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The interaction between climate warming and alien fish invasions could have severe consequences in inland waters, which represent isolated environments with high biodiversity richness. Due to the current climatic trend, increasing water temperatures and salinization, shorter ice cover period, and altered flow regimes are predicted for these environments. The aim of this review is to offer a comprehensive analysis at a global scale of the recent studies available in the literature, focused on the responses of invasive freshwater fish to the effects of climate change in both lotic and lentic environments. To achieve this purpose, we selected 34 relevant papers, using the Scopus and Google Scholar database. New alien species establishment, distribution range expansion of species already introduced, and exacerbating impacts on freshwater ecosystems and the native fish communities they host were included in the topics covered by the analyzed papers. Despite the uncertainties related to the unpredictability with which the effects of global warming will occur, the findings of the selected studies served as a support to evaluate conservation and management implications, with particular reference to possible mitigation strategies. [ABSTRACT FROM AUTHOR]

Managed Aquifer Recharge (MAR) is a promising method of increasing water availability in water stressed areas by subsurface infiltration and storage, to overcome periods of drought, and to stabilize or even reverse salinization of coastal aquifers. Moreover, MAR could be a key technique in making alternative water resources available, such as reuse of communal effluents for agriculture, industry and even indirect potable reuse. As exemplified by the papers in this Special Issue, consideration of water quality plays a major role in developing the full potential for MAR application, ranging from the improvement of water quality to operational issues (e.g., well clogging) or sustainability concerns (e.g., infiltration of treated waste water). With the application of MAR expanding into a wider range of conditions, from deserts to urban and coastal areas, and purposes, from large scale strategic storage of desalinated water and the reuse of waste water, the importance of these considerations are on the rise. Addressing these appropriately will contribute to a greater understanding, operational reliability and acceptance of MAR applications, and lead to a range of engineered MAR systems that help increase their effectiveness to help secure the availability of water at the desired quality for the future. [ABSTRACT FROM AUTHOR]

Drinking water in much of Asia, particularly in coastal and rural settings, is provided by a variety of sources, which are widely distributed and frequently managed at an individual or local community level. Coastal and near-inland drinking water sources in South and South East (SSE) Asia are vulnerable to contamination by seawater, most dramatically from tropical cyclone induced storm surges. This paper assesses spatial vulnerabilities to salinisation of drinking water sources due to meteorological variability and climate change along the (ca. 6000 km) coastline of SSE Asia. The risks of increasing climatic stresses are first considered, and then maps of relative vulnerability along the entire coastline are developed, using data from global scale land surface models, along with an overall vulnerability index. The results show that surface and near-surface drinking water in the coastal areas of the mega-deltas in Vietnam and Bangladesh-India are most vulnerable, putting more than 25 million people at risk of drinking 'saline' water. Climate change is likely to exacerbate this problem, with adverse consequences for health, such as prevalence of hypertension and cardiovascular diseases. There is a need for identifying locations that are most at risk of salinisation in order for policy makers and local officials to implement strategies for reducing these health impacts. To counter the risks associated with these vulnerabilities, possible adaptation measures are also outlined. We conclude that detailed and fine scale vulnerability assessments may become crucial for planning targeted adaptation programmes along these coasts. [ABSTRACT FROM AUTHOR]

Bangladesh is recognized as one of the most vulnerable countries due to climate-induced sea level rise and further exacerbation of the current conditions is anticipated in light of the projected climate scenarios. Saltwater intrusion to fresh water resources is one of the most important impacts of sea level rise in low-lying costal areas. Despite the widespread and growing problem of water salinity and population affected in low-lying coastal areas including in Bangladesh, evidence on human health impacts of water salinity is scarce. One important health risk potentially related to water salinity is high blood pressure. The epidemiological research examining the health impacts of drinking water sodium (water salinity) on blood pressure and as a consequence to other health conditions such as heart diseases, stroke, and kidney damage is yet to be explored. Given the extent of the problems of water salinity globally and in Bangladesh, further research is urgently required to assess the risk of water salinity on blood pressure and other health conditions within different populations and age groups, in order to promote appropriate prevention strategies. This paper describes the impacts of sea level rise and saltwater intrusion and identifies potential research gaps in order to make relevant policy recommendations in the context of coastal Bangladesh and similar settings in low-income countries. [ABSTRACT FROM AUTHOR]

Salinization threatens the viability of water resources and is common in many important inland freshwater lakes worldwide, especially in arid and semi-arid areas. Bosten Lake is a typical inland freshwater lake that has evolved into a subsaline lake and is located in the arid region of Northwest China. The water resources of Bosten Lake are important for supplying regional drinking water and agricultural irrigation and for economic development. In this study, changes in salinity with time and space were analyzed in Bosten Lake. Overall, the salinity increased from 0.39 g/L in 1958 to 1.87 g/L in 1987, reaching its highest value in 1987. After 1987, the salinity decreased to 1.17 g/L in 2003 and increased to 1.45 g/L in 2010. Increased salinity adversely affects aquatic lake systems, regional eco-environments and water resource use, and has become a serious environmental problem in Bosten Lake. Thus, the causes of increasing salinity are discussed in this paper. Overall, the influences of climate variations and human activities resulted in the salinization of the lake. Understanding the salinization processes in Bosten Lake can be useful for implementing actions that improve water quality and water resource use in the lake. [ABSTRACT FROM AUTHOR]

This article describes LIMPACS, a research initiative designed by the International Geosphere-Biosphere Program. The LIMPACS programme is designed to assess how and why lakes have changed, are changing and might change in the future as a result of human activity. The article outlines the program's major set of foci, such as: climate forcing, climate variability, land/ocean dynamics, and human-environment interactions. Other papers in this volume are based on a meeting of scientists to develop research priorities.

Abstract Worldwide, delta areas are under stress due to climate change. With rising sea levels and decreasing freshwater availability, surface water salinization due to groundwater exfiltration is expected to increase in these low-lying areas. To counteract surface water salinization, freshwater diverted from rivers is used to flush agricultural ditches. In this paper, we demonstrate a Model Predictive Control (MPC) scheme to control salinity and water levels in a water course while minimizing freshwater usage. A state space description of the discretized De Saint Venant and advection-dispersion equations for water and salt transport, respectively, is used as the internal model of the controller. The developed MPC scheme is tested using groundwater exfiltration data from two different representative Dutch polders. The tests demonstrate that water levels and salinity concentrations can successfully be controlled within set limits while minimizing the freshwater used. Highlights • A real time control method is proposed for optimal flushing of polder systems. • Low-order physical model is employed to formulate model predictive control problem. • Water level and salinity regulation is achieved by minimizing the freshwater use. • A quadratic program is formulated and solved to optimize regulation. • 35–45% savings in freshwater used is realized compared to traditional flushing. [ABSTRACT FROM AUTHOR]

The paper deals with coastal aquifers exploitation under saline intrusion threats and climate change effects over them. For sustainable development of these resources variable but necessary policies are required, among them: selection of abstraction works and their appropriate design, knowledge of the aquifer system, control measures over variables for decision making, use of advanced technologies to define optimal exploitation strategies, efficient operation and maintenance of existing works. It is suggested, when feasible, to give preferential use to horizontal works but avoiding open trenches because of the inconveniences that have been observed in the Cayo Largo del Sur and Andros-Bahamas case studies. The use of vertical wells demands a careful design, not only of each well but also of their spatial distribution, therefore the paper includes some recomendations to this end. [ABSTRACT FROM AUTHOR]

The natural Australian landscape sustains a mosaic of wetlands that range from permanently wet to temporary. This diversity of wetland types and habitats provides for diverse biotic communities, many of which are specific to individual wetlands. This paper explores the prospects for southern Australian wetlands under modified water regime and salinity induced by climatic changes. Extended droughts predicted as a consequence of climate change (lower rainfall and higher temperatures) combined with human-induced changes to the natural hydrological regime will lead to reductions in the amount of water available for environmental and anthropogenic uses. Reduced runoff and river flows may cause the loss of some temporary wetland types that will no longer hold water long enough to support hydric communities. Species distributions will shift and species extinctions may result particularly across fragmented or vulnerable landscapes. Accumulation of salts in wetlands shift species-rich freshwater communities to species-poor salt tolerant communities. Wetlands will differ in ecological response to these changes as the salinity and drying history of each wetland will determine its resilience: in the short term some freshwater communities may recover but they are unlikely to survive and reproduce under long term increased salinity and altered hydrology. In the long term such salinized wetlands with altered hydrology will need to be colonized by salt tolerant species adapted for the new hydrological conditions if they are to persist as functional wetlands. As the landscape becomes more developed, to accommodate the need for water in a warmer drying climate, increasing human intervention will result in a net loss of wetlands and wetland diversity. [ABSTRACT FROM AUTHOR]

This paper reports on the qualitative and quantitative screening of groundwater sources for integration into the public water supply system of the Algarve, Portugal. The results are employed in a decision support system currently under development for an integrated water resources management scheme in the region. Such a scheme is crucial for several reasons, including the extreme seasonal and annual variations in rainfall, the effect of climate change on more frequent and long-lasting droughts, the continuously increasing water demand and the high risk of a single-source water supply policy. The latter was revealed during the severe drought of 2004 and 2005, when surface reservoirs were depleted and the regional water demand could not be met, despite the drilling of emergency wells. For screening and selection, quantitative criteria are based on aquifer properties and well yields, whereas qualitative criteria are defined by water quality indices. These reflect the well's degree of violation of drinking water standards for different sets of variables, including toxicity parameters, nitrate and chloride, iron and manganese and microbiological parameters. Results indicate the current availability of at least 11001 s-1 of high quality groundwater (55% of the regional demand), requiring only disinfection (9001 s-1) or basic treatment, prior to human consumption. These ground-water withdrawals are sustainable when compared to mean annual recharge, considering that at least 40% is preserved for ecological demands. A more accurate and comprehensive analysis of sustainability is performed with the help of steady-state and transient groundwater flow simulations, which account for aquifer geometry, boundary conditions, recharge and discharge rates, pumping activity and seasonality. They permit an advanced analysis of present and future scenarios and show that increasing water demands and decreasing rainfall will make the water supply system extremely vulnerable, with a high risk of groundwater salinization and ecosystem degradation. [ABSTRACT FROM AUTHOR]

Fisheries constitute an important source of livelihoods for tens of thousands of poor people in the southwest coastal region of Bangladesh, and they supply a significant portion of protein for millions. Among the various threats fisheries in the southwest coastal region will face because of climate change, adverse impacts from increased aquatic salinity caused by sea level rise will be one of the greatest challenges. This paper investigates possible impacts of climate change on aquatic salinity, fish species habitats, and poor communities using the salinity tolerance ranges of 83 fish species consumed in the region and aquatic salinity in 27 alternative scenarios of climate change in 2050. The results provide striking evidence that projected aquatic salinization may have an especially negative impact on poor households in the region. The estimates indicate that areas with poor populations that lose species are about six times more prevalent than areas gaining species. [ABSTRACT FROM AUTHOR]

A rapid warming and freshening of the Southern Ocean have been observed over the past several decades and are attributed to anthropogenic climate change. In this study, ocean model perturbation experiments are conducted to separate roles of individual surface forcing in the Southern Ocean temperature and salinity changes. Model-based findings are compared with results from a theoretical framework including three idealized processes defined on the θ–S diagram. Under the future scenario of CO2 doubling, the heat flux forcing dominates the large-scale warming, deepening of isopycnals, and spiciness changes along isopycnals, which can be captured by an idealized pure warming process to represent the subduction of surface heat uptake. The poleward-intensifying westerly winds account for 24% of the enhanced warming between 35° and 50°S and would have comparable contribution as the heat flux forcing after removing the global ocean warming effect. In contrast, the widespread freshening in the Southern Ocean driven by increased surface freshwater input is largely compensated by the wind-driven saltening. The response to freshwater forcing could not be approximated as a similar pure freshening process as the induced cooling and freshening have comparable effects on density. The wind-driven changes are primarily through the local heave of isopycnals, thus resembling an idealized pure heave process, but contain considerable spiciness signals especially in the midlatitude Southern Ocean, resulting from anomalous northward transport and subduction of heat and salt that are largely density-compensating. These distinct signatures of individual surface forcing help us to better understand observed and projected changes in the Southern Ocean. Significance Statement: Considerable changes including a rapid warming and freshening have been observed in the Southern Ocean as it absorbs most of the extra heat from the anthropogenic climate change, receives increased surface freshwater input, and experiences a poleward shift and intensification of the westerly winds. The purpose of this study is to distinguish different contributions from surface heat flux, freshwater flux, and wind forcing to the Southern Ocean temperature and salinity changes, based on ocean model experiments and three idealized processes from a theoretical framework. Our study reveals distinct signatures of individual surface forcing that help us to understand linkages between changes seen at the surface and in the interior Southern Ocean. [ABSTRACT FROM AUTHOR]

More than 30% of Germany's final energy consumption currently results from thermal energy for heating and cooling in the building sector. One possibility to achieve significant greenhouse gas emission savings in space heating and cooling is the application of aquifer thermal energy storage (ATES) systems. Hence, this study maps the spatial technical potential of shallow low-temperature ATES systems in Germany. Important criteria for efficient ATES operation considered in this assessment encompass suitable hydrogeological conditions, such as aquifer productivity and groundwater flow velocity, and balanced space heating and cooling demands. The latter is approximated by the ratio of heating and cooling degree days, which is incorporated as a time-dependent criterion to also evaluate the impact of climate change on the ATES potential. The hydrogeological and climatic criteria are combined within a spatial analysis revealing that, regarding the upcoming decades, about 54% of the investigated German area are very well or well suitable for ATES applications, largely concentrating on three regions: the North German Basin, the Upper Rhine Graben and the South German Molasse Basin. Considering time-dependent climatic conditions, the very well or well suitable areas will increase by 13% for the time period 2071–2100. This is mostly caused by a large relative area increase of the very well suitable regions due to an increasing cooling demand in the future. The sensitivity of the very well and well suitable regions to the criteria weightings is relatively low. Accounting for existing water protection zones shows a reduction of the country-wide share of very well or well suitable areas by around 11%. Nevertheless, the newly created potential map reveals a huge potential for shallow low-temperature ATES systems in Germany. [ABSTRACT FROM AUTHOR]

Under the ongoing and potential risks from anthropogenic warming, net negative carbon dioxide (CO2) emissions are inevitable to stabilize or recover the Earth's climate. It is important not only to understand climate irreversibility in response to CO2 removal but also to understand how fast each component of the climate system will recover to its original state. Based on idealized CO2 ramp‐up and ‐down ensemble simulations, here we show that the initial buoyancy states of the Arctic Ocean, such as upper ocean salinity and density, are vital to determining how fast Arctic and global mean temperatures will recover on a centennial time scale. The denser initial Arctic oceanic condition is linked to faster recovery of the Atlantic meridional overturning circulation (AMOC) in the ramp‐down period, which is further accelerated by strong positive AMOC‐salt‐advection feedback. Faster AMOC recovery can delay Arctic temperature recovery by transporting warmer water into the northern subpolar Atlantic during the ramp‐down period. In addition, denser Arctic water enhances vertical mixing, which also results in delayed Arctic cooling under a strong vertical temperature gradient in the subpolar‐to‐polar Atlantic. Our findings suggest that the Arctic's initial states have a centennial memory for the future Arctic and global climate changes. Plain Language Summary: Understanding whether anthropogenic global warming is irreversible, and how fast our climate system will recover to its original state is of great socio‐economic benefit as this is closely related to future climate adaptation and policy decisions. In this study, we investigate what determines the recovery speed of the Arctic temperature. We found that the most uncertain region in response to carbon dioxide (CO2) removal is the Arctic. The Arctic temperature shows a strong inter‐ensemble spread when the CO2 concentration returned to the present level. This different Arctic temperature in each ensemble member can be explained by the density and salinity of the Arctic Ocean about a century ago. For example, a denser Arctic Ocean condition in the early CO2 reduction pathway slows down the recovery of the Atlantic meridional overturning circulation (AMOC) in the presence of positive AMOC‐salt‐advection feedback. Because faster AMOC recovery can transport more warm water into the Atlantic sector of the Arctic, Arctic cooling as a result of CO2 reduction is delayed. Our findings suggest that the Arctic's initial states have a centennial memory for the future Arctic and global climate changes. Key Points: The carbon dioxide removal ensemble simulation shows that the Arctic climate changes exhibit the largest ensemble spread, suggesting the most uncertain regionThe initial buoyancy condition of the Arctic Ocean has a centennial memory for the future recovery of Arctic temperatureThe denser Arctic Ocean is linked to faster recovery of the Atlantic meridional overturning circulation (AMOC) and Arctic temperature, with strong AMOC‐salt‐advection feedback [ABSTRACT FROM AUTHOR]

In this paper, we present the results of a comprehensive survey concerning environmental awareness and vulnerability, conducted in October 2013 in the Yellow River Delta, China. The purpose of this survey is to provide insight to the vulnerability of rural households and their livelihoods to internal and external threats, such as flooding, oil spills, droughts, erosion, and salinization. Education level, awareness, opinions regarding pollution and available public utilities and facilities are also polled. Specific questions regarding agriculture and aquaculture activities are included. It is the most comprehensive questionnaire regarding social vulnerability in the area to date, with 93 households interviewed with the aid of an interpreter. The results show that the respondents generally have a low education; many earn below minimum wage for the area, and are not aware of global processes of climate variability and sea level rise. Cotton and maize are the predominant agriculture crops farmed in the area, while ground salinization is a major threat to agriculture. The results of this survey can be used in a follow up study in conjunction with a separate spatial data analysis (e.g. earth observation, census) to assess the social vulnerability in the Yellow River Delta in a spatially representative fashion. [ABSTRACT FROM AUTHOR]

One of the major causes of crop stress is soil or water salinity. Thus, selection of the best species for cultivation in semiarid and arid climates is fundamental. Salvadora persica is an evergreen perennial halophyte that can grow under extreme conditions, from very dry environments to highly saline soils. Based on international bibliography, the authors outlined an agro-ecological zoning model to determine the potential cultivation zones for S. persica in Argentina. This model may be applied to any part of the world, using the agro-ecological limits presented in this work. All the maps were developed by the implementation of a geographic information system (GIS) that can be updated by the further incorporation of complementary information, with the consequent improvement of the original database. The overlap of the agroclimatic suitability map on the drylands' saline soils and the drylands' alkaline soils maps, determined the agro-ecological zoning. Since some areas in the agro-ecological zoning can overlap with land that is already assigned for other uses, protected areas, current land use/cover of the different zones, and urban areas maps were incorporated into the GIS and subtracted by a mask. This resulted in the delimitation of “potential cultivation zoning”, thus avoiding possible conflicts surrounding the use of land and making the agro-ecological zonation more efficient. There is a broad agro-ecological zone for cultivation of S. persica that extends from Northern Argentina to approximately 41° South latitude, under dry-subhumid to semiarid climates. Lands classified with different degrees of suitability in the potential cultivation zoning could be used for production of this species for energy purposes on lands that are either unsuitable for food production or currently assigned for other purposes. This paper represents pioneering work since there are no previous studies concerning the introduction of S. persica in Argentina. [ABSTRACT FROM AUTHOR]

As a major hotspot of climate change, Lebanon suffers from a water resources crisis enhanced by the increase of anthropogenic activities. In this paper, the impacts of climate change and of the Syrian refugee crisis are combined with the impact of demographic growth to assess their aggregated impact on seawater intrusion in the Tripoli aquifer. A hydrogeological model is used to assess the seawater intrusion evolution for the next 25 years with respect to three phenomena: seawater rise, variation of incoming freshwater flux, and the change of the extraction rate of the pumping wells. Our study shows that the freshwater/seawater interface will move forward inland about 103 m in the next 25 years, leading to the salinization of the aquifer at the position of the pumping wells. Only about 1% of the advancement of the interface is associated with seawater rise; the remaining contributions are 79% from climate change and 20% from demographic growth. Adding the impact of migration reduces the contribution of climate change from 79% to 52%. The results suggest that the remediation solutions and recommendations should take into account the long-term impacts of climate change and the impact of population migration. [ABSTRACT FROM AUTHOR]

Mesozooplankton play a crucial role as primary or secondary consumers in Arctic ecosystems and are sensitive indicators of environmental changes. This research is the first comprehensive Arctic zooplankton study covering the area ranging from the southern Chukchi Sea (SCS) and the northern Chukchi Sea (NCS) to the East Siberian Sea (ESS). Mesozooplankton samples were collected at 151 stations in the western Arctic Ocean each August from 2016 to 2020. The mesozooplankton abundance of the study area ranged from 9 to 6,172 ind. m−3, and the predominant group was copepods at 7–3,866 ind. m−3, of which Pseudocalanus spp. and Calanus glacialis were the most abundant copepods. In the SCS, small copepods and meroplankton, such as Pseudocalanus spp., Cirripedia larvae, Echinodermata larvae, and Centropages abdominalis were the predominant taxa. Especially in 2019, C. abdominalis dominated over meroplankton when water temperatures were high (maximum 12.5°C; sea surface temperature, SST). In the NCS and ESS, C. glacialis, Pseudocalanus spp., Metridia longa, Oithona similis, Parasagitta elegans, and Calanus hyperboreus were abundant. The distributions and structures of mesozooplankton communities indicated variability over large spatial scales in the western Arctic waters because of variations in multiple factors, such as water temperature, salinity, and sea ice; however, geographical effects cannot be ignored even during alterations in the physical properties. Our results suggest that these variable patterns of mesozooplankton communities fluctuate horizontally from south to north as warming progresses on a regional bathymetric basis, and can be used to infer the fate of mesozooplankton communities in the study area. Plain Language Summary: Zooplankton play a crucial role as consumers in Arctic ecosystems and are sensitive indicators of environmental changes. This research is the first comprehensive Arctic zooplankton study from the southern Chukchi Sea to East Siberian Sea. Here, we evaluated zooplankton community studies in the western Arctic Ocean from 2016 to 2020. The most dominant zooplankton group was copepods, among which Pseudocalanus spp. and Calanus glacialis were the most abundant copepods. In the SCS, small copepods and meroplankton, such as Pseudocalanus spp., Cirripedia larvae, Echinodermata larvae, and Centropages abdominalis were the predominant taxa. Especially in 2019, C. abdominalis dominated over meroplankton when water temperatures were high (maximum 12.5°C, sea surface temperature). In the northern Chukchi Sea and East Siberian Sea, C. glacialis, Pseudocalanus spp., Metridia longa, Oithona similis, Parasagitta elegans, and Calanus hyperboreus were abundant. The distributions and structures of mesozooplankton communities indicated variability over large spatial scales in the western Arctic waters because of variations in multiple factors, such as water temperature, salinity, and sea ice; however, geographical effects cannot be ignored even during alterations in the physical properties. Future zooplankton communities in this area are expected to fluctuate horizontally from south to north due to changes in various factors depending on regional depth variation. Key Points: This is the first comprehensive Arctic zooplankton study from the Chukchi Sea to the East Siberian SeaWater temperature, salinity, and depth have been shown to possess a significant effect on the community structure of the mesozooplanktonPatterns of interannual mesozooplankton communities have been fluctuated horizontally from south to north on a regional bathymetric basis [ABSTRACT FROM AUTHOR]

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Despite the fact that the Baltic Sea is a semi-enclosed sea of the North Atlantic Ocean, it is characterized by variability of different hydrophysical and hydrochemical parameters according to the recent studies. Over one hundred years of observations of water temperature and salinity variations have shown that thermohaline regime (circulation, system) has begun to change: trends of increasing water temperature and decreasing water salinity were determined. Scientists from the Baltic countries seek to attract societies' attention to the possible structures of the Baltic Sea hydrology and changes in water balance associated with climate change. This paper searches for the impact of low-frequency atmospheric fluctuations in Atlantic and Pacific surface temperature on water temperature and salinity changes in the Baltic Proper in 1960-2009. The previous studies have shown that there are weak links between the Baltic Sea water temperature, salinity and NAO (North Atlantic oscillation) and AO (Arctic oscillation) that affect the Baltic region. Recently, it was also found that the Baltic Sea hydrophysical and chemical parameters depend on large distance relationships between climate anomalies teleconnection. The determined relationships between the multi-annual average temperature and salinity of the Baltic Sea water column and seasonal, annual indices of the Atlantic Ocean (AMO, AMM, Atlantic Tripole) are weak, whereas links between the Baltic Sea investigated parameters and Pacific index: ONI (Oceanic Nino Index) are very weak (r = -0.32). The strongest correlation exists between water temperature and the NAO (0.36 = r = 0.45), AMM (0.37 = r = 0.40) and between water salinity and NAO (-0.38 = r = -0.51), PNA (Pacific- North American index) (0.27 = r = 0.34). [ABSTRACT FROM AUTHOR]

Abstract: Climate change impacts on the hydrological cycle, e.g. leading to changes of precipitation patterns, have been observed over several decades. Higher water temperatures and changes in extremes hydrometeorological events (including floods and droughts) are likely to exacerbate different types of pressures on water resources with possible negative impacts on ecosystems and human health. In addition, sea-level rise is expected to extend areas of salinisation of groundwater and estuaries, resulting in a decrease of freshwater availability for humans and ecosystems in coastal areas. Furthermore, climate-related changes in water quantity and quality are expected to affect food availability, water access and utilisation, especially in arid and semi-arid areas, as well as the operation of water infrastructure (e.g. hydropower, flood defences, and irrigation systems). This paper serves as an introduction to the special issue of Environment Science & Policy dealing with climate change impacts on water-related disasters. It provides a brief background about relevant EU water policies and examples of EU-funded research trends which illustrate on-going efforts to improve understanding and modelling of climate changes related to the hydrological cycles at scales that are relevant to decision making (possibly linked to policy). [Copyright &y& Elsevier]

Abstract: In this paper we present a modelling study to investigate the impacts of climate change on the chloride concentration and salinisation processes in two man-made freshwater lakes in the Netherlands, Lake IJsselmeer and Lake Markermeer. We used a transient compartmental chloride and water balance model to elucidate the salinisation processes occurring under present conditions and assess future salinisation under two climate forcing scenarios. The model results showed that the Rhine River is the dominant determinant for the chloride concentration in both lakes, followed by drainage of brackish groundwater from the surrounding polders. The results further show that especially during dry years, seawater intrusion through the tidal closure dam is an important source of chloride to Lake IJsselmeer. The results from the climatic forcing scenarios show that Lake IJsselmeer is especially vulnerable to climate-induced salinisation whereas effects on Lake Markermeer are relatively small. Peak chloride concentrations at the raw water intake of the Andijk drinking water facility on Lake IJsselmeer are projected to increase to values above 250 mg/l in the most far-reaching climate change scenario W+ in 2050 for dry years. This is well above the maximum allowable concentration of 150 mg/l for chloride in drinking water. Modelling showed that climate change impacts the chloride concentrations in a variety of ways: 1) an increasing occurrence of low river flows from summer to autumn reduces the dilution of the chloride that is emitted to the Rhine with a constant load thereby increasing its concentration; 2) increased open water evaporation and reduced rainfall during summer periods and droughts increases the chloride concentration in the water; and 3) rises in sea level increase seawater intrusion through the tidal closure dam of Lake IJsselmeer. The processes described here are likely to affect many other tidal rivers or lakes and should be considered when planning future raw water intake stations for drinking water production or agricultural water supply. [Copyright &y& Elsevier]

Contamination of water through salinization will affect the well-being of livestock. Therefore, it is necessary to understand how animals respond to increasing levels of salts in their water supply. This short communication describes the effects of a two-week salinity stress (0, 6, 12 g L− 1 NaCl) on Pelibuey sheep. The parameters measured in response to salinity stress were animal weight, rectal temperature, and levels of hemoglobin, hematocrits, lymphocytes, neutrophils, leukocytes and proteins. Specific activities of superoxide dismutase (SOD) and catalase (CAT) in blood samples were also recorded. The results showed that the 6 g L− 1 NaCl treatment resulted in the significantly highest body weight. There were no significant differences in the rectal temperature of animals. In terms of the hematological parameters, animals exposed to 6 g L− 1 NaCl displayed the significantly highest hemoglobin and hematocrit contents. There appeared to be no effect of consumption of saline water on the amount of lymphocytes, neutrophils, leukocytes or proteins. It was found that animals that consumed 12 g L− 1 NaCl supplemented water had the lowest levels of SOD activity. There were no significant differences in CAT specific activities in animals exposed to the saline water or the control. This is the first report on the response of Pelibuey sheep to short-term saline stress under Cuban environmental conditions. [ABSTRACT FROM AUTHOR]

The Washington State Department of Ecology conducted a large-scale ocean acidification (OA) study in greater Puget Sound to: (1) produce a marine carbon dioxide (CO2) system dataset capable of distinguishing between long-term anthropogenic changes and natural variability, (2) characterize how rivers and freshwater drive OA conditions in the region, and (3) understand the relative influence of cumulative anthropogenic forcing on regional OA conditions. Marine CO2 system data were collected monthly at 20 stations between October 2018 and February 2020. While additional data are still needed, the climate-level data collected thus far have uncovered novel insights into spatiotemporal distributions of and variability in the regional marine CO2 system, especially at low salinities in shallow, river-forced shelf regions. The data provide a strong foundation with which to continue monitoring OA conditions across the region. More importantly, this work represents the first successful long-term OA monitoring program undertaken at the state-level by a regulatory agency. Therefore, we offer the work described herein as a blueprint to help state and local scientists and environmental and natural resource managers develop, implement, and conduct long-term OA monitoring programs and studies in their own contexts and jurisdictions. [ABSTRACT FROM AUTHOR]

The low-lying coastal basins of Ravenna (Italy) are at or below mean sea level and currently undergoing land subsidence, which exposes the basins to frequent inundation and groundwater and soil salinization. The surface water drainage becomes necessary to lower the water table head and further prevent flooding and waterlogging. The study examines the evolution of drainage apropos to climate change and land subsidence in the three main Ravenna coastal basins. Our findings show that the evolution of drainage is influenced by land subsidence, climate change variability, droughts, vertical seepage, and local water management. Land subsidence causes an increase in upward-directed vertical seepage of saline water through the shallow unconfined aquifer into the drainage channels of the coastal basins, thus leading to an increase in drainage through time. At a seasonal timescale, the rate of pumping depends on antecedent rainfall and soil–water storage. The warming extremes indices, specifically drought indices, show to be more significant than rainfall indices trends to monitor drainage evolution. Drought indices permit easy comparison of dryness or wetness severity with drainage evolution along their time scale. The co-occurring anthropogenic and natural factors involving in the increasing drainage rate will affect decadal and seasonal water management policies in the area. The implications of increasing drainage rates, long periods of drought with limited rainfall, and increasing temperature will further worsen freshwater availability in this coastal area already experiencing soil and water salinization. However, drainage of this low-lying territory has effectively mitigated rising water tables and avoided flooding. Our study has shown that each coastal basin behaves differently in terms of sensitivity to land subsidence and climate extremes. Therefore, when using drainage data time series for water management purposes, one should account for past management practices and for the specific sensitivity of each basin to external factors. [ABSTRACT FROM AUTHOR]

We reconstruct deep water‐mass salinities and spatial distributions in the western North Atlantic during the Last Glacial Maximum (LGM, 19–26 ka), a period when atmospheric CO2 was significantly lower than it is today. A reversal in the LGM Atlantic meridional bottom water salinity gradient has been hypothesized for several LGM water‐mass reconstructions. Such a reversal has the potential to influence climate, ocean circulation, and atmospheric CO2 by increasing the thermal energy and carbon storage capacity of the deep ocean. To test this hypothesis, we reconstructed LGM bottom water salinity based on sedimentary porewater chloride profiles in a north‐south transect of piston cores collected from the deep western North Atlantic. LGM bottom water salinity in the deep western North Atlantic determined by the density‐based method is 3.41–3.99 ± 0.15% higher than modern values at these sites. This increase is consistent with: (a) the 3.6% global average salinity change expected from eustatic sea level rise, (b) a northward expansion of southern sourced deep water, (c) shoaling of northern sourced deep water, and (d) a reversal of the Atlantic's north‐south deep water salinity gradient during the LGM. Plain Language Summary: Twenty thousand years ago, the atmosphere had a much lower temperature and contained less insulating carbon dioxide (CO2) gas than it did even before the human induced CO2 rise of the last centuries. Confirming if the carbon "missing" from the atmosphere 20,000 years ago was stored away in the deep ocean will help us predict where the carbon humans add to the atmosphere will end up over the next few millennia. We find the temperature and amount of salt (salinity) in today's waters by measuring them directly, but to find them in the past ocean we measure chemical compounds that are buried over time in the seafloor. In this study, we measure the density of water collected from the north Atlantic seafloor to estimate the past salinity. Our results support previous findings that 20,000 years ago the deep Atlantic was filled with more carbon‐rich water that sank from the surface in the Southern Ocean than in today's Atlantic, accounting for up to two‐thirds of the carbon "missing" from the atmosphere 20,000 years ago. Key Points: Paleosalinities of Last Glacial Maximum (19–26 ka) North Atlantic Bottom waters are 3.41–3.99 ± 0.15% higher than modern valuesNew paleosalinities support expansion of salty, southern sourced water displacing fresher, northern sourced water in the Last Glacial Maximum (LGM) deep AtlanticPaleosalinities are more precise when from porewater densities measured on ship from cores that span the LGM porewater chloride maximum [ABSTRACT FROM AUTHOR]

Biological invasions are a major cause of biodiversity loss and, coupled with climate change, will likely have detrimental impacts for native species and the functioning of ecosystems. To mitigate such impacts, it is important to elucidate the behavioural mechanisms underpinning interactions between invasive and native species. Here we examined how competitive interactions between invasive and native species are modified under conditions of near-future elevated water temperature using freshwater crayfish as a model system. Contest experiments between the native Euastacus spinifer and invasive Cherax destructor revealed that the competitive advantage of E. spinifer at current maximum temperatures (22 °C) was reversed at elevated near-future temperatures (26 °C), after controlling for relative body size. In addition, the native crayfish spent twice as long motionless at 26 °C than C. destructor, consistent with physiological challenges underpinning this competitive reversal. Most alarmingly, E. spinifer experienced significant mortality after fighting C. destructor, particularly at 26 °C. Mortality usually ensued two days post-contest even when E. spinifer had won. Mortality was rare when fighting conspecifics. Together, these results suggest that while E. spinifer is more likely to win contests under current conditions, it could suffer considerable impacts if climate change and the spread of invasive C. destructor continue unabated. [ABSTRACT FROM AUTHOR]

Climate change presents a critical threat to human security on multiple levels. Over one billion people live in low-lying areas and coastal cities where populations and vital infrastructure are at catastrophic risk of rising sea levels. Sixty percent of the chronically hungry already live in at-risk areas and salinization of fresh water and loss of agricultural land are expected to dramatically decrease food security. The loss of territory and conflict over scarce resources is expected to incite regional wars as well, adding to the large unregulated movements of displaced populations. In addition, rising seas and monsoons are expected to contribute to increases in infectious diseases, especially among vulnerable populations. This study examines the existential threat of rising sea levels caused by climate change and offers a predictive model to anticipate the impact of climate change across the three geopolitical regions of Europe, Asia, and sub-Saharan Africa. [ABSTRACT FROM AUTHOR]

Salinization of freshwater ecosystems represents a potential threat to biodiversity, but the distribution of salinity tolerance among freshwater organisms and its functional consequences are understudied. In this study, we reviewed global patterns of salinity tolerance across a broad range of freshwater organisms. Specifically, we compared published data on LC (a metric of salinity tolerance) across climatic regions, taxa, and functional feeding groups (FFGs). We found that microinvertebrates were more sensitive to salinity than vertebrates and macroinvertebrates. Within aquatic insects, there was considerable variability in tolerance across FFGs. Specifically, scrapers, gatherers, and filterers were more sensitive on average than omnivores, shredders, and predators. Thus, we predict that increasing salinization can negatively impact trophic diversity and in turn cause overall changes in the structure and function of freshwater ecosystems. We also identified both historical exposure and taxonomic affinity as potential drivers of contemporary salinity tolerance across freshwater organisms. Finally, we found important gaps in our understanding of the potential impacts of salinization on freshwater biodiversity, particularly in regions expected to be affected by increased salinization due to climate change and secondary salinization. Understanding the differential vulnerability of freshwater taxa is critical to predicting the ecosystem impacts of salinization, and informing conservation and management decisions. [ABSTRACT FROM AUTHOR]

Persistent pressures from water-related threats – sea-level rise, soil and water salinization, and flooding due to embankment overtopping and failure – have made the West Bengal Sundarbans a challenging place to live, and effects of global climate change will only worsen conditions. Four alternative policy directions are examined: business as usual; intensive rural development; short-term out-migration of residents; and embankment realignment and facilitation of voluntary, permanent out-migration. The last of these is the recommended approach. Study findings have informed ongoing deliberations to build consensus on future policy directions for reducing the region’s vulnerability to natural disasters. [ABSTRACT FROM PUBLISHER]

The wide range of ecological goods and services provided by tropical coastal lagoons and wetlands are under considerable pressure due to the synergistic effects of local anthropogenic impact and global climate change. In transitional waters, salinity is a key driver of ecological processes mostly depending on the balance between marine and river inputs, a balance that can be significantly modified by climate change and by anthropogenic alteration of the watershed. Mesoamerica being considered as a climate change hot-spot and as an ecoregion strongly vulnerable to global change, our study aimed at analyzing the relationship between salinity, river runoff, and rainfall variability in a tropical coastal lagoon and to assess the respective influence of climate change and watershed management. The study focusing on the large and shallow coastal lagoon of Laguna de Terminos in south eastern Mexico established: (1) the variability in salinity distribution along the yearly cycle and the occurrence of a high salinity anomaly period during the wet season of 2009; (2) the relationship between lagoon waters salinity and river inputs further underlying the anomalous situation encountered in 2009; (3) a long term increase in river discharge during the past 60 years, indicating potential salinity decrease in the lagoon during that same period; (4) an absence of any change in rainfall linking the increase in runoff to watershed management rather than long term trend in climate change. Additionally, the specific context of the 2009-2010 Central-Equatorial Pacific El Niño is underlined and the potential relationship between river discharge and ENSO is discussed. Those results should be of significant practical value to decision-makers who are often keen to point the finger at global climate change when local environmental management is also and sometime most significantly responsible. [ABSTRACT FROM AUTHOR]

Fresh groundwater reserves on small coral islands are under continual threat of salinization and contamination because of droughts, storm-surge overwash events, over-extraction, island community urbanization, and sea level rise. Whereas storm-surge overwash events can cause sudden groundwater salinization, long-term changes in rainfall patterns and sea level elevation have the potential of rendering these islands uninhabitable in the coming decades. This study demonstrates the use of a tested freshwater lens thickness simulator to estimate the groundwater resources of a set of atoll islands in the coming decades. The method uses ranges of projected rates of annual rainfall and sea level rise (SLR) to provide a range of probable lens thickness for each island. Projected rainfall is provided by General Circulation Models that accurately replicate the historical rainfall patterns in the geographic region of the islands. Methodology is applied to 68 atoll islands in the Federated States of Micronesia. These islands have widths that range between 150 and 1000 m, and experience annual rainfall rates of between 2.8 and 4.8 m. Results indicate that under average conditions of SLR, beach slope, and rainfall, almost half of the island will experience a 20% decrease in lens thickness by the year 2050. For worst-case scenarios (high SLR, low rainfall), average decrease in lens thickness is 55%, with almost half of the islands experiencing a decrease of greater than 75% and half of the islands having a lens thickness less than 1.0 m. Small islands (widths less than 400 m) are particularly vulnerable because of shoreline recession. Groundwater on islands in the western region is less vulnerable to SLR because of a projected increase in rainfall during the coming decades. Results indicate the vulnerability of small islands to changing climatic conditions, and can be used for water resources management and community planning. Methodology can be applied to any group of islands as a first approximation of the effect of future climate conditions on groundwater resources. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Lake Purrumbete is a deep volcanic freshwater lake, cylindrical in shape, located within an extensive basalt plain in southeastern Australia. A modified difference water budget method for lakes, that estimates net groundwater flux through the difference between the level of the lake and the water table, along with the specific yield and area of the aquifer, successfully modelled the lake level fluctuations. The major influences are evaporation and direct precipitation; however groundwater fluxes are significant (~17%). The salt balance modelling shows that the salinity in Lake Purrumbete is largely controlled by groundwater and surface water fluxes. Lake Purrumbete has a greater interaction with the surrounding groundwater system than other nearby volcanic lakes due to its significant depth and the presence of highly permeable basalts along the upgradient shoreline. Its low salinity reflects the substantial salt export in the groundwater and surface outflow, as well as the lake’s relatively small evaporation due to the low surface area/volume ratio. The fluctuations in lake level and salinity for Lake Purrumbete are much less than for other lakes in the region, even during the 1997–2010 drought, due partly to the large, relatively constant groundwater flux. Low salinity, deep water and estimated depth of stratification from this study, which leads to a distinct limnology, implies that the creatures need to adapt to a different habitat to survive in the vicinity of Lake Purrumbete. Thus, Lake Purrumbete will be an important aquatic ecosystem refugium if climate change causes frequent seasonal drying of other lakes in the plain, and it is important to develop management strategies to maintain its water resources and quality.Editor D. Koutsoyiannis Associate editor Not assigned [ABSTRACT FROM AUTHOR]

Salinization of coastal groundwater systems causes a severe deterioration both in amount and quality of fresh groundwater resources. To support the sustainable use and management of fresh groundwater, quantification and characterization of these coastal resources are important in view of the population growth anticipated in many African countries. Analytical methods were used to determine: (1) the shape and volume of the freshwater lens, (2) the elevation of the water table, (3) the depth of the freshwater/saltwater interface in the Shela aquifer, and (4) the expected change of volume resulting from change of recharge and sea level rise driven by climate change. The results of the analytical modelling have shown that the average hydraulic conductivity is 0.755 m/d, the average water table elevation is 2 m above sea level and the average depth of the freshwater/saltwater interface is -80 m.a.s.l. The volume of the aquifer is ≈124 × 10 m when discharge from the Shela well field is factored in. Climate change is expected to have an impact on the recharge and ultimately the aquifer's volume; under the A1b conditions, the volume is expected to increase to 199 × 10 m whereas in the A2 scenario it is expected to decrease to 27 × 10 m. The saltwater intrusion indicator M for today's conditions (0.004) decreases to 0.5 M in the A1b scenario by 2100 whilst it increases to 24.9 M in the A2 scenario for the same time period, indicating an extremely higher vulnerability to saltwater intrusion in the latter scenario. A simple linear correlation with the expected population growth of 1.25 million people by 2050 shows the aquifer failing as a water source by 2033. [ABSTRACT FROM AUTHOR]

Climate changes have increased soil and water salinity, compromising animal production especially in dry areas where scientists have become more interested in halophyte plants, like saltbush. The effects of saltbush hay levels (30, 40, 50 and 60%) were evaluated based on physical-chemical, nutritional and sensory parameters of Santa Inês lamb meat. Thirty-two 8-month-old castrated Santa Inês lambs, with initial weights of 22±1.97 kg were used; they were slaughtered after 60 days in the feedlot. The pH, colour, moisture, protein and cholesterol contents did not differ among treatments. Panelists observed a greater intensity of lamb smell and flavour (P=0.0035) in the meat of animals that received more concentrate in the diet. An increase in the inclusion of saltbush increased ash percentage (P=0.0232), total saturated (P=0.0035) and polyunsaturated (P=0.0287) fatty acids and reduced the lipids (P=0.0055) and the n-6:n-3 ratio (P=0.0058) of the meat. Therefore, saltbush hay can be used as a feeding resource in regions with problems of water and soil salinity because it does not impair the physicalchemical, nutritional and sensory quality of sheep meat. [ABSTRACT FROM AUTHOR]

Abstract: The Antarctic Intermediate Water (AAIW) exhibits a decadal variability during recent years, i.e., salinification before 1997 and freshening thereafter, with the maximum anomalies locating at the region of Brazil and Malvinas currents confluence. Our study proposed that the local mesoscale eddies may play an important role in triggering this decadal oscillation. The eddy activity intensification (weakening) leads to the increase (decrease) of poleward cross-frontal eddy salinity flux and upward eddy buoyancy flux, which results in the weakening (strengthening) of the subsurface stratification and potential vorticity (PV). The PV anomalies facilitate (block) the poleward transport of warm saline subtropical water, while the stratification weakening favors the further downward transmission of salinity anomalies by processes of eddy flux as well as mean-flow advection (the stratification strengthening inhibits the vertical transport), then initiates the decadal change of the AAIW property. The whole process of the eddy-related propagation of salinity anomalies takes about 4 to 6 years. [Copyright &y& Elsevier]

Identifying the relative importance of stressors is critical for effectively managing and conserving freshwater aquatic ecosystems. However, variability in natural ecosystems and the potential for multiple stressors make understanding the effects of stressors challenging in the field. To address these challenges, we assessed four common stressors in the northeastern USA including acidification (pH), climate change (water temperature), salinization (Na and Cl), and nutrient addition using laboratory mesocosms. Each stressor was evaluated independently, with ten mesocosms assigned across a gradient of concentrations for each stressor (total N = 40). We then monitored the effects of the stressors on a model community consisting of periphyton, zooplankton, Northern watermilfoil ( Myriophyllum sibericum), American ribbed fluke snail ( Pseudosuccinea columella), and larval American bullfrogs ( Lithobates catesbeianus). Aquatic stressors varied in the strength of their effects on community structure: Nutrient addition was the least influential stressor, with no significant effects. Acidification influenced periphyton biomass, but not higher trophic levels. Water temperature influenced primary productivity and survival of amphibian larvae, but not intermediate trophic levels. Finally, road salt led to decreases in productivity for all trophic levels included in our model systems. Our results support the findings of prior research, although the effects of acidification and nutrient addition were less pronounced in our study. Importantly, we found that road salt had the most far-reaching effects on a model aquatic community. Given that road salt is the most easily managed of the stressors we compared, our results indicate that improving the condition of freshwater aquatic ecosystems in the northeastern USA may be a feasible objective. [ABSTRACT FROM AUTHOR]

General Circulation Models (GCMs) are applied to Gansu Province, northwest China, to assess temporal and spatial trends of precipitation and temperature, and the trends compared to historical trends. The simulations for the three regions of the Province indicate that temperatures will increase by 3, 3.4 and 3.2 °C for the East, Mid and West regions, while precipitation will be reduced by 50, 50 and 1 mm, respectively in the future. For SRES scenarios of higher population growth, the changes will be larger, followed by the scenarios of fast economic and technologic growth. Based on climate simulations, adaptations of cropping patterns will be needed in the West region since large amounts of irrigation for current cropping patterns will increase the risk of salinization and desertification unless adopted in the planning. Although the current situation for the West region of the Province is most severe, the risk of conditions being drier is shown to be higher for the Mid region. The Mid region has been highly dependent on natural precipitation; highly variable irrigation water quantities will be needed in the future since precipitation in this region varies significantly from year to year. [ABSTRACT FROM AUTHOR]

Regional climate models project significant changes in temperature and rainfall over the Greater Mekong Subregion over the twenty-first century. The potential impacts of climate change on areas affected by waterlogging and shallow saline groundwater in Northeast Thailand was investigated using the variable density groundwater model SEAWAT supported with recharge estimates derived from the hydrologic model HELP3. The focal area is the 154 km Huai Kamrian subwatershed. Changes in groundwater salinity and waterlogging areas at the middle and end of this century were predicted using the calibrated model. These predictions used the dynamically downscaled PRECIS regional climate change scenarios generated by ECHAM4 GCM A2 and B2 scenarios. Recharge rates are predicted to increase as a result of the higher intensity of rainfall. Shallow watertable areas are projected to increase by approximately 23 % from existing conditions during the middle of the century and up to 25 % by the end of this century. Although the precise rate and timing of climate change impacts are uncertain, all of the scenarios clearly point towards an extension in the area of waterlogging and area affected by shallow saline groundwater areas. Given that areas affected by shallow saline watertables are predicted to expand for both climate change scenarios as well as for the base case, it is concluded that climate change will have a significant impact on the area affected by salinity and waterlogging areas for both climate change scenarios. Evaluation of management options that explore the adaptation to saline environments and to means to reduce salt affected areas are required. [ABSTRACT FROM AUTHOR]

Increases in Arctic temperatures have accelerated melting of the Greenland icesheet, exposing intertidal organisms, such as the blue mussel Mytilus edulis, to high air temperatures and low salinities in summer. However, the interaction of these combined stressors is poorly described at the transcriptional level. Comparing expression profiles of M. edulis from experimentally warmed (30 °C and 33 °C) animals kept at control (23‰) and low salinities (15‰) revealed a significant lack of enrichment for Gene Ontology terms (GO), indicating that similar processes were active under all conditions. However, there was a progressive increase in the abundance of upregulated genes as each stressor was applied, with synergistic increases at 33 °C and 15‰, suggesting combined stressors push the animal towards their tolerance thresholds. Further analyses comparing the effects of salinity alone (23‰, 15‰ and 5‰) showed high expression of stress and osmoregulatory marker genes at the lowest salinity, implying that the cell is carrying out intracellular osmoregulation to maintain the cytosol as hyperosmotic. Identification of aquaporins and vacuolar-type ATPase transcripts suggested the cell may use fluid-filled cavities to excrete excess intracellular water, as previously identified in embryonic freshwater mussels. These results indicate that M. edulis has considerable resilience to heat stress and highly efficient mechanisms to acclimatise to lowered salinity in a changing world. [ABSTRACT FROM AUTHOR]

Coastal lakes are often under the threat of sea water ingress causing the depletion of fresh water bodies. Salinization due to sea water ingress causes impact on water resources especially in coastal areas. Thus there is scarcity of fresh water in this region. Climate change causes rise in sea level and this leads to increase of salinity in coastal lakes. Satellite imagery analysis now plays a prominent role in the quick assessment of water quality in a vast area. This study is an attempt to assess the extent of a lake system affected by sea water (Akkulam-Veli lake, Kerala, India) using Indian Remote Sensing Satellite, IRS P6 LISS III imagery. Field data were collected on the date of the satellite overpass. Simple regression equation using radiance in red band is found to yield superior results for the prediction of sodium content whereas polynomial equation using radiance of red band is found to yield superior results for the prediction of chloride content than the simple and multiple regression equations using spectral ratios and radiance from the individual bands from satellite imagery. The refractive index of water containing sodium chloride is more when compared with that of fresh water and this in turn results in high reflection of visible light in the red band when compared to blue and green bands. Hence the radiance of red band gives direct measure of sodium and chloride in lake water. IRS P6-LISS III imagery can be effectively used for the assessment of sea water affected area of the lake system. [ABSTRACT FROM AUTHOR]

It is generally difficult to quantify exactly the freshwater going in or out of the coastal watersheds along the northern Adriatic Sea because, on one hand, excess water is drained and pumped into the sea to prevent flooding but, on the other hand, water is brought onto the land from far away for irrigation. Fragmentation of water authorities makes it difficult to collect all the necessary information. Climate change and increasing salinization of the coastal aquifers make it imperative, however, to better know the quantities of freshwater involved in these small basins. The water budget of a small coastal agricultural watershed along the Adriatic Sea in Italy (The Quinto Basin near Ravenna) is presented here considering different land uses. The evaporation of open water and the evapotranspiration of wetlands, pine forests, bare soil and irrigated agriculture are calculated based on the Penman-Monteith equation and the Cropwat program. The current water budget is based on average climate data from 1989 to 2008 and drainage and irrigation data. Predictions for future evapotranspiration, net irrigation and hydrologic deficit are calculated with climate data from IPCC (The Fourth Assessment Report (AR4) 200, Climate change . From the study results, the soil type may determine whether or not a crop will need more or less irrigation in the future. Regulations on land use should therefore consider which crop type can be grown on a specific soil type. Water budget analysis in scenarios A1b and A2 both show an increase of water deficits in the summer and an increase of water surplus in the winter. This is explained by the fact that a larger percentage of the rain will fall in winter and not during the growth season. The open water evaporation will decrease under future climate scenarios as a result of increased relative humidity in winter and decreased wind velocity. This may have a positive effect on the water cycle. The current irrigation is very abundant, but has beneficial effects in contrasting soil salinization and saltwater intrusion into the coastal aquifer. [ABSTRACT FROM AUTHOR]

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Road maintenance in winter using de-icing agents, which is widely used in Eastern Europe, is the cause of water salinization in neighbouring environments, which might lead to biodiversity loss in aquatic ecosystems. In this study, we investigated NaCl toxicity to test young organisms: Daphnia magna and Poecilla reticulata (standard tests organisms). The salinity of NaCl was measured by electrolytic conductivity (EC). It was statistically demonstrated that the test solutions should be prepared using natural water. For D. magna the NOEC was 7.17 mS/cm and the LC50 9.76 mS/cm. Poecilla reticulata showed resistance to salinity up to a conductivity of 25.2 mS/cm, and no lethal effects were recorded for any individual in the test population. The study showed that winter salinities recorded in inland waters (without emergencies such as sudden influx of pollutants due to industrial accidents) are unlikely to affect fish but may be hazardous to small plankton. However, the high dare of D. magna may result in a reduction of planktivorous fish. [ABSTRACT FROM AUTHOR]

Observations of soil moisture and salt content were conducted from May to August al Neleger station in eastern Siberia. Seasonal changes of salt and soil moisture distribution in the active layer of larch forest (undisturbed) and a thermokarst depression known as an alas (disturbed) were studied. Electric conductivity ECo of the intact forest revealed higher concentrations that increased with depth from the soil surface into the active layer and the underlying permafrost: 1 mS cm-1 at 1-1 m. to 2·6 mS cm-1 at 160 cm depth in the permafrost. However, a maximum value of 5-4 mS cm-1 at 0.6 m depth was found in the dry area of the alas. The concentration of ions, especially Na+, Mg2+, Ca2+, SO42- and HCO3- in the upper layers of this long-term disturbed site, indicates the upward movement of ions together with water. A higher concentration of solutes was found in profiles with deeper seasonal thawing. The accumulation of salts in the alas occurs from spring through into the growing season. The low concentration of salt in the surface soil layers appears to be linked to leaching of sails by rainfall. There are substantial differences between water content and electric conductivity of soil in the forest and alas. Modern salinization of the active layer in the alas is epigenetic, and it happens in summer as a result of spring water collection and high summer evaporation; the gradual salt accumulation in the alas in comparison with the forest is controlled by the annual balance of water and salts in the active layer. Present climatic trends point to continuous permafrost degradation in eastern Siberia increasing the risk of surface salinization, which has already contributed to changing the landscape by hindering the growth of forest. [ABSTRACT FROM AUTHOR]

Global climate change can have a significant impact on the development and sustainability of agricultural production. Climate scenarios indicate that an expected increase in air temperature in semiarid Uzbekistan can lead to an increase in evapotranspiration from agricultural fields, an increase in irrigation water requirements, and a deterioration in the ameliorative status of irrigated lands. The long-term mismanagement of irrigation practices and poor conditions of drainage infrastructure have led to an increase in the water table and its salinization level in the northwestern part of Uzbekistan. This article presents the results of an analysis of the amelioration of irrigated lands in the Khorezm region of Uzbekistan as well as the modeling of the dynamics of water table depths and salinity levels using the Mann–Kendall trend test and linear regression model. The study estimated the water table depths and salinity dynamics under the impact of climate change during 2020–2050 and 2050–2100. The results show that the water table depths in the region would generally decrease (from 1.72 m in 2050 to 1.77 m by 2100 based on the Mann–Kendall trend test; from 1.75 m in 2050 to 1.79 m by 2100 according to the linear regression model), but its salinity level would increase (from 1.72 g·L−1 in 2050 to 1.85 g·L−1 by 2100 based on the Mann–Kendall trend test; from 1.97 g·L−1 in 2050 to 2.1 g·L−1 by 2100 according to the linear regression model). The results of the study provide insights into the groundwater response to climate change and assist authorities in better planning management strategies for the region. [ABSTRACT FROM AUTHOR]

In arid and semi-arid areas, the groundwater is the main source of water supply and agricultural activity. Overexploitation of coastal aquifers and pollution vulnerability are among the main problems related to groundwater resources assessment and management in these zones. In fact, in the last decades, these resources have been threatened by a degradation of their quality and quantity that furthers natural and anthropic effects, such as climate change, seawater intrusion and overexploitation. However, the protection and management of these resources requires knowledge of the origin of their mineralization. In this study, the Essaouira basin is selected as a typical example. Stable isotopes (18O and 2H) together with geochemical data were used to identify the groundwater salinization origin in the coastal aquifers of the Essaouira basin. The results of both the approaches show that the groundwater mineralization is due to: (1) the dissolution of salt minerals, (2) the ion exchange phenomena, (3) seawater intrusion (1-7%), and (4) sulphate reduction. Also, the recharge is supported by fast infiltration of oceanic precipitation without significant evaporation. [ABSTRACT FROM AUTHOR]