The argument that human society can decouple economic growth-defined as growth in Gross Domestic Product (GDP)-from growth in environmental impacts is appealing. If such decoupling is possible, it ...means that GDP growth is a sustainable societal goal. Here we show that the decoupling concept can be interpreted using an easily understood model of economic growth and environmental impact. The simple model is compared to historical data and modelled projections to demonstrate that growth in GDP ultimately cannot be decoupled from growth in material and energy use. It is therefore misleading to develop growth-oriented policy around the expectation that decoupling is possible. We also note that GDP is increasingly seen as a poor proxy for societal wellbeing. GDP growth is therefore a questionable societal goal. Society can sustainably improve wellbeing, including the wellbeing of its natural assets, but only by discarding GDP growth as the goal in favor of more comprehensive measures of societal wellbeing.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Display omitted
•A comprehensive review of sea-level rise impacts on coastal aquifers is presented.•The main remaining challenges for future research opportunities are presented.•The need for an ...integrated assessment of controlling factors is identified.•Both analytical and numerical models are employed to investigate influential factors in an integrated framework.•Sensitivity assessment based on dimensionless parameters is implemented to scrutinize influential factors.
Sea-level rise (SLR) influences groundwater hydraulics and in particular seawater intrusion (SWI) in many coastal aquifers. The quantification of the combined and relative impacts of influential factors on SWI has not previously been considered in coastal aquifers. In the present study, a systematic review of the available literature on this topic is first provided. Then, the potential remaining challenges are scrutinized. Open questions on the effects of more realistic complexities such as gradual SLR, parameter uncertainties, and the associated influences in decision-making models are issues requiring further investigation.
We assess and quantify the seawater toe location under the impacts of SLR in combination with recharge rate variations, land-surface inundation (LSI) due to SLR, aquifer bed slope variation, and changing landward boundary conditions (LWBCs). This is the first study to include all of these factors in a single analysis framework. Both analytical and numerical models are used for these sensitivity assessments. It is demonstrated that (1) LSI caused by SLR has a significant incremental impact on the seawater toe location, especially in the flatter coasts and the flux-controlled (FC) LWBCs, however this impact is less than the reported orders of magnitude differences which were estimated using only analytical solutions; (2) LWBCs significantly influence the SLR impacts under almost all conditions considered in this study; (3) The main controlling factors of seawater toe location are the magnitudes of fresh groundwater discharge to sea and recharge rate. Regional freshwater flux entering from the landward boundary and the groundwater hydraulic gradient are the major contributors of fresh groundwater discharge to sea for both FC and head-controlled (HC) systems, respectively; (4) A larger response of the aquifer and larger seawater toe location changes are demonstrable for a larger ratio of the aquifer thickness to the aquifer length particularly in the HC systems; (5) The lowest sensitivity of seawater toe location is found for the density difference ratio of the seawater and freshwater, and also for the aquifer bed slope; (6) The early-time observations show seawater fingers below the inundated lands due to SLR which are diminished and ultimately extinguished; and (7) A less than 2% reversal effect on the seawater toe location after overshoot mechanism is observed in the transient simulations which suggests that this mechanism is an insignificant and impractical factor compared to other more significant factors.
Despite its purported importance, previous studies of the influence of sea‐level rise on coastal aquifers have focused on specific sites, and a generalized systematic analysis of the general case of ...the sea water intrusion response to sea‐level rise has not been reported. In this study, a simple conceptual framework is used to provide a first‐order assessment of sea water intrusion changes in coastal unconfined aquifers in response to sea‐level rise. Two conceptual models are tested: (1) flux‐controlled systems, in which ground water discharge to the sea is persistent despite changes in sea level, and (2) head‐controlled systems, whereby ground water ions or surface features maintain the head condition in the aquifer despite sea‐level changes. The conceptualization assumes steady‐state conditions, a sharp interface sea water‐fresh water transition zone, homogeneous and isotropic aquifer properties, and constant recharge. In the case of constant flux conditions, the upper limit for sea water intrusion due to sea‐level rise (up to 1.5 m is tested) is no greater than 50 m for typical values of recharge, hydraulic conductivity, and aquifer depth. This is in striking contrast to the constant head cases, in which the magnitude of salt water toe migration is on the order of hundreds of meters to several kilometers for the same sea‐level rise. This study has highlighted the importance of inland boundary conditions on the sea‐level rise impact. It identifies combinations of hydrogeologic parameters that control whether large or small salt water toe migration will occur for any given change in a hydrogeologic variable.
Lake Urmia (LU) is the second largest hypersaline lake in the world. Lake Urmia's water level has dropped drastically from 1277.85 m to 1270.08 m a.s.l (equal to 7.77 m) during the last 20 years, ...equivalent to a loss of 70% of the lake area. The likelihood of lake-groundwater connection on the basin-scale is uncertain and understudied because of lack of basic data and precise information required for physically-based modeling. In this study, cross-correlation analysis is applied on a various time-frames of water level of the lake and groundwater levels (2001–2018) recorded in 797 observation wells across 17 adjacent aquifers. This provides insightful information on the lake-groundwater interaction. The cross-correlation coefficient between the monthly water level of lake and observations wells (rGW−L) and the difference of these two variables (Hf) was calculated for different time-frames. The values of rGW−L (ranged −0.69 to 0.97) and Hf (ranged −53 m to 293 m) indicated the significant role of time-frames of observed dataset on dynamic behavior of lake-groundwater interaction, and exchange fluxes in the study setting. Results suggested two opposing behaviors in lake-groundwater interaction of the study system mainly arise from anthropogenic activity (overexploitation of groundwater for irrigation) and aquifer type (unconfined/pressurized): three out of 17 adjacent aquifers are feeding by the LU and act as “gaining aquifers” (located in northern half of LU) and others discharging into the LU and act as “losing aquifers”. This study aimed to provide easy-to-obtain insights into LGWI in the complex setting of LU Basin. It can be considered a preliminary step towards a deeper understanding of the interaction through physically-based analysis and modeling.
Display omitted
•Cross-correlation analysis between water level of Lake Urmia and adjacent aquifers is calculated.•A dynamic equilibrium observed between Lake Urmia and surrounding groundwater•The Lake Urmia recharged from the 15 aquifers and only two aquifers exfiltrates the lake.•Lake Urmia's water level is strongly affected by the groundwater levels in the adjacent aquifers.•The decline of the Lake Urmia's water level is correlated to the number of drilled pumping wells.
Drought is an intermittent disturbance of the water cycle that profoundly affects the terrestrial carbon cycle. However, the response of the coupled water and carbon cycles to drought and the ...underlying mechanisms remain unclear. Here we provide the first global synthesis of the drought effect on ecosystem water use efficiency (WUE = gross primary production (GPP)/evapotranspiration (ET)). Using two observational WUE datasets (i.e., eddy-covariance measurements at 95 sites (526 site-years) and global gridded diagnostic modelling based on existing observation and a data-adaptive machine learning approach), we find a contrasting response of WUE to drought between arid (WUE increases with drought) and semi-arid/sub-humid ecosystems (WUE decreases with drought), which is attributed to different sensitivities of ecosystem processes to changes in hydro-climatic conditions. WUE variability in arid ecosystems is primarily controlled by physical processes (i.e., evaporation), whereas WUE variability in semi-arid/sub-humid regions is mostly regulated by biological processes (i.e., assimilation). We also find that shifts in hydro-climatic conditions over years would intensify the drought effect on WUE. Our findings suggest that future drought events, when coupled with an increase in climate variability, will bring further threats to semi-arid/sub-humid ecosystems and potentially result in biome reorganization, starting with low-productivity and high water-sensitivity grassland.
•Three types of transpiration (Ec) models are compared at daily and hourly scales.•Penman-Monteith method is outperformed by two other models at the hourly scale.•Models with four environmental ...variables perform better than those with reduced variables.•Including soil water function is more important at the daily than hourly scale.•Parameter values in Ec models are not transferable across daily and hourly scales.
Tree water use (Ec) can be simulated from environmental variables. Such Ec models can be categorized as firstly the Penman-Monteith (PM) equation where canopy conductance (gc) is simulated from the Jarvis-Stewart (JS) approach, secondly the models modified from the JS approach that link Ec directly with environmental variables (MJS), avoiding the calculation of gc, and thirdly process-based models that incorporate plant physiological functions. Tree water use and canopy conductance are constrained by the root-zone soil water supply and atmospheric demand (e.g., radiation, temperature, humidity and wind speed). This study aims to determine which type of Ec models performs better at the daily and hourly scales, and which influencing factors are more critical for Ec modeling at each time scale. The transferability of parameter values across temporal scales is also examined as this is a common issue that modelers need to deal with. The results show that the MJS and a simplified process-based model (BTA) models produce generally better simulations than the PM models at the hourly scale, and the best PM model gives comparable results to the best MJS model at the daily scale. BTA fails at the daily scale on the tree under water stress likely due to its incorporation of soil water availability into an integrated parameter. Soil water content function is more important for daily Ec modeling than hourly in all models. For MJS models, soil water content function has a stronger influence than air temperature on hourly Ec modeling, while no significant difference is observed in the PM models. Parameter values are not transferrable across temporal scales; and calibrating parameters in each season rather than in the first a number of days of all seasons improves Ec simulations.
River‐groundwater interactions are at the core of a wide range of major contemporary challenges, including the provision of high‐quality drinking water in sufficient quantities, the loss of ...biodiversity in river ecosystems, or the management of environmental flow regimes. This paper reviews state of the art approaches in characterizing and modeling river and groundwater interactions. Our review covers a wide range of approaches, including remote sensing to characterize the streambed, emerging methods to measure exchange fluxes between rivers and groundwater, and developments in several disciplines relevant to the river‐groundwater interface. We discuss approaches for automated calibration, and real‐time modeling, which improve the simulation and understanding of river‐groundwater interactions. Although the integration of these various approaches and disciplines is advancing, major research gaps remain to be filled to allow more complete and quantitative integration across disciplines. New possibilities for generating realistic distributions of streambed properties, in combination with more data and novel data types, have great potential to improve our understanding and predictive capabilities for river‐groundwater systems, especially in combination with the integrated simulation of the river and groundwater flow as well as calibration methods. Understanding the implications of different data types and resolution, the development of highly instrumented field sites, ongoing model development, and the ultimate integration of models and data are important future research areas. These developments are required to expand our current understanding to do justice to the complexity of natural systems.
Key Points
Recent breakthroughs in fields such as geostatistics, analytical chemistry, remote sensing, or data assimilation are discussed
The relevance of these emerging approaches in characterizing streambeds and modeling river‐groundwater interactions is reviewed
Integrating approaches across a range of spatial and temporal scales moves our current conceptual models toward the complexity of natural systems
•Polynomial chaos expansions (PCEs) are applied to seawater intrusion modeling.•PCEs can be accurate and fast surrogate models in Monte Carlo simulations.•PCEs can be reliably used in the estimation ...of moment-independent sensitivity indices.
Real world models of seawater intrusion (SWI) require high computational efforts. This creates computational difficulties for the uncertainty propagation (UP) analysis of these models due the need for repeated numerical simulations in order to adequately capture the underlying statistics that describe the uncertainty in model outputs. Moreover, despite the obvious advantages of moment-independent global sensitivity analysis (SA) methods, these methods have rarely been employed for SWI and other complex groundwater models. The reason is that moment-independent global SA methods involve repeated UP analysis which further becomes computationally demanding. This study proposes the use of non-intrusive polynomial chaos expansions (PCEs) as a means to significantly accelerate UP analysis in SWI numerical modeling studies and shows that despite the highly non-linear and non-smooth input/output relationship that exists in SWI models, non-intrusive PCEs provide a reliable and yet computationally efficient surrogate of the original numerical model. The study illustrates that for the considered two and six dimensional UP problems, PCEs offer a more accurate estimation of the statistics describing the uncertainty in model outputs compared to Monte Carlo simulations based on the original numerical model. This study also shows that the use of non-intrusive PCEs in the estimation of the moment-independent sensitivity indices (i.e. delta indices) decreases the computational time by several orders of magnitude without causing significant loss of accuracy. The use of non-intrusive PCEs for the generation of SWI hazard maps is proposed to extend the practical applications of UP analysis in coastal aquifer management studies.
Assessing environmentally sustainable GW management (ESGM) needs a deep knowledge of the present and the projected status of GW (GW) quantity and quality. Translations of these data into policy ...relevant information are usually done through quantitative indices. Despite the availability of a dozen GW sustainability indicators, defining an integrated index based on internationally accepted scientific standards indicators is required. To fill this gap, an in-depth review on the developed indicators/index for evaluation of GW sustainable management (GWSM) from an environmental viewpoint at aquifer scales is provided in this study. Thirteen environmentally related quantitative indicators are adopted for assessment of GWSM, especially in arid regions, depending upon data availability, and relevance of indicators. An integrated ESGM index (ESGMI) is developed based on weighted aggregation of thirteen adopted indicators through multi criteria decision making (MCDM) methods. ESGMI value ranged between 0 and 100, zero value denotes to the worst state or unsustainable GW management (GWM) and 100 indicates the ideal state or GWM is sustainable. Thirty important aquifers across Iran are chosen to implement the ESGMI at the national scale of a country known to be the fifth largest global GW user. ESGMI values for thirty of Iran's aquifers are obtained in the range 15.40 to 68.50 (on average, 49.96). This reveals the unsustainable status of GWM in this country. The results of this study demonstrate that the ESGMI is a promising tool to determine the current state of GW quantity and quality, reveals the effect of policy actions and plans, and contributes to the development and operation of effective sustainable management policies for GW resources. Due to uncertainties and spatio-temporal variabilities of key controlling variables in GW management, sustainability evaluation should be understood as a dynamic and iterative process, requiring persistent monitoring, analysis, prioritization, and modification.
Display omitted
•In-depth review on the environmental indicators for evaluation of GWSM is provided.•Thirteen indicators are adopted and aggregated through MCDM to obtain ESGMI index.•Thirty key aquifers across Iran are adopted to implement the ESGMI.•ESGMI is a promising tool to detect the current status of GW quality and quantity.•ESGMI can contribute to development of effective sustainable management policies.
PDF
