scholarly journals Response of the Snowy River Estuary to two environmental flows

2015 ◽  
Vol 127 (2) ◽  
pp. 28
Author(s):  
Errol J. McLean ◽  
Jon B. Hinwood
Keyword(s):  
Fresh Water ◽  
Peak Flow ◽  
Environmental Flows ◽  
River Estuary ◽  
Environmental Flow ◽  
River Channel ◽  
Salinity Gradients ◽  
Tasman Sea ◽  
Eastern Australia ◽  
Major River

The Snowy River is a major river in south-eastern Australia, discharging to the Tasman Sea via a barrier estuary, with its entrance constricted by marine sands. Since the construction of the Snowy Mountains Scheme, river flows have not been sufficient to maintain the river channel. A program of environmental flow releases (EFR) is returning water to the river to restore the fluvial reaches and is now trialling flow regimes that may also benefit the estuarine reaches. This paper documents the response of the estuarine segments of the Snowy River to two EFRs; the release in 2010 was designed to scour the upper reaches of the Snowy River while the larger 2011 release was intended to extend the scouring downstream. For each release, the effects on the entrance morphology, tides and salinity through the flow peak and recovery are described. Each EFR caused minor increases in depth and very minor longshore movement of the entrance channel, although each EFR had been preceded by a larger fresh flow that would have scoured the channels. The small increase in fresh water inflow in the 2010 EFR pushed salinity contours seawards and steepened vertical salinity gradients. The larger inflow in the 2011 EFR purged the upper estuary of saltwater. After the peak flow, salinity recovery was rapid in the principal estuarine channels but took weeks where poorly connected wetlands could store fresh flood waters. Critical flows for scouring the entrance and purging salinity are estimated.

scholarly journals Environmental flow assessments in estuaries related to preference of phytoplankton

2014 ◽  
Vol 18 (5) ◽  
pp. 1785-1791 ◽  
Author(s):  
Z. F. Yang ◽  
T. Sun ◽  
R. Zhao
Keyword(s):  
Environmental Factors ◽  
River Flow ◽  
Yellow River ◽  
Environmental Flows ◽  
River Estuary ◽  
High Amplitude ◽  
Environmental Flow ◽  
Negative Effects ◽  
Flood Pulses ◽  
Complex Relationships

Abstract. An approach to assess estuarine environmental flow based on phytoplankton preference, including the complex relationships between hydrological modifications and ecosystem biomass, was developed in this study. We initially established a relationship between biomass requirements for primary and higher nutritional level organisms based on the ecosystem nutritional energy flow principles. Subsequently, diagnostic pigments were employed to represent phytoplankton community biomass, which indicated competition between two groups of phytoplankton in the biochemistry process. Considering empirical relationships between diagnostic pigments and critical environmental factors, biomass responses to river discharge were established by simulating distributions of critical environmental factors under action of river discharges and tide currents. Consequently, environmental flows were recommended for different fish biomass requirements. We used the Yellow River estuary as a case study; and May and June were identified as critical months for maintaining environmental flow. Temporal variation in natural river flow dynamics, which was used as a proxy for environmental flow, should be carefully examined in artificial hydrological regulation strategies, particularly during high-amplitude flood pulses, which might result in negative effects on phytoplankton groups, and subsequently higher aquatic species biomass.

Estimation of Environmental Flow Requirements in the Zhangweixin River Estuary, China

2012 ◽  
Vol 518-523 ◽  
pp. 4341-4345
Author(s):  
Tao Peng ◽  
Xiao Hong Chen ◽  
Gao Xu Wang
Keyword(s):  
Environmental Flows ◽  
River Estuary ◽  
Environmental Flow ◽  
Larval Period ◽  
Water Quantity ◽  
Freshwater Inflows ◽  
The Relationship ◽  
Different Levels ◽  
Migratory Fishes

Environmental flow requirements (EFRs for short), which considered the requirements for protection of migratory fishes habitat in spawning and larval period, were analyzed in this paper for the Zhangweixin River Estuary (ZRE for short), China. Based on the different levels of salinity objectives and the relationship between salinity and the freshwater inflows, the EFRs for the ZRE were determined. Annual EFRs should be 2.1 × 108 and 9.9 × 108 m3 for the minimum and appropriate levels objectives in the ZRE, respectively. The minimum and appropriate EFRs can be satisfied by 38% and 11% of year’s annual freshwater inflows in the ZRE during 1956-2010, respectively. Moreover, with the freshwater inflows decreasing, the monthly EFRs for the ZRE cannot be fulfilled in longer period of the year. The seasonal discrepancy between the water quantity requirement to meet ecological goals and the practical freshwater inflows was outstanding during longer periods of the 2000s. The periods from March to September should be considered as the critical seasons to maintain the minimum environmental flows in the ZRE.

scholarly journals Assessment of the Multi-Objective Reservoir Operation for Maintaining the Turbidity Maximum Zone in the Yangtze River Estuary

2018 ◽  
Vol 15 (10) ◽  
pp. 2118 ◽  
Author(s):  
Yang Yu ◽  
Peifang Wang ◽  
Chao Wang ◽  
Xun Wang ◽  
Bin Hu
Keyword(s):  
Reservoir Operation ◽  
Yangtze River ◽  
Environmental Flows ◽  
River Estuary ◽  
Yangtze River Estuary ◽  
The Yangtze River ◽  
Operation Model ◽  
Hydropower Generation ◽  
Quantitative Correlation ◽  
The Yangtze River Estuary

The construction of multifunction reservoirs is important for flood control, agriculture irrigation, navigation, and hydropower generation, but dam construction will inevitably affect the downstream flow and sediment regimes, which can cause some environmental and ecological consequences. Therefore, this paper aims to propose a framework for assessing the multiobjective reservoir operation model based on environmental flows for sustaining the suspended sediment concentration (SSC) requirements in the turbidity maximum zone (TMZ). The Yangtze River Estuary was used as a case study. Through using an analytical model, a quantitative correlation between SSC and water flow rate was established. Then, the quantitative correlation and the SSC requirements were applied to determine the environmental flows for the estuarine TMZ. Subsequently, a multiobjective reservoir operation model was developed for the Three Gorges Reservoir (TGR), and an improved nondominated sorting genetic algorithm III based on elimination operator was applied to the model. An uncertainty analysis and a comparative analysis were used to assess the model’s performance. The results showed that the proposed multiobjective reservoir operation model can reduce ecological deficiency under wet, normal, and dry years by 33.65%, 35.95%, and 20.98%, with the corresponding hydropower generation output lost by 3.37%, 3.88%, and 2.95%, respectively. Finally, we discussed ecological satiety rates under optimized and practical operation of the TGR in wet, normal, and dry years. It indicated that the multiobjective-optimized runoff performs better at maintaining the TMZ in the Yangtze River Estuary than practical runoff. More importantly, the results can offer guidance for the management of the TGR to improve the comprehensive development and protection of the estuarine ecological environment.

scholarly journals Impact of flow variability and sediment characteristics on channel width evolution

2018 ◽  
Vol 40 ◽  
pp. 05044
Author(s):  
Andrés Vargas-Luna ◽  
Alessandra Crosato ◽  
Protogene Byishimo ◽  
Wim Uijttewaal
Keyword(s):  
Grain Size ◽  
Peak Flow ◽  
River Channel ◽  
Channel Width ◽  
River Morphology ◽  
Channel Formation ◽  
Sediment Characteristics ◽  
Alluvial Rivers ◽  
Water Flows ◽  
Streamflow Variability

Alluvial rivers are shaped by sequences of water flows excavating their channels. Observations show that besides the magnitude, also the frequency and duration of streamflow oscillations might be important for the river channel formation. In addition, the river morphology appears influenced also by both size and degree of uniformity of the sediment. Nevertheless, many morphodynamic studies still represent the flow regime with a single value of the discharge, often corresponding to the bankfull condition, and the sediment with its median grain size. This work investigates the effects of streamflow variability and sediment characteristics on channel width formation, analysing the evolution of experimental streams with different sediments and discharge hydrographs. Results show that the formative condition of the channel width is not the geometric bankfull flow but a rather frequent peak flow. Remarkably different channel configurations arise from different sediment characteristics in the laboratory, where sediment non-uniformity produces more stable banks.

Mid Pleistocene arid shift in southern Australia, dated by magnetostratigraphy

Soil Research ◽  
2001 ◽  
Vol 39 (1) ◽  
pp. 89 ◽  
Author(s):  
Brad Pillans ◽  
Robert Bourman
Keyword(s):  
Marked Change ◽  
Source Area ◽  
Pronounced Change ◽  
Sea Levels ◽  
Leeuwin Current ◽  
Polarity Transition ◽  
Tasman Sea ◽  
Eastern Australia ◽  
Regional Climates ◽  
Regional Rainfall

In coastal sections at Hallett Cove and Sellicks Beach, south of Adelaide, and at Redbanks section on Kangaroo Island, the Brunhes/Matuyama polarity transition (780 ka) is identified in the strongly oxide-mottled Ochre Cove Formation. At all 3 sections, the Ochre Cove Formation is overlain by a calcareous grey-green aeolian clay, called Ngaltinga Clay, which in turn is overlain by calcareous sediments of the Taringa and Christies Beach Formations. The marked change from an oxide-dominated weathering regime to a carbonate-dominated weathering regime, estimated to have occurred at about 500–600 ka, is interpreted as a major arid shift in regional climates. Similar arid shifts are known from Lake Bungunnia in the Murray Basin and Lake Lefroy in southern Western Australia, where changes from lacustrine clays to evaporites and dune sediments are estimated to have occurred between 400 and 700 ka, and about 500 ka, respectively. An increase in aeolian dust accession in south-eastern Australia, consistent with increased aridity in the interior source area, occurred after 780 ka, and was probably coeval with increased dust input to Tasman Sea sediments since 350 ka. Between 600 and 900 ka, oxygen isotope fluctuations in deep-sea cores showed a pronounced change in frequency, from a 40 ka (obliquity dominated) to a 100 ka (eccentricity dominated) pattern. At the same time, glacial-interglacial amplitudes increased, with a marked enrichment of glacial d18O values consistent with larger continental based ice-sheets. Colder global temperatures, and lower sea levels during glacials, may have played a part in the mid Pleistocene arid shift recorded in southern Australia. Associated variations in the strength of the warm Leeuwin Current may also have affected regional rainfall patterns in southern Australia.

Application of Methodologies for Environmental Flow Determination in an Andean and a Mediterranean Basin

2013 ◽  
pp. 296-314
Author(s):  
Yesid Carvajal-Escobar ◽  
Ziad Mimi ◽  
Saed Khayat ◽  
Saleh Sulieman ◽  
Wilson Garces ◽  
...  
Keyword(s):  
Mediterranean Basin ◽  
Significant Variation ◽  
Environmental Flows ◽  
Environmental Flow ◽  
Base Flow ◽  
Point Sources ◽  
Local Context ◽  
Mediterranean River ◽  
Hydrological Indices ◽  
Hydrological Parameter

The demand for sustainable water management has promoted the development of methodologies for estimating environmental flows (EF). In this paper, the EF in an Andean river (Pance, Colombia) for conservation and a Mediterranean river (Wadi-Zomar, Palestine) for restoration purposes is made. Different methodologies are applied given the objectives for each river. The authors used hydrological indices proposed for watersheds with different water regimes and adaptations and validations were made to the local context. These methods allow for estimating the EF at various points in the river and the assessment of disruption scenarios for decision-making. In the Wadi Zomar River, three sampling points were selected. The water samples were then examined for the presence of pathogens. No one indicator or simple hydrological parameter is entirely suitable for all environmental systems and pathogens. In the base flow conditions, the amount of pollutant load varied temporally according to the amount of load from point sources along the Wadi, and spatially with distance from the same sources. Significant variation was observed in response to the hydrological behavior of the catchment. The assessment for the water quality in the Zomar reflects a potentially serious threat to the environment. The results emphasize the need for regulating the seepage effluent from industries and sewage system along the stream.

Environmental Flows Legislation and Regulations in Foreign Countries and the Enlightenment to China

2013 ◽  
Vol 295-298 ◽  
pp. 2181-2186
Author(s):  
Chang Chun Chen ◽  
La Chun Wang ◽  
Xue Zhang Cao ◽  
Jie Song
Keyword(s):  
Water Demand ◽  
Aquatic Ecosystems ◽  
Environmental Flows ◽  
Environmental Flow ◽  
International Agreement ◽  
The Enlightenment ◽  
Foreign Countries ◽  
The World ◽  
Key Factor ◽  
Legislative Proposals

Environmental flow is a key factor to protect river ecological system, however, there is no international agreement concerned with environmental flows exclusively so far. This paper demonstrated the importance and urgency of environment water demand in the world and presented summary and analysis of environmental flows legislation and regulations. Europe and other countries have been investigated and compared systematically. At last, specialized legislative proposals were provided for protection of aquatic ecosystems and their environment in China.

FISSION TRACK THERMOCHRONOLOGY: APPLICATION TO CONTINENTAL RIFTING OF SOUTH-EASTERN AUSTRALIA

1991 ◽  
Vol 31 (1) ◽  
pp. 131 ◽  
Author(s):  
T. A. Dumitru ◽  
K. C. Hill ◽  
D. A. Coyle ◽  
I. R. Duddy ◽  
D. A. Foster ◽  
...  
Keyword(s):  
Thermal History ◽  
Fission Track ◽  
Apatite Fission Track ◽  
South Eastern ◽  
Tasman Sea ◽  
Eastern Australia ◽  
Uplift And Erosion ◽  
Track Analysis ◽  
Plate Type ◽  
South Eastern Australia

Over the last five to ten years, apatite fission track analysis has developed into a sophisticated technique for studying the low-temperature thermal history of rocks. It has particular utility in oil exploration because its temperature range of sensitivity, about 20° to 125°C, overlaps the oil generation window. Whereas older fission track thermal history approaches relied solely on the sample fission track age, the new interpretive approaches use sample age, single grain age and track length data. They also emphasise the analysis of systematic variations in data patterns in sequences of samples, such as samples from various depths in a well. Laboratory study of the thermal annealing of fission tracks and compilation of fission track data from geological case studies has greatly improved our understanding of apatite fission track systematics, allowing considerably more detailed interpretations of thermal histories.Application of apatite fission track analysis to the rifted continental margins of south-eastern Australia shows that rifting and separation of Australia from Antarctica and the Lord Howe Rise were accompanied by at least 1.5-3 km of uplift and erosion along the Tasman Sea and Bass Strait coasts. Uplift and erosion were much less 100 km or so inland. This shows that the uplift of the south-eastern Australian margins was caused by the continental rifting process, the same process that initiated major subsidence in the sedimentary basins in Bass Strait. The consistent fission track data patterns around south-eastern Australia suggest a generally similar tectonic setting for the Tasman Sea and Bass Strait parts of the margin. Lister et al. (in press) propose that the Tasman part of the margin is an upper plate type of margin that formed above a west-dipping detachment zone. The fission track data suggest that the Bass Strait part of the margin may also be of upper plate type.

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