertical single-well circulation system for groundwater treatment or a geothermal energy engineering. This is the phase I research of the thermal VCW concerning mostly the hydraulic response, and it serves as the basis for the phase II research concerning the thermal transport and environmental impact induced by a thermal VCW in the future.
da Rocha, Adolpho Emanuel QuintelaSantos, Eduardo AlvarezPatrignani, Andres
13页
查看更多>>摘要：Partitioning evapotranspiration (ET') into evaporation (E') and plant transpiration (T') is key to understanding ecosystem responses to rainfall variability resulting from climate change. The goal of this study was to quantify T and E using eddy covariance (EC) flux measurements in a tallgrass prairie in consecutive growing seasons with contrasting rainfall regimes. The field measurements were conducted at the National Ecological Observatory Network (NEON) KONZ site, in Kansas, U.S., during the growing seasons of 2017, 2018 and 2019. The ET partitioning was performed using an approach based on the concept of the underlying water use efficiency (uWUE). To evaluate the uWUE approach, we compared daily E estimates obtained from the uWUE with E observations provided by microlysimeters (ML). Green chromatic coordinate (GCC) was used to monitor the vegetation dynamics. In the 2017 growing season, the total rainfall was 23.1% below the site's long-term average cumulative precipitation. On the other hand, in 2018 and 2019 the accumulated growing season precipitations were 7.2% and 40.2%, respectively, above the long-term precipitation average. The relationship between uWUE approach and ML E measurements showed a Pearson correlation coefficient (r) of 0.42 and a root mean square error (RMSE) of 0.58 mm d(-1). The lowest T/ET average value (0.50) was observed in the 2017 growing season, while the largest T/ET average (0.65) was observed in 2018. The correlations between GCC and T/ET were reduced during the growing seasons that experienced drought periods. Air temperature was the main environmental driver of T/ET during the wet growing seasons (r = 0.49 and 0.72). The subsurface soil moisture (0.45 m) was the main environmental driver of T/ET during a dry growing season (r = 0.41). These results demonstrate that the precipitation variability not only has a direct impact on the ET components but also modulates the response of those components to other environmental drivers. Since ET partitioning studies at the ecosystem scale are still scarce, our results can improve T/ET and water use efficiency estimates in long-term modelling studies. This will help to better understand how ET in ecosystems will respond to global warming and increased CO2 concentration during wet and dry growing seasons.
NSTL
Elsevier