Evidence for invasive carp mediated trophic cascade in shallow lakes of western Victoria, Australia
- Authors: Khan, Tariq , Wilson, Michael , Khan, Minal
- Date: 2003
- Type: Text , Journal article
- Relation: Hydrobiologia Vol. 506-509, no. (2003), p. 465-472
- Full Text: false
- Reviewed:
- Description: Lakes of western Victoria are typically shallow (2-3 m), slightly saline (3-8 ppt) and eutrophic (total phosphorus 0.1-5 mg l-1 and total nitrogen 3-8 mg l-1). These lakes are prone to algal blooms in late spring and summer. We conducted experiments in ponds to determine whether lake zooplankton exert enough grazing pressure to control algal blooms and also if carp predation can regulate zooplankton communities and increase algal biomass. Zooplankton grazing (high zooplankton, low zooplankton and control) and carp predation (carp, nutrient and control) experiments had three treatments and each treatment had three replicates. Algal numbers and biomass (28
- Description: C1
- Description: 2003000543
Beyond hydrogeologic evidence : Challenging the current assumptions about salinity processes in the Corangamite region, Australia
- Authors: Dahlhaus, Peter , Cox, Jim , Simmons, Craig , Smitt, C. M.
- Date: 2008
- Type: Text , Journal article
- Relation: Hydrogeology Journal Vol. 16, no. 7 (2008), p. 1283-1298
- Full Text:
- Reviewed:
- Description: In keeping with the standard scientific methods, investigations of salinity processes focus on the collection and interpretation of contemporary scientific data. However, using multiple lines of evidence from non-hydrogeologic sources such as geomorphic, archaeological and historical records can substantially add value to the scientific investigations. By using such evidence, the validity of the assumptions about salinity processes in Australian landscapes is challenged, especially the assumption that the clearing of native vegetation has resulted in rising saline groundwater in all landscapes. In the Corangamite region of south-west Victoria, salinity has been an episodic feature of the landscapes throughout the Quaternary and was present at the time of the Aboriginal inhabitants and the first pastoral settlement by Europeans. Although surface-water salinity has increased in some waterways and the area of salinised land has expanded in some landscapes, there is no recorded evidence found which supports significant rises in groundwater following widespread land-use change. In many areas, salinity is an inherent component of the region's landscapes, and sustains world-class environmental assets that require appropriate salinity levels for their ecological health. Managing salinity requires understanding the specific salinity processes in each landscape. © Springer-Verlag 2008.
Macroinvertebrate communities in Phragmites australis (Cav.) Trin. ex Steud. reed beds and open bank habitats in central Victorian streams in Australia
- Authors: Jayawardana, Chandamali , Westbrooke, Martin , Wilson, Michael , Hurst, Cameron
- Date: 2006
- Type: Text , Journal article
- Relation: Hydrobiologia Vol. 568, no. 1 (2006), p. 169-185
- Full Text: false
- Reviewed:
- Description: Reed invasion is a common phenomenon of open streams with disturbed riparian vegetation in river catchments. Knowledge of the effects of such vegetation change on aquatic communities is fundamental to river management. Macroinvertebrate fauna in Phragmites australis (Cav.) Trin. ex Steud. and open bank habitats were examined in three rivers in central Victoria in order to understand the effect of such littoral habitat on macroinvertebrates. Data were analysed using Partially Nested Factorial ANOVA with season, river and habitats as main effects. Habitat structure had a significant effect (p < 0.05) on macroinvertebrate species richness, however this was not seasonally consistent across the three rivers. There was a significant increase (p < 0.05) in macroinvertebrate taxa richness in Phragmites habitats during winter and spring seasons. Total abundance of taxa showed no consistent significant differences in the two habitats. Results of Canonical Analysis of Principle Coordinates indicated significant differences (p < 0.05) in macroinvertebrate assemblages between Phragmites and bare bank habitats in all seasons. Habitat selection by taxa could be related to the microphysical environment of the habitats. This study suggests that reed beds create important littoral habitat structures which support diverse macroinvertebrate assemblages. © Springer 2006.
- Description: C1
- Description: 2003001589
Groundwater-level response to land-use change and the implications for salinity management in the West Moorabool River catchment, Victoria, Australia
- Authors: Dahlhaus, Peter , Evans, Timothy , Nathan, Erica , Cox, Jim , Simmons, Craig
- Date: 2010
- Type: Text , Journal article
- Relation: Hydrogeology Journal Vol. 18, no. 7 (2010), p. 1611-1623
- Full Text: false
- Reviewed:
- Description: The connection between the removal of native vegetation, rising water tables and increasing stream salinity has been established for many catchments across Australia. However, the West Moorabool River in south west Victoria is an example of a catchment where there has been little discernable effect on groundwater levels following land clearing. Over the past 150 years, a significant portion of the catchment has been cleared of dense forest for agricultural development. Historic standing water-level records from 1870-1871 and 1881 are compared with contemporary measurements (1970s to 2007) recorded in the government bore databases. The data show that the earliest recorded groundwater levels are well within the seasonal range of values observed today. By integrating geology and hydrogeology with historical observations of groundwater levels, climate data and land use, the contemporary field observations of stream salinity are linked to the changed water use and shift in rainfall. In contrast to the normally accepted axiom, reafforestation as a management strategy to mitigate the rising salinity in the West Moorabool River catchment would seem inappropriate. © 2010 Springer-Verlag.
- Description: The connection between the removal of native vegetation, rising water tables and increasing stream salinity has been established for many catchments across Australia. However, the West Moorabool River in south west Victoria is an example of a catchment where there has been little discernable effect on groundwater levels following land clearing. Over the past 150 years, a significant portion of the catchment has been cleared of dense forest for agricultural development. Historic standing water-level records from 1870-1871 and 1881 are compared with contemporary measurements (1970s to 2007) recorded in the government bore databases. The data show that the earliest recorded groundwater levels are well within the seasonal range of values observed today. By integrating geology and hydrogeology with historical observations of groundwater levels, climate data and land use, the contemporary field observations of stream salinity are linked to the changed water use and shift in rainfall. In contrast to the normally accepted axiom, reafforestation as a management strategy to mitigate the rising salinity in the West Moorabool River catchment would seem inappropriate. © 2010 Springer-Verlag.
Increasing the understanding and use of natural archives of ecosystem services, resilience and thresholds to improve policy, science and practice
- Authors: Pearson, Stuart , Lynch, Jasmyn , Plant, Roel , Cork, Steve , Taffs, Kathryn , Dodson, John , Maynard, Simone , Gergis, Joelle , Gell, Peter , Thackway, Richard , Sealie, Lynne , Donaldson, Jim
- Date: 2015
- Type: Text , Journal article
- Relation: Holocene Vol. 25, no. 2 (2015), p. 366-378
- Full Text: false
- Reviewed:
- Description: Despite the great potential of palaeo-environmental information to strengthen natural resource policy, science and practical outcomes naturally occurring archives of palaeo-environmental and ecosystem service information have not been fully recognised or utilised to inform the development of environmental policy. In this paper, we describe how Australian palaeo-environmental science is improving environmental understanding through local studies and regional syntheses that inform us about past conditions, extreme conditions and altered ecosystem states. Australian innovations in ecosystem services research and palaeo-environmental science contribute in five important contexts: discussions about environmental understanding and management objectives, improving access to information, improved knowledge about the dynamics of ecosystem services, increasing understanding of environmental processes and resource availability, and engaging interdisciplinary approaches to manage ecosystem services. Knowledge of the past is an important starting point for setting present and future resource management objectives, anticipating consequences of trade-offs, sharing risk and evaluating and monitoring the ongoing availability of ecosystem services. Palaeo-environmental information helps reframe discussions about desirable futures and collaborative efforts between scientists, planners, managers and communities. However, further steps are needed to translate the ecosystem services concept into ecosystem services policy and tangible management objectives and actions that are useful, feasible and encompass the range of benefits to people from ecosystems. We argue that increased incorporation of palaeo-environmental information into policy and decision-making is needed for evidence-based adaptive management to enhance sustainability of ecosystem functions and reduce long-term risks.
The sedimentary record of palaeoenvironments and sea-level change in the Gulf of Carpentaria, Australia, through the last glacial cycle
- Authors: Reeves, Jessica , Chivas, Allan , Garcia, Adriana , Holt, Sabine , Couapel, Martine , Jones, Brian , Cendón, Dioni , Fink, David
- Date: 2008
- Type: Text , Journal article
- Relation: Quaternary International Vol. 183, no. 1 (2008), p. 3-22
- Full Text: false
- Reviewed:
- Description: Environmental evolution of the Gulf of Carpentaria region, the world's largest tropical epicontinental seaway, through the last glacial cycle has been determined from a series of six sediment cores. These cores form the focus of a multi-disciplinary study to elucidate sea level, climate and environmental change in the region. The sedimentary record reveals a series of facies including open shallow marine, marginal marine, estuarine, lacustrine and subaerial exposure, throughout the extent of the basin during this period. The partial or complete closure of the central basin from marine waters results from sea level falling below the height of one or both of the sills that border the Gulf-the Arafura Sill to the west (53 m below present sea level (bpsl)) and Torres Strait to the east (12 m bpsl). The extent and timing of these closures, and restriction of the shallow waterbody within, are intrinsic to local ocean circulation, available latent heat transport and the movement of people and animals between Australia and New Guinea. Whilst the occurrence of the palaeo-Lake Carpentaria has previously been identified, this study expands on the hydrological conditions of the lacustrine phases and extends the record through the Last Interglacial, detailing the previous sea-level highstand (MIS 5.5) and subsequent retreat. When sea levels were low during the MIS 6 glacial period, the Gulf was largely subaerially exposed and traversed by meandering rivers. The MIS 5 transgression (∼130 ka BP) led to marine then alternating marine/estuarine conditions through to MIS 4 (∼70 ka BP) when a protracted lacustrine phase, of varying salinity and depth/area, and including periods of near desiccation, persisted until about 12.2 cal ka BP. The lake expanded to near maximum size (∼190 000 km2) following the intensification/restoration of the Australian monsoon at 14 ka BP. This lake-full phase was short-lived, as by 12.2 cal ka BP, marine waters were entering the basin, coincident with the progressive sea-level rise. Fully marine conditions were restored by about 10.5 cal ka BP by westward connection to the Arafura Sea (Indian Ocean), whereas connections to the Pacific Ocean (Coral Sea) did not occur until about 8 cal ka BP.
- Description: C1
Oscillations of sea level rise along the Atlantic coast of North America north of Cape Hatteras
- Authors: Parker, Albert
- Date: 2013
- Type: Text , Journal article
- Relation: Natural Hazards Vol. 65, no. 1 (2013), p. 991-997
- Full Text: false
- Reviewed:
- Description: It is shown in the short comment that the sea levels are oscillating about a longer-term trend and that the sea level rise (SLR) computed with time windows of 20, 30 or 60 years also oscillates, with the amplitude of these latter oscillations reducing as the time window increases. The use of only two values of the SLR distribution is misleading to infer conclusions about the accelerating behaviour. In particular, the comparison of the 30-year SLR 1950-1979 with the 30-year SLR 1980-2009 for the tide gauges along the Atlantic coast of North America north of Cape Hatteras to infer an accelerating behaviour is particularly wrong because the 30-year time window is a too short interval to appreciate the longer-term sea level trend cleared of the multi-decadal oscillations, and the two values from the SLR distribution are computed, respectively, at the times of a valley and a peak for the 60-year Atlantic Ocean multi-decadal oscillation. By using a 60-year time window or all the data since opening when more than 60 years of recording are available and by analysing the SLR time history, the only conclusion that can be inferred from the analysis of the tide gauges along the North American Atlantic coast is that the sea levels are oscillating without too much of a positive acceleration along their longer-term trend. © 2012 Springer Science+Business Media B.V.
- Description: 2003010586
Diatom-based models for inferring past water chemistry in western Ugandan crater lakes
- Authors: Mills, Keely , Ryves, David
- Date: 2012
- Type: Text , Journal article
- Relation: Journal of Paleolimnology Vol. 48, no. 2 (2012), p. 383-399
- Full Text: false
- Reviewed:
- Description: Diatom surface sediment samples and corresponding water chemistry were collected from 56 lakes across a natural conductivity gradient in western Uganda (reflecting a regional climatic gradient of effective moisture) to explore factors controlling diatom distribution. Here we develop a regional training set from these crater lakes to test the hypothesis that this approach, by providing more appropriate and closer analogues, can improve the accuracy of palaeo-conductivity reconstructions, and so environmental inferences in these lake systems compared to larger training sets. We compare this output to models based on larger, but geographically and limnologically diverse training sets, using the European Diatom Database Initiative (EDDI) database. The relationships between water chemistry and diatom distributions were explored using canonical correspondence analysis (CCA) and partial CCA. Variance partitioning indicated that conductivity accounted for a significant and independent portion of this variation. A transfer function was developed for conductivity (r jack 2 = 0.74). Prediction errors, estimated using jack-knifing, are low for the conductivity model (0.256 log 10 units). The resulting model was applied to a sedimentary sequence from Lake Kasenda, western Uganda. Comparison of conductivity reconstructions using the Ugandan crater lake training set and the East Africa training set (EDDI) highlighted a number of differences in the optima of key diatom taxa, which lead to differences in reconstructed values and could lead to misinterpretation of the fossil record. This study highlights issues of how far transfer functions based on continental-scale lake datasets such as the EDDI pan-African models should be used and the benefits that may be obtained from regional training sets. © 2012 Springer Science+Business Media B.V.
Rainfall-driven Episodic Flood Events : Are they a major factor in moulding New South Wales arid land vegetation patterns?
- Authors: Florentine, Singarayer , Westbrooke, Martin
- Date: 2005
- Type: Text , Journal article
- Relation: Australian Geographer Vol. 36, no. 2 (2005), p. 171-181
- Full Text:
- Reviewed:
- Description: Episodic high rainfall has been proposed as an important factor in perennial species recruitment but flooding based on rainfall at a distance from the site has received little attention. Although such flood events in arid Australia are rare, studies of the ephemeral Olary Creek indicate that occasional floods can also have a high impact on the vegetation and landscape. During February 1997, a high-rainfall event caused flooding in the Olary Creek. One branch of the creek created a terminal lake within mallee vegetation on Nagaela Station in far-western New South Wales. The flood path of Olary Creek and this terminal lake allow study of the importance of rainfall-driven flood events in shaping vegetation in arid environments. This paper reports (i) the response of arid land plant species to high-rainfall-driven episodic flood events and (ii) how grazing pressure from native and introduced herbivores can impact on native species response. A systematic study was conducted to understand the botanical composition in flooded and control areas based on 25 m2 fenced and unfenced plots subjected to flooding and nonflooding. For 6 years following flooding, species richness in the flooded area was twice that of unflooded areas. In particular, 27 native species from 13 families were recorded both in the enclosed and open plots located in the flooded area. Over the study period nine species: Brachyscome ciliaris, Helichrysum leucopsidium, Vittadinia cuneata, Casuarina pauper, Maireana sedifolia, Salsola kali, Sclerolaena obliquicuspis, Eremophila sturtii and Eucalyptus foecunda germinated only in the flooded enclosed plots. Further, 11 exotic species from five families were recorded in the flooded (both enclosed and open) plots over the study period. Knowledge gained from this study will contribute to management strategies for arid land vegetation.
- Description: C1
- Description: 2003001067
Expressions of climate perturbations in western ugandan crater lake sediment records during the last 1000 years
- Authors: Mills, Keely , Ryves, David , Anderson, Nicholas , Bryant, Charlotte , Tyler, J.J.
- Date: 2014
- Type: Text , Journal article
- Relation: Climate of the Past Vol. 10, no. 4 (2014), p. 1581-1601
- Full Text:
- Reviewed:
- Description: Equatorial East Africa has a complex regional patchwork of climate regimes, sensitive to climate fluctuations over a variety of temporal and spatial scales during the late Holocene. Understanding how these changes are recorded in and interpreted from biological and geochemical proxies in lake sedimentary records remains a key challenge to answering fundamental questions regarding the nature, spatial extent and synchroneity of climatic changes seen in East African palaeo-records. Using a paired lake approach, where neighbouring lakes share the same geology, climate and landscape, it might be expected that the systems will respond similarly to external climate forcing. Sediment cores from two crater lakes in western Uganda spanning the last ∼1000 years were examined to assess diatom community responses to late Holocene climate and environmental changes, and to test responses to multiple drivers using redundancy analysis (RDA). These archives provide annual to sub-decadal records of environmental change
Flood vulnerabillity analysis in coastal zones : a comparative analysis across five asia-pacific countries
- Authors: Wright, Wendy , Dutta, Dushmanta , Rayment, Philip
- Date: 2010
- Type: Text , Conference paper
- Relation: Proceedings of the International Symposium on Coastal Zones and Climate Change: Assessing the Impacts and Developing Adaptation Strategies
- Full Text: false
- Reviewed:
Linking soil moisture balance and source-responsive models to estimate diffuse and preferential components of groundwater recharge
- Authors: Cuthbert, M. , Mackay, Rae , Nimmo, J.
- Date: 2012
- Type: Text , Journal article
- Relation: Hydrology and Earth System Sciences Discussions Vol. 9, no. 7 (2012), p. 8455-8492
- Full Text:
- Reviewed:
- Description: Results are presented of a detailed study into the vadose zone and shallow water table hydrodynamics of a field site in Shropshire, UK. A conceptual model is developed and tested using a range of numerical models, including a modified soil moisture balance model (SMBM) for estimating groundwater recharge in the presence of both diffuse and preferential flow components. Tensiometry reveals that the loamy sand topsoil wets up via macropore flow and subsequent redistribution of moisture into the soil matrix. Recharge does not occur until near-positive pressures are achieved at the top of the sandy glaciofluvial outwash material that underlies the topsoil, about 1 m above the water table. Once this occurs, very rapid water table rises follow. This threshold behaviour is attributed to the vertical discontinuity in the macropore system due to seasonal ploughing of the topsoil, and a lower permeability plough/iron pan restricting matrix flow between the topsoil and the lower outwash deposits. Although the wetting process in the topsoil is complex, a SMBM is shown to be effective in predicting the initiation of preferential flow from the base of the topsoil into the lower outwash horizon. The rapidity of the response at the water table and a water table rise during the summer period while flow gradients in the unsaturated profile were upward suggest that preferential flow is also occurring within the outwash deposits below the topsoil. A variation of the source-responsive model proposed by Nimmo (2010) is shown to reproduce the observed water table dynamics well in the lower outwash horizon when linked to a SMBM that quantifies the potential recharge from the topsoil. The results reveal new insights into preferential flow processes in cultivated soils and provide a useful and practical approach to accounting for preferential flow in studies of groundwater recharge estimation.
Diatom and stable isotope record of Late Holecene lake ontogeny at Indrepollen, Lofoten, NW Norway: a response to isostacy and neoglacial cooling
- Authors: Mills, Keely , Mackay, Anson , Bradley, Raymond , Finney, Bruce
- Date: 2009
- Type: Text , Journal article
- Relation: The Holocene Vol. 19, no. 3 (2009), p. 261-271
- Full Text:
- Reviewed:
- Description: Borg Indrepollen is a coastal lake on the island of Vestvågøy, Lofoten, NW Norway. A sedimentary sequence spanning the last 4500 cal. yr BP was analysed for diatom, C/N and stable isotopes (
- Description: C1
Automatic extraction of building roofs using LIDAR data and multispectral imagery
- Authors: Awrangjeb, Mohammad , Zhang, Chunsun , Fraser, Clive
- Date: 2013
- Type: Text , Journal article
- Relation: ISPRS Journal of Photogrammetry and Remote Sensing Vol. 83, no. (2013), p. 1-18
- Full Text: false
- Reviewed:
- Description: Automatic 3D extraction of building roofs from remotely sensed data is important for many applications including city modelling. This paper proposes a new method for automatic 3D roof extraction through an effective integration of LIDAR (Light Detection And Ranging) data and multispectral orthoimagery. Using the ground height from a DEM (Digital Elevation Model), the raw LIDAR points are separated into two groups. The first group contains the ground points that are exploited to constitute a ‘ground mask’. The second group contains the non-ground points which are segmented using an innovative image line guided segmentation technique to extract the roof planes. The image lines are extracted from the grey-scale version of the orthoimage and then classified into several classes such as ‘ground’, ‘tree’, ‘roof edge’ and ‘roof ridge’ using the ground mask and colour and texture information from the orthoimagery. During segmentation of the non-ground LIDAR points, the lines from the latter two classes are used as baselines to locate the nearby LIDAR points of the neighbouring planes. For each plane a robust seed region is thereby defined using the nearby non-ground LIDAR points of a baseline and this region is iteratively grown to extract the complete roof plane. Finally, a newly proposed rule-based procedure is applied to remove planes constructed on trees. Experimental results show that the proposed method can successfully remove vegetation and so offers high extraction rates.
Sea level trends at locations of the United States with more than 100 years of recording
- Authors: Parker, Albert
- Date: 2013
- Type: Text , Journal article
- Relation: Natural Hazards Vol. 65, no. 1 (2013), p. 1011-1021
- Full Text: false
- Reviewed:
- Description: The paper presents the sea level rises (SLR) computed for the United States tide gauges with more than 100 years of recording. It is shown that the monthly sea levels oscillate about an almost linear longer-term trend with important multidecadal periodicities. The SLR time history is computed by linear fitting of 20, 30 and 60 years of data up to a given time (SLR20, SLR30 and SLR60) and is compared to the value obtained by considering all the data. It is shown that SLR60 has smaller oscillations, while SLR20 and SLR30 have much larger and frequent fluctuations. While SLR60 may oscillate ±10-30 % about the latest longer-term value, SLR30 may fluctuate ±50-100 % and SLR20 ± 100-200 %. The values obtained by considering all the data with a minimum of 60 years (SLRA) also fluctuate ±5-15 % about the latest longer-term value. This indicates the need to use the time history of SLR60 or SLRA when the record is longer than 60 years to assess the accelerating trend. For all the stations, the sea levels regularly oscillate about the linear longer-term trend, and if acceleration has to be computed, this is eventually negative, that is, the SLR is reducing. © 2012 Springer Science+Business Media B.V.
- Description: 2003010587
Large versus small wood in streams : the effect of wood dimension on macroinvertebrate communities
- Authors: Lester, Rebecca , Wright, Wendy , Jones-Lennon, Michelle , Rayment, Philip
- Date: 2009
- Type: Text , Journal article
- Relation: Fundamental and Applied Limnology Vol. 174, no. 4 (2009), p. 339-351
- Full Text: false
- Reviewed:
- Description: Conventionally, most research and restoration involving in-stream wood focuses on large wood (>0.1 m diameter), excluding any smaller pieces. However, this may neglect a major component of in-stream habitat, as small wood can constitute the majority of pieces, particularly in small streams. The ecological benefit of large wood is well established, but corresponding benefits associated with small wood (0.05-0.1 m diameter) have not been demonstrated. To test the effect of wood dimension on macroinvertebrate community composition, we compared the fauna occupying large wood habitats with that occupying small wood at eight streams in south-eastern Australia. The relationships between wood dimensions and its macroinvertebrate fauna were complex. Community composition did not vary with wood dimension, and no significant correlations were found between other macroinvertebrate attributes (including family richness and evenness) and wood dimension, including diameter. However, analysis of covariance suggested that large wood supported a greater diversity and abundance of macroinvertebrates, indicating that the method of analysis could influence the result. Adjustment for differences in sample dimension using rarefaction determined that these findings were likely to be a result of the surface area and volumes sampled varying with the dimension of the wood. Per unit surface area, and per unit volume, small wood supported a similar number of families to large wood. Thus we conclude that, relative to the available surface area, small and large wood can be equivalent in their contribution to the available habitat in a stream. Therefore, the potential value of small wood as a habitat resource warrants its explicit consideration for inclusion in ecological and rehabilitation studies.
Hydrologic impact of climate change on Murray–Hotham catchment of Western Australia : A projection of rainfall–runoff for future water resources planning
- Authors: Islam, Syed , Bari, Mohammed , Anwar, Faisal
- Date: 2014
- Type: Text , Journal article
- Relation: Hydrology and Earth System Sciences Vol. 18, no. 9 (2014), p. 3591-3614
- Full Text:
- Reviewed:
- Description: Reduction of rainfall and runoff in recent years across southwest Western Australia (SWWA) has attracted attention to the climate change impact on water resources and water availability in this region. In this paper, the hydrologic impact of climate change on the Murray–Hotham catchment in SWWA has been investigated using a multi-model ensemble approach through projection of rainfall and runoff for the periods mid (2046–2065) and late (2081–2100) this century. The Land Use Change Incorporated Catchment (LUCICAT) model was used for hydrologic modelling. Model calibration was performed using (5 km) grid rainfall data from the Australian Water Availability Project (AWAP). Downscaled and bias-corrected rainfall data from 11 general circulation models (GCMs) for Intergovernmental Panel on Climate Change (IPCC) emission scenarios A2 and B1 was used in LUCICAT model to derive rainfall and runoff scenarios for 2046–2065 (mid this century) and 2081–2100 (late this century). The results of the climate scenarios were compared with observed past (1961–1980) climate. The mean annual rainfall averaged over the catchment during recent time (1981–2000) was reduced by 2.3%with respect to the observed past (1961–1980) and the resulting runoff reduction was found to be 14 %. Compared to the past, the mean annual rainfall reductions, averaged over 11 ensembles and over the period for the catchment for A2 scenario are 13.6 and 23.6% for mid and late this century respectively while the corresponding runoff reductions are 36 and 74%. For B1 scenario, the rainfall reductions were 11.9 and 11.6% for mid and late this century and the corresponding runoff reductions were 31 and 38%. Spatial distribution of rainfall and runoff changes showed that the rate of changes were higher in high rainfall areas compared to low rainfall areas.Temporal distribution of rainfall and runoff indicate that high rainfall events in the catchment reduced significantly and further reductions are projected, resulting in significant runoff reductions. A catchment scenario map has been developed by plotting decadal runoff reduction against corresponding rainfall reduction at four gauging stations for the observed and projected periods. This could be useful for planning future water resources in the catchment. Projection of rainfall and runoff made based on the GCMs varied significantly for the time periods and emission scenarios. Hence, the considerable uncertainty involved in this study though ensemble mean was used to explain the findings.
Assessing the impact of drought and forestry on streamflows in south-eastern Australia using a physically based hydrological model
- Authors: Brown, Stuart , Versace, Vincent , Lester, Rebecca , Todd Walter, M.
- Date: 2015
- Type: Text , Journal article
- Relation: Environmental Earth Sciences Vol. 74, no. 7 (2015), p. 6047-6063
- Full Text: false
- Reviewed:
- Description: An increase in plantation forestry has been linked to a reduction in streamflows in some catchments. Quantifying the relative contribution of this land-use change on streamflows can be complex when those changes occur during weather extremes such as drought. In this study, the Soil and Water Assessment Tool (SWAT) model was applied to two sub-catchments in south-eastern Australia which have seen the introduction and establishment of plantation land use in the past 15 years, coinciding with severe drought (1997–2009). The models were both manually and auto-calibrated and produced very good fits to observed streamflow data during both calibration (1980–1991) and validation (1992–2009) periods. Sensitivity analyses indicated that the models were most sensitive to soil and groundwater parameterisation. Analysis of drought conditions on streamflows showed significant declines from long-term average streamflows, while assessment of baseflow contributions by the models indicated a mix of over- and underestimation depending on catchment and season. The modelled introduction of plantation forestry did not significantly change streamflows for a scenario which did not include the land-use change, suggesting that the modelled land-use change in the catchments was not sufficiently extensive to have an impact on streamflows despite simulating actual rates of change. The SWAT models developed by this study will be invaluable as a basis for future use in regional climate-change studies and for the assessment of land management and land-use change impact on streamflows. © 2015, Springer-Verlag Berlin Heidelberg.
Liberation of acidity and arsenic from schwertmannite : Effect of fulvic acid
- Authors: Vithana, Chamindra , Sullivan, Leigh , Burton, Edward , Bush, Richard
- Date: 2014
- Type: Text , Journal article
- Relation: Chemical Geology Vol. 372, no. (2014), p. 1-11
- Full Text: false
- Reviewed:
- Description: Schwertmannite is one of the major components that produces acidity in acid mine drainage (AMD) and acid sulfate soils (ASS) and is also known to be an effective scavenger of Arsenic (As) in such environments. Fulvic acid (FA) is an active component of natural organic matter (NOM) and is known to interact strongly with both schwertmannite and As. Two main environmental hazards related to schwertmannite are acidity liberation and potential re-mobilization of adsorbed or co-precipitated As upon hydrolysis. This study focused on understanding the behaviour of As-substituted schwertmannite with regard to the potential of acidity liberation, the effect of FA on acidity liberation from both pure and As-substituted synthetic schwertmannites, and the effect of FA on arsenic mobilization from As-substituted synthetic schwertmannite. This was investigated by means of short-term (48. h) titrations. The liberation of acidity from As-substituted schwertmannite and the effect of FA were examined at two pH values (i.e. 4.5 and 6.5) typical for ASS environments.As-substituted schwertmannite liberated a greater amount of acidity in comparison to pure schwertmannite at both pHs. Concentration of FA and pH each showed a strong influence on the liberation of acidity from both pure and As-schwertmannite. At the acidic pH (4.5), FA inhibited acidity liberation from schwertmannite. At the near neutral pH of 6.5, the concentration of FA played a critical role in affecting the liberation of acidity from schwertmannite. The initial liberation of acidity was enhanced from pure schwertmannite at pH6.5 by low FA concentration (1mgL-1) and from As-schwertmannite by both low (1mgL-1) and moderate (10mgL-1) FA concentrations. Interestingly, higher FA concentrations (25mgL-1) inhibited acidity liberation from both types of schwertmannite in comparison to the control (pure/As-schwertmannite titrated without added FA). FA enhanced the liberation of As from the As-schwertmannite at both pHs under oxidising conditions and the rate of As liberation was greater at the near neutral pH. The present study provides new insights on the effect of As-substitution on acidity liberation from schwertmannite and the role of FA on: a) liberation of acidity, and b) As mobilization, from schwertmannite. © 2014.
Mobility of arsenic and selected metals during re-flooding of iron- and organic-rich acid-sulfate soil
- Authors: Burton, Edward , Bush, Richard , Sullivan, Leigh , Johnston, Scott , Hocking, Rosalie
- Date: 2008
- Type: Text , Journal article
- Relation: Chemical Geology Vol. 253, no. 1-2 (2008), p. 64-73
- Full Text: false
- Reviewed:
- Description: The drainage-induced oxidation of iron-sulfide minerals in acid-sulfate soils has adversely affected large areas of coastal floodplains. Re-flooding of these soils, via the re-establishment of more natural drainage regimes, is a potential remediation approach. Here we describe the mobility of Al, As, Fe, Mn, Ni and Zn during controlled re-flooding of an Fe- and organic-rich acid-sulfate soil material. Soil re-flooding caused the onset of microbially-mediated Fe(III)-reduction, which raised the pH of the initially acidic (pH 3.4) soil to pH 6.0 to 6.5, thereby immobilizing Al. The process of Fe(III)-reduction released high concentrations of FeII and was associated with significant mobilization of As. During the early stages of re-flooding, FeII mobility was controlled by dissolution of schwertmannite (Fe8O8(OH)6SO4) with an ion activity product (IAP) of 1019 ± 2. The mobility of FeII was subsequently controlled by the precipitation of siderite (FeCO3) with an IAP spanning 10- 10 to 10- 7.5. The formation of acid-volatile sulfide (AVS), as a product of SO4-reduction, further retarded the mobility of FeII. Interactions with AVS also strongly immobilized Mn, Ni and Zn, yet had little effect on As which remained relatively mobile in the re-flooded soil. This study shows that the mobilization of As and Fe during soil re-flooding should be considered when planning remediation approaches for acid-sulfate soils. © 2008 Elsevier B.V. All rights reserved.