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In their recent paper, Williams et al. (2022) evaluated salinity management in the Murray-Darling Basin (MDB) as 'unsustainable', and a risk to water availability and quality in the Basin. However, this evaluation was weakened first by a failure to analyse the Basin salinity strategies of the last thirty-five years, noting that these have led to Basin salinity target being met since 2010; and second to not providing Basin-specific data to support their evaluation. Contrary to Williams et al. comments, existing evidence indicates that infrastructure intended to improve water use efficiency (e.g. salt leaching, salt disposal basins) will generally reduce stream salinity. The requirement for a leaching efficiency means that there is a lower limit to water use efficiency improvements, but this is unlikely itself to be a major risk. We agree that the changes that have occurred over the last twenty years would warrant a review of salt storage options in the MDB that better matches future needs. [ABSTRACT FROM AUTHOR]

The Shatt Al-Arab estuary is the lifeline of the Basrah city, as it is the source of water for various uses of irrigation, industry, agriculture and human use, in addition to being the navigational passage towards the Arabian Gulf throughout history. Nowadays, the estuary suffers from the deterioration of its water quality due to the increase in salinity values as a result of the intrusion of salinity from the Arabian Gulf due to the lack of freshwater flows from the Tigris and Euphrates rivers. To reduce the risks of water quality deterioration and the lack of natural solutions represented in the provision of freshwater, the idea of building an artificial structure to narrow the channel came to give the ability to resist the impact of the tide and the intrusion of marine salinity. Two hypothetical sites were chosen to build the structure: i.e. in Dweeb and Faw sites, to test the feasibility of this artificial estuary structure. A one-dimensional mathematical model was adopted, which is the Mike 11 software package. The model was run according to a set of scenarios using the critical water discharge values of 10 and 20 m3/s. The results showed through simulation of the model for a period of six months that the structure is useful on improving the water quality by reducing salinity in the river, in addition, there is a delay in the time of arrival of the intrusion of salts. [ABSTRACT FROM AUTHOR]

Salinity is a classic problem in water quality management since it is directly associated with low water quality indices. Debate continues about selecting the best model for water quality forecasting, it remains a major challenge and causes much uncertainty. Accordingly, identifying the optimal modelling that can capture the salinity behaviour is becoming a common trend in recent water quality research. This study applies novel combined techniques, including data pre- processing and artificial neural network (ANN) optimised with constriction coeffi- cient-based particle swarm optimisation and chaotic gravitational search algorithm (CPSOCGSA) to forecast monthly salinity data. Historical monthly total dissolved solids (TDS) and electrical conductivity (EC) data of the Euphrates River at Al- Musayyab, Babylon, and climatic factors from 2010 to 2019 were used to build and validate the methodology. Additionally, for more validation, the CPSOCGSA-ANN was compared with the slime mould algorithm (SMA-ANN), particle swarm optimisation (PSO-ANN) and multi-verse optimiser (MVO-ANN). The results reveal that the pre-processing data approaches improved data quality and selected the best predictors’ scenario. The CPSOCGSA-ANN algorithm is the best based on several statistical criteria. The proposed methodology accurately simulated the TDS and EC time series based on R² = 0.99 and 0.97, respectively, and SI = 0.003 for both parameters. [ABSTRACT FROM AUTHOR]

The aim is to study the feasibility of applying a new type of sustainable energy known as osmosis power (blue energy), which is a renewable source of electricity. This is available in the city of Basra at the confluence of the water of its six rivers with the Shatt al-Arab's waters. Therefore, this research will focus on the technical application of osmosis energy in the Basra's rivers (Specifically, membrane-based techniques), and test it by using simulation model, which will provide with the characteristics of the flow of each river, and the electrical energy that can be produced at the estuaries. The research concluded that if the concentration of salinity in these rivers ranges between (8-64 mmoh/cm), it is able to generate an osmosis pressure capable of rotating turbines in some parts of the river, and producing electric energy ranging from (11.92-13.08 kwh/m3). [ABSTRACT FROM AUTHOR]

Traditional monitoring methods often ignore the vegetation information, which has significantly indirect influence on the process of soil salinization. In this study, the vegetation indices-salinity indices (VI-SI) feature space was utilized to improve the inversion accuracy of soil salinity, while considering the bare soil and vegetation information. By fully considering the surface vegetation landscape in the Yellow River Delta, twelve VI-SI feature spaces were constructed, and two categories of soil salinization monitoring index were established. The experiment results showed that remote sensing monitoring index based on MSAVI-SI1 had the highest inversion accuracy (coefficient of determination (R2) = 0.912), while that based on the ENDVI-SI4 feature space had the lowest (R2 = 0.664). Therefore, the remote sensing monitoring index derived from MSAVI-SI can greatly improve the dynamic and periodical monitoring of soil salinity in the Yellow River Delta. [ABSTRACT FROM AUTHOR]

Shallow coastal lakes are prone to large fluctuations in physico-chemical variables such as salinity and turbidity. This is now escalating in response to global change. A flood event in March 2014 resulted in a silt plume spreading through part of Lake St Lucia (South Africa). To determine the impact of this event on zooplankton, the Narrows region of St Lucia was sampled on a monthly basis from March to September 2014. For comparative purposes, data from samples collected prior to the flood event were included in the analyses. Analysis of similarity (ANOSIM) revealed dissimilarities in zooplankton community structure among the sampling occasions. The March 2014–May 2014 period was characterized by the highest abundance of freshwater species. Conversely, the abundance of the resident St Lucia copepods Acartiella natalensis and Oithona brevicornis was lowest during this time, and highest in September 2014. The other dominant copepod Pseudodiaptomus stuhlmanni prevailed in March 2014, but declined markedly in April. As of September 2014, P. stuhlmanni had yet to regain its pre-flood densities. The BIOENV procedure, which relates biological and environmental data, revealed that turbidity, salinity and dissolved oxygen were responsible for the observed changes in zooplankton community structure during the study period. Careful management of turbidity and salinity is stressed, as both factors are major drivers of the biota of St Lucia and similar systems worldwide. [ABSTRACT FROM AUTHOR]

We studied the spatial and temporal distribution pattern of three marine mysids (Chlamydopleon dissimile, Metamysidopsis elongata atlantica and Mysidopsis coelhoi) from the Cananeia-Iguape Coastal System, southeast Brazil, in relation to environmental variables and zooplankton abundance. We also analysed mysid reproductive traits, and tested their tolerance to salinity gradients in laboratory experiments. Salinity was identified as a major factor influencing mysid spatial and temporal distribution, selectively limiting their distribution within the estuary. Chlamydopleon dissimile and M. coelhoi were common, but occurred at low abundances throughout the year, whereas the numerically dominant M. elongata atlantica had abundance peaks in spring, when thermohaline conditions were more favourable. Mysid brood size varied interspecifically; the occurrence of juveniles throughout the year indicated that mysids breed continuously in the region. The high biomass of M. elongata atlantica observed in spring confirms the importance of mysids in coastal regions' food webs. [ABSTRACT FROM AUTHOR]

To assess temporal variations in fish assemblages, fish samples were collected on a monthly basis in the surf zone of the Nakdong River Estuary in 2004. Surveys were conducted at two sites during day and night neap tides using a 10-m beach seine. In total, 2397 specimens (8146.0 g) comprising 27 species and 16 families were collected during the study period. The dominant fish species wereMugil cephalus,Plecoglossus altivelis,Favonigobius gymnauchen,Opsariichthys uncirostris amurensis, andHyporhamphus sajori, which accounted for 84.6% of the total number of individuals. The fish sampled were primarily small species or the early juveniles of larger species. The species composition and abundance varied greatly, with a peak in the number of individuals in July (summer) and January (winter), and the peak in biomass during July (summer). The catch rate was low in the spring and autumn months due to the low abundance of the dominant species recorded. A cluster analysis revealed that the fish assemblages were characterized by distinct seasonal groups reflecting the reproductive habits of adult fishes. Fish abundance did not significantly differ between the two sites, although a significant difference in their abundance was detected between day and night, with more fish specimens collected at night than during the day at both sites. The Nakdong River Estuary is an important ecosystem for small and/or juvenile fishes, providing a habitat within the estuary suitable for their development and migration. [ABSTRACT FROM PUBLISHER]

MysidsTenagomysis chiltoniandT. novaezealandiaeare abundant in southern New Zealand estuaries. Size-specific oxygen consumption rates of adult females ofT. chiltoniandT. novaezealandiaewere measured under salinities 0–1, 5, 10, 15, 20, 25, 30 and 33–34 at 5 °C and 20 °C in relation to body size. We predicted that, irrespective of salinity variations, the larger individuals would show lower size-specific oxygen consumption rates than smaller ones. Body size and the changes in salinity were not significantly related to the size-specific oxygen consumption rates ofT. chiltoniandT. novaezealandiae, probably because of the small size range of individuals measured. At 20 °C, size-specific oxygen consumption rates were significantly higher than those at 5 °C forT. novaezealandiae, but not forT. chiltoni. Within the tolerable range of salinity variation, small differences in body size are possibly not important for energetics of adultTenagomysisspp. [ABSTRACT FROM PUBLISHER]

Salt accessions are the major water quality issue of the rivers and streams of the Murray-Darling Basin. The saline Murray Group Aquifer, the salinity of which exceeds 20,000 μS/cm, discharges an estimated 200 t/d of salt into the River Murray in South Australia between Lock 3 and Holder, 40 km downstream. Salinity mitigation works were needed to sustain irrigated agriculture and to maintain the quality of domestic, industrial and urban water supplies. Forty nine wells were drilled to the aquifer between Lock 3 and Holder from late 1989 to August 1990. Pumping of saline groundwater commenced in 1990 to lower the groundwater gradient to the river to zero thus preventing saline water discharging into the river. Telfer and Way estimated that pumping from the aquifer lowered salinity in the river stream by 46.3 μS/cm. Regression analysis of data that restricted it to three years prior tofull pumping commenced and to 3 years after zero gradient was achieved, with sites as categorical variables, estimated a reduction of 58.4±9.4 μS/ cm for flows ≤ 10,000 ML/d resulting in a reduction in salt load of 277 t/d. Regression modelling methodology can be extended to assessments of similar saline groundwater interception schemes. [ABSTRACT FROM AUTHOR]

Vrana Lake in Dalmatia is a karstic kryptodepression connected to the nearby sea through the karstic subsoil and a canal. Due to interactions with the sea, lake water salinity increases greatly during severe dry periods, seriously endangering the ecosystem. Trend analysis (1961–2010) reveals a decrease in precipitation and surface inflow, but an increase in air temperature, and in sea and lake water levels. Lake inflow and water losses are only partially monitored. Average annual inflow from the monitored part of the catchment is 1722 m3 s-1, but total inflow is significantly greater; the average difference between total inflow and cumulative water losses is 3072 m3 s-1. The paper uses modelling to evaluate total inflow into the lake system, taking into consideration projected climate changes/variations till 2100 from the RegCM3 and ALADIN climate models. The analysis indicates marked decrease in discharge values by the end of this century, by as much as 60%. Editor Z.W. Kundzewicz [ABSTRACT FROM AUTHOR]

Long-term (20+ years) water quality datasets for estuaries are rare, especially for smaller systems. Monitoring of salinity, temperature, pH, dissolved oxygen and turbidity has been undertaken since 1991 in the intensively utilised, modified, and managed temporarily open/closed Touw Estuary and its associated three interconnected estuarine lakes, Eilandvlei, Langvlei and Rondevlei, of the Wilderness Lakes System, South Africa, a national park and Ramsar site. Spatial variability of salinity, pH and turbidity was pronounced in the Touw Estuary but largely absent in the lakes. Significant differences in median salinity, pH, dissolved oxygen and turbidity occurred between lakes, with reverse salinity and pH gradients frequently occurring. Seasonal variability in temperature and dissolved oxygen occurred in all waterbodies. Significant long-term declines in salinity have occurred in the more inland lakes, with decreases in turbidity and pH also occurring in some waterbodies. Water chemistry of the Wilderness Lakes is changing from that of an estuarine to a lacustrine system. Both biological and physical features were driving water quality changes, including reductions in river inflow, reduced marine connectivity, constriction of flow between waterbodies, and declines in submerged plant biomass. Management actions are proposed relating specifically to addressing the apparent causes for water quality changes. [ABSTRACT FROM AUTHOR]

Acute (24 h) toxicity tests were conducted to determine the toxicity of the fungicide chlorothalonil towards the freshwater bdelloid rotifer (Philodina acuticornis odiosa). Since rotifers are the dominant zooplankton species in many inland freshwater lakes in Australia, the influence of salinity on chlorothalonil toxicty was also assessed. The rotifers used in this study appeared to be reasonably tolerant to changes in salinity, with little mortality observed at 3760 µS cm-1, increasing thereafter at higher salinity. The bdelloid rotifers were, however, found to be highly sensitive to chlorothalonil (24 h LC50, 3.2 µg L-1) with results also suggesting that as salinity increases, so does toxicity (e.g., 24 h LC50 at 5000 µS cm-1, 0.5 µg L-1). [ABSTRACT FROM AUTHOR]

Cenozoic fluvial sediments present west of the Meckering Line occur at similar elevation ranges (mostly 200-260 m AHD) in the largely rejuvenated forested landscapes of the Darling Plateau between the Helena River catchment and the south coast of Western Australia. These widespread paleovalley sediments are more continuous than previously recognised, and possess common hydrogeological characteristics. The upper parts of catchments in southwest Western Australia are flat and poorly drained with widespread salt lakes and wetland systems developed on the sediments. The lower rejuvenated landscapes below the base of remnant sediments, which are locally marked by saline springs and right angle changes in river courses, have undulating topography with well-defined drainage lines cut into competent basement rocks. This paper identifies groundwater flow systems associated with the paleovalley sediments in three varied catchments and describes the role of the Cenozoic sand aquifer in the development and potential management of dryland salinity. Groundwater flow in the Cenozoic paleovalley sand aquifer has more significance for land and water salinisation than that in the local weathered basement. The sand aquifer is a conduit for salt mobilised from weathered basement following land clearing. Erosion of the sedimentary profile by rejuvenation has exposed this sand aquifer within specific elevation ranges in modern drainages facilitating saline groundwater discharge, and land and water salinisation. In the Helena River catchment 63% of the salt load to the Mundaring Reservoir is discharged through this sand aquifer in only 30% of the streamflow. Such mismatched salt load and flow means southwest landscapes respond differently to key dryland and stream salinity management actions. Revegetation to reduce the salt load should target areas of weathered basement locally discharging saline groundwater to the sand aquifer. Reforestation elsewhere in the rejuvenated bedrock landscape can, by contrast, reduce the streamflow (that is diluting large salt loads from the remnant sedimentary landscapes) and hence raise the overall stream salinity. [ABSTRACT FROM AUTHOR]

Many important water issues such as over-allocation, stream salinity and environmental flows are influenced by the interaction between rivers and underlying aquifers. There are many indirect ways of estimating this flux (such as using hydrographs, tracers or geophysics) but the most common direct method is the use of seepage meters. Over recent decades, various modifications have been made to the basic seepage meter to address potential sources of measurement error and to handle operational issues. These aim to reduce the impact of factors such as upward advection of interstitial water (the Bernoulli effect), venturi effects of stream flow on the collection bag, anomalous short-term influx due to bag properties, gas accumulation in the chamber, frictional resistance causing head losses, ineffective seals and capture of shallow throughflow (rather than groundwater). We have attempted to incorporate these improvements in our seepage meter design and development of simple field procedures, which were trialled in two contrasting catchments (Border Rivers and Lower Richmond) in Australia. The field trials had mixed success, highlighting the potential for spurious seepage flux measurements due to these operational issues. [ABSTRACT FROM AUTHOR]

This paper investigates the link between shrimp farming development and salination processes in the coastal Cai Nuoc district of Ca Mau province, Mekong delta, Vietnam. Surface water, groundwater, and soils were sampled for four consecutive seasons (2002-2004). Salinity in the surface water (40.04-44.78 ‰) was, during the dry season, higher than that of the oceans and remained high during the wet season (more than 8‰). Soils were highly affected by salinity (EC(1/5) 4.57 dS/m), even during the wet season (EC(1/5) 3.78-3.90 dS/m). Salinity levels in both surface water and soils were regulated by seasonal rainfall patterns. The groundwater seemed to be unaffected by shrimp farming development though its salinity level (1.04‰) was higher than the normal values acceptable for human consumption. As a result of shrimp farming development, soil and water salination is currently a serious environmental issue in the Cai Nước district. [ABSTRACT FROM AUTHOR]

The salinity tolerance of two common teleosts from Greece, one a primary division species, Pseudophoxinus stymphalicus, the other a secondary division species, Valencia letourneuxi, was evaluated in laboratory studies. Experimental subjects were acclimated to a salinity of 6 ppt. Through gradual increases, individuals of P. stymphalicus were able to tolerate salinities up to 12-13 ppt, while individuals of V. letourneuxi survived in normal seawater (33 ppt) and had an upper lethal limit of ca. 46 ppt. Valencia letourneuxi, one of two species of the Mediterranean family Valenciidae, is one of the least euryhaline of secondary division teleost fishes. Its distribution matches that of P. stymphalicus, suggesting that its dispersion was not by way of marine waters but by mechanisms used by primary and primary-like freshwater fishes. We reconsider the primary and secondary division and primary-like categories and propose that five basic groups be recognized: primary, primary-like, secondary low salt tolerant, secondary high salt tolerant, and peripheral. [ABSTRACT FROM AUTHOR]

Adult male crayfish, Cherax quadricarinatus, were exposed to the salinities of 0 (control), 7.5, 15, 25 and 35 g L-1 for 3 weeks. Survival, oxygen consumption rate, hemolymphatic levels of glucose, lactate, sodium, potassium, pH, and free amino acids (FAA), as well as FAA concentration in muscle, were determined. Survival was significantly reduced (p < 0.05) only at the highest salinity assayed, together with a significant (p < 0.05) increase of glucose and decrease of lactate. Concerning ions, a hyper-regulation of both hemolymphatic sodium and potassium was maintained up to a salinity of 15 g L-1, at which hemolymph became isoionic with ambient water. A certain degree of ionic hypo-regulation was also noted. Hemolymph pH levels decreased as salinity increased from 0 to 15 g L-1. FAA content in muscle showed an increase parallel to that of hemolymphatic sodium, in accordance with their expected function in the isosmotic regulation of muscular cells. [ABSTRACT FROM AUTHOR]

Lake Urmia is a thalassohaline ecosystem. It is an extremely simple ecological pyramid. This makes it a very sensitive ecosystem. This ecosystem has been facing various threats regarding the amount of water released from the associated basin. To calculate the lake water requirement with an ecological approach, we identified three variables: ecology, water quality, and water quantity indices as environmental indicators. The ecological index represented by Artemia urmiana is considered as an independent variable; while, the water quality index represented by concentration of NaCl, and the water quantity index represented by water elevation are regarded as dependent variables. The salinity threshold of 240 ppt (parts per thousand) is selected as the water quality requirement for Artemia urmiana. Finally, the aggregation of these variables shows that Lake Urmia requires annually 3086 MCM of inflow water to have a sustainable ecosystem. [ABSTRACT FROM AUTHOR]