The Experts below are selected from a list of 5676 Experts worldwide ranked by ideXlab platform
Raymond H Froend - One of the best experts on this subject based on the ideXlab platform.
-
projected risks to Groundwater dependent terrestrial vegetation caused by changing climate and Groundwater Abstraction in the central perth basin western australia
Hydrological Processes, 2014Co-Authors: Olga Barron, Raymond H Froend, Geoff Hodgson, Riasat Ali, Warrick Dawes, Phil Davies, Don McfarlaneAbstract:The effect of potential climate change on Groundwater-dependent vegetation largely depends on the nature of the climate change (drying or wetting) and the level of current ecosystem dependence on Groundwater resources. In south-western Australia, climate projections suggest a high likelihood of a warmer and drier climate. The paper examines the potential environmental impacts by 2030 at the regional scale on Groundwater-dependent terrestrial vegetation (GDTV) adapted to various watertable depths, on the basis of the combined consideration of Groundwater modelling results and the framework for GDTV risk assessment. The methodology was tested for the historical period from 1984 to 2007, allowing validation of the Groundwater model results' applicability to such an assessment. Climate change effects on GDTV were evaluated using nine global climate models under three greenhouse gas emission scenarios by applying the climate projections to Groundwater models. It was estimated that under dry climate scenarios, GDTV is likely to be under high and severe risk over more than 20% of its current habitat area. The risk is also likely to be higher under an increase in Groundwater Abstraction above current volumes. The significance of climate change risk varied across the region, depending on both the intensity of the change in water regime and the sensitivity of the GDTV to such change. Greater effects were projected for terrestrial vegetation dependent on deeper Groundwater (6–10 m). Copyright © 2013 John Wiley & Sons, Ltd.
-
phreatophytic vegetation response to climatic and Abstraction induced Groundwater drawdown examples of long term spatial and temporal variability in community response
Ecological Engineering, 2010Co-Authors: Raymond H Froend, Beate SommerAbstract:Abstract The influence of climatic drought and Groundwater Abstraction on phreatophytic vegetation dynamics was investigated in the southwest of Western Australia. Two contrasting examples of long-term phreatophytic plant community response to reduced water availability are presented. Multivariate analysis of vegetation and hydrological parameters determined depth to watertable as the dominant biophysical driver of floristic spatial and temporal patterns. Under lower rates of watertable drawdown (9 cm year −1 ), a progressive change in floristic composition was observed over a 33-year period. The abundance of species with a preference for wetter sites was significantly reduced, whereas that of more drought-tolerant species increased. Higher rates of drawdown (50 cm year −1 ) where Groundwater Abstraction exacerbated climatic drought resulted in a threshold response in vegetation and 33% dissimilarity to pre-Abstraction floristics in 12 years. In the context of an ecohydrological state and transition conceptual model, it is suggested higher rates of Groundwater drawdown result in a threshold breach and subsequent transition to an alternative ecohydrological state, whilst lower rates result in a progressive floristic transition.
-
impact of Groundwater Abstraction on a banksia woodland swan coastal plain western australia
Ecological Management and Restoration, 2000Co-Authors: Philip K Groom, Raymond H Froend, Elizabeth M MattiskeAbstract:Summary The Gnangara Groundwater Mound, centred 38 km north of Perth, Western Australia, is a large, shallow unconfined aquifer that is currently under Abstraction as part of the public metropolitan water supply. To investigate the impact of lowering Groundwater levels on a Banksia woodland on the Mound, vegetation monitoring near a Groundwater Abstraction bore (known as P50) began 1 year before becoming operational. In February 1991, 2 years after Abstraction commenced, extensive death of the Banksia overstorey was observed within close proximity of the bore, following a short period of high summer temperatures. The site was subsequently revisited and the understorey floristic composition, abundance and vigour of overstorey species resurveyed, and compared with data collected from a site under long-term monitoring and not currently influenced by Abstraction. A lowering of Groundwater level by 2.2 m at P50 between the summers of 1990 and 1991, resulting from the cumulative effects of Abstraction and below average annual rainfall (low Groundwater recharge), coincided with a loss of between 20 and 80% of adults of overstorey species and up to 64% of adults of understorey species within 200 m of the bore. Over a similar time period no significant decreases in the abundance of overstorey or understorey species were recorded in the monitored site not influenced by Groundwater Abstraction. Of the overstorey species, Holly-leaf Banksia (Banksia ilicifolia) displayed the greatest susceptibility and lowest net recovery following the Abstraction event at P50. The negative impact of Groundwater drawdown on Holly-leaf Banksia populations makes this overstorey species an important indicator of decreasing Groundwater levels on the Gnangara Groundwater Mound. Water stress may have been the primary cause of vegetation death in close proximity to the P50 bore, although this would have been exacerbated by extreme summer temperatures (> 45°C) recorded during February 1991. The P50 scenario represents a localized response to an acute drawdown event, in association with other environmental factors, and provides invaluable information on the assessment of Groundwater Abstraction and poor Groundwater recharge events on a Banksia woodland community. However, there are limitations in using the community response at P50 to manage the impact of drawdown events on other plant communities occurring on sandy, shallow aquifers.
S D P Williams - One of the best experts on this subject based on the ideXlab platform.
-
nonlinear subsidence at fremantle a long recording tide gauge in the southern hemisphere
Journal of Geophysical Research, 2015Co-Authors: Will Featherstone, Nigel T Penna, Michael Filme, S D P WilliamsAbstract:A combination of independent evidence (continuous GPS, repeat geodetic leveling, Groundwater Abstraction, satellite altimetry, and tide gauge (TG) records) shows that the long-recording Fremantle TG has been subsiding in a nonlinear way since the mid-1970s due to time-variable Groundwater Abstraction. The vertical land motion (VLM) rates vary from approximately −2 to −4 mm/yr (i.e., subsidence), thus producing a small apparent acceleration in mean sea level computed from the Fremantle TG records. We exemplify that GPS-derived VLM must be geodetically connected to the TG to eliminate the commonly used assumption that there is no differential VLM when the GPS is not colocated with the TG. In the Perth Basin, we show that Groundwater Abstraction can be used as a diagnostic tool for identifying nonlinear VLM that is not evident in GPS time series alone.
Poul Logstrup Bjerg - One of the best experts on this subject based on the ideXlab platform.
-
relating wellfield drawdown and water quality to aquifer sustainability a method for assessing safe Groundwater Abstraction
Ecological Indicators, 2020Co-Authors: Ryle Norskov Gejl, Poul Logstrup Bjerg, Hans Jorgen Henriksen, Kristian Bitsch, Lars Troldborg, Jorg Schullehner, Jens Rasmussen, Martin RygaardAbstract:Abstract Planning for sustainable Groundwater Abstraction requires realistic and reliable assessments of Groundwater drawdown in aquifers as well as impacted Groundwater-dependent terrestrial and aquatic ecosystems. Present-day impact assessments allocate water for the environment and ecosystems in the form of environmental Groundwater requirements (EGWRs). However, securing sustainable Groundwater Abstraction also requires stable Groundwater quality for consumers and receptors (e.g. streams and Groundwater-dependent ecosystems). We suggest dividing EGWR into two parts, namely EGWRflow, related to impacts on surface water, and EGWRwq, related to impacts on Groundwater quality. We then propose a method for modelling maximum safe Groundwater Abstraction rates based on a relationship between water quality and piezometric heads. The method provides estimations of sustainable Abstraction rates that secure stable water quality and maintain water security. Using hydrological modelling, we estimated spatially differentiated EGWRwq, for Zealand, Denmark, based on three different conditioned drawdowns of 3, 6 and 9 m. We found that depending on the boundaries and the different conditioned drawdowns EGWRwq poses a 2.5–83% share of the Groundwater recharge. We found that a redistribution of water Abstraction would make 27 million m3 available compared with actual Abstraction, dependent on scale, while keeping within a conditioned drawdown of 3 m. Our results demonstrate how conditioned drawdown can be implemented with the objectives of evaluating actual Abstraction and securing stable water quality, hence comprising a step towards more reliable and relevant Groundwater impact assessments.
-
understanding the impacts of Groundwater Abstraction through long term trends in water quality
Water Research, 2019Co-Authors: Ryle Norskov Gejl, Hans Jorgen Henriksen, Martin Rygaard, Jes J Rasmussen, Poul Logstrup BjergAbstract:Abstract It is vital to understand long-term trends in water quality parameters when assessing the sustainability of Groundwater Abstraction. Withdrawal-to-availability analysis is still used widely in Groundwater management considering quantities and utilization rates based on in- and outflows. In this study, we took a step further than the water balance approach and carried out a detailed investigation of trends in long-term time series of Groundwater quality, in order to analyze the sustainability of Groundwater Abstraction. We assessed trends, links, and patterns in Abstraction, potentiometric surface, and water quality parameters for 28 well fields around Copenhagen, Denmark. Groundwater monitoring data from 1900 until 2014 were investigated for each well field. During this period, the well fields experienced a 2–14 m decrease in the nearby potentiometric surface compared to the first—or pre-pumping—potentiometric surface recordings. Sulfate concentrations increased in 25 out of 27 well fields after the maximum Abstraction period, compared to the earliest water quality measurements. The results indicate that in the 1980s, when water consumption (Abstraction) and drawdown were at their highest, water Abstraction caused a steady increase in sulfate and calcium, which we consider unsustainable. In contradiction, the Abstraction in 24 well fields show almost steady sulfate levels in the aquifer after decreased water consumption since 1995. Only four well fields showed more than a 20 mg/L increase in sulfate concentration, which indicates that the recent Abstraction does not interfere with sulfate levels in the aquifer. Our method and results show how long-term water quality trends can support the management of aquifer exploitation and evaluate sustainability on the well field scale.
Paul J Wood - One of the best experts on this subject based on the ideXlab platform.
-
macroinvertebrate community responses to hydrological controls and Groundwater Abstraction effects across intermittent and perennial headwater streams
Science of The Total Environment, 2018Co-Authors: James C White, Andy House, Neil Punchard, David M Hannah, Nicholas A Wilding, Paul J WoodAbstract:Intermittent rivers comprise a significant proportion of river networks globally and their spatial extent is predicted to increase with rising water Abstraction pressures. Despite this, the ecological implications of hydrological modifications within intermittent rivers have received limited research attention. This paper examines macroinvertebrate assemblages across intermittent and perennial sections of headwater streams within the Hampshire Avon catchment (United Kingdom) over a five-year period. The composition of faunal assemblages was quantified in relation to four hydrological metrics: the duration of flowing conditions, the geographical proximity to the nearest perennial source along each watercourse (two observed flow parameters) and two modelled Groundwater Abstraction influences. The results highlight that macroinvertebrate communities inhabiting sites which dry periodically and are positioned at greater distances (> c. 2.5 km) above the perennial source (the most upstream point of permanent flow within a given year) possessed the highest conservation values. These sites supported species that are rare in many areas of Europe (e.g. Ephemeroptera: Paraletophlebia werneri) or with limited geographical distribution across the United Kingdom (e.g. Trichoptera: Limnephilus bipunctatus). A range of faunal community diversity indices were found to be more sensitive to the antecedent flow duration and distance from the perennial source, rather than any effects of Groundwater Abstraction. Taxonomic richness responded most strongly to these observed flow parameters and varied more markedly with the distance from the perennial source compared to the antecedent flow duration. Several taxa were significantly associated with the observed flow parameters, particularly those predominantly inhabiting perennially flowing systems. However, the distance that such fauna could migrate into intermittent reaches varied between taxa. This research demonstrates the overriding importance of antecedent flow durations and the geographical proximity to perennial sources on macroinvertebrate communities within intermittent and perennial headwater streams.
-
supplementary information files for macroinvertebrate community responses to hydrological controls and Groundwater Abstraction effects across intermittent and perennial headwater streams
2017Co-Authors: James C White, Andy House, Neil Punchard, David M Hannah, Nicholas A Wilding, Paul J WoodAbstract:Supplementary information files for "Macroinvertebrate community responses to hydrological controls and Groundwater Abstraction effects across intermittent and perennial headwater streams"Intermittent rivers comprise a significant proportion of river networks globally and their spatial extent is predicted to increase with rising water Abstraction pressures. Despite this, the ecological implications of hydrological modifications within intermittent rivers have received limited research attention. This paper examines macroinvertebrate assemblages across intermittent and perennial sections of headwater streams within the Hampshire Avon catchment (United Kingdom) over a five-year period. The composition of faunal assemblages was quantified in relation to four hydrological metrics: the duration of flowing conditions, the geographical proximity to the nearest perennial source along each watercourse (two observed flow parameters) and two modelled Groundwater Abstraction influences. The results highlight that macroinvertebrate communities inhabiting sites which dry periodically and are positioned at greater distances (> c. 2.5 km) above the perennial source (the most upstream point of permanent flow within a given year) possessed the highest conservation values. These sites supported species that are rare in many areas of Europe (e.g. Ephemeroptera: Paraletophlebia werneri) or with limited geographical distribution across the United Kingdom (e.g. Trichoptera: Limnephilus bipunctatus). A range of faunal community diversity indices were found to be more sensitive to the antecedent flow duration and distance from the perennial source, rather than any effects of Groundwater Abstraction. Taxonomic richness responded most strongly to these observed flow parameters and varied more markedly with the distance from the perennial source compared to the antecedent flow duration. Several taxa were significantly associated with the observed flow parameters, particularly those predominantly inhabiting perennially flowing systems. However, the distance that such fauna could migrate into intermittent reaches varied between taxa. This research demonstrates the overriding importance of antecedent flow durations and the geographical proximity to perennial sources on macroinvertebrate communities within intermittent and perennial headwater streams.
Marc F. P. Bierkens - One of the best experts on this subject based on the ideXlab platform.
-
the effects of Groundwater Abstraction on low flows
EGU General Assembly Conference Abstracts, 2012Co-Authors: I E M De Graaf, L P H Van Beek, Y Wada, Marc F. P. BierkensAbstract:In regions with frequent water stress and large aquifer systems, Groundwater often constitutes an essential source of water. If Groundwater Abstraction exceeds Groundwater recharge over a long time and over large areas persistent Groundwater depletion can occur. The resulting lowering of Groundwater levels can have negative effects on agricultural productivity but also on natural streamflow and associated wetlands and ecosystems, in particular during low-flow events when the Groundwater contribution through baseflow is relatively large. In this study we focus on the effects of global Groundwater Abstraction on low-flow magnitude, frequency and duration for the major rivers of the world for the period 1960-2000. As a basis, we use the large-scale hydrological model PCR-GLOBWB that calculates all major water balance terms on a daily time step at a 0.5ox0.5o resolution. Currently, PCR-GLOBWB represents Groundwater and the associated baseflow by means of a linear reservoir that is parameterized using global lithological data and drainage density. It simulates renewable Groundwater storage within each 0.5o cell. Lateral flow between cells is not considered. The specific runoff from the model is subsequently transformed into discharge by means of a kinematic wave routing scheme.
-
Nonsustainable Groundwater sustaining irrigation: A global assessment
Water Resources Research, 2012Co-Authors: Yoshihide Wada, Ludovicus P H Van Beek, Marc F. P. BierkensAbstract:Water used by irrigated crops is obtained from three sources: local precipitation contributing to soil moisture available for root water uptake (i.e., green water), irrigation water taken from rivers, lakes, reservoirs, wetlands, and renewable Groundwater (i.e., blue water), and irrigation water abstracted from nonrenewable Groundwater and nonlocal water resources. Here we quantify globally the amount of nonrenewable or nonsustainable Groundwater Abstraction to sustain current irrigation practice. We use the global hydrological model PCR-GLOBWB to simulate gross crop water demand for irrigated crops and available blue and green water to meet this demand. We downscale country statistics of Groundwater Abstraction by considering the part of net total water demand that cannot be met by surface freshwater. We subsequently confront these with simulated Groundwater recharge, including return flow from irrigation to estimate nonrenewable Groundwater Abstraction. Results show that nonrenewable Groundwater Abstraction contributes approximately 20% to the global gross irrigation water demand for the year 2000. The contribution of nonrenewable Groundwater Abstraction to irrigation is largest in India (68 km3 yr−1) followed by Pakistan (35 km3 yr−1), the United States (30 km3 yr−1), Iran (20 km3 yr−1), China (20 km3 yr−1), Mexico (10 km3 yr−1), and Saudi Arabia (10 km3 yr−1). Results also show that globally, this contribution more than tripled from 75 to 234 km3 yr−1 over the period 1960–2000.
-
global depletion of Groundwater resources
Geophysical Research Letters, 2010Co-Authors: Yoshihide Wada, Ludovicus P H Van Beek, Cheryl M Van Kempen, Josef W T M Reckman, Slavek Vasak, Marc F. P. BierkensAbstract:[1] In regions with frequent water stress and large aquifer systems Groundwater is often used as an additional water source. If Groundwater Abstraction exceeds the natural Groundwater recharge for extensive areas and long times, overexploitation or persistent Groundwater depletion occurs. Here we provide a global overview of Groundwater depletion (here defined as Abstraction in excess of recharge) by assessing Groundwater recharge with a global hydrological model and subtracting estimates of Groundwater Abstraction. Restricting our analysis to sub-humid to arid areas we estimate the total global Groundwater depletion to have increased from 126 (±32) km3 a−1 in 1960 to 283 (±40) km3 a−1 in 2000. The latter equals 39 (±10)% of the global yearly Groundwater Abstraction, 2 (±0.6)% of the global yearly Groundwater recharge, 0.8 (±0.1)% of the global yearly continental runoff and 0.4 (±0.06)% of the global yearly evaporation, contributing a considerable amount of 0.8 (±0.1) mm a−1 to current sea-level rise.
