Salt Stores Research Articles

К истории становления русско-горской торговли на Северном Кавказе в конце XVIII – начале XIX века

The article reveals the features of the formation of trade in the conditions of the North Caucasus, when many unfavorable circumstances complicated this process. In addition to the landscape obstacles that prevented the construction of an extensive network of roads in mountainous areas, the epidemiological threat posed a significant danger. To stop the spread of infectious diseases, quarantine lines were erected, where it was necessary to maintain the isolation periods necessary to detect a possible infection. The funds spent on such measures, as well as the loss of time by merchants, affected the final price of the goods, making them more expensive. For the authorities, trade was a tool of political influence over local peoples. Hence the desire to monopolize contacts between the mountaineers and residents of the settlements bordering them. This approach could influence the range of goods offered, determine the equivalent of their value, limiting the use of money in trade transactions. Gradually, a model of interaction was developed on the established trading platforms (exchange yards, salt stores, fairs). Efforts were made to prevent conflicts, and if they occurred, mechanisms were created to resolve mutual claims. Commodity-money relations replaced natural exchange.

Спектральные характеристики засоленной пашни в предгорной долине Заилийского Алатау (Северный Тянь-Шань) в период 2016–2022 гг. по спутниковым данным Sentinel-2

Introduction. The foothill catchment of the Zailiisky Alatau (Northern Tien Shan), adjacent to the ridge from the north, occupies an altitude range of 475–925 m above sea level and has an area of about 8500 km2. The Almaty urban agglomeration with a population of 2.5 million people is located here and there is a developed agriculture. Crop production in the sharply continental, arid and hot climate of Central Asia is based on irrigation agriculture. For irrigation in the foothill catchment, river runoff from the Zailiysky Alatau Ridge is used. In some parts of the foothill catchment there are salt stores and salt outbreaks in the landscape, which contribute to the salinization of arable land. Secondary salinization of arable land is a negative factor that reduces their quality and productivity. Monitoring the salinity of arable land is practically an important task. The most effective technologies for detailed assessment of soil salinity are based on the processing of satellite data. The purpose of the work. The purpose of this study was to analyze the long-term spectral characteristics of agricultural land potentially susceptible to secondary salinization. This information is necessary to determine optimal strategies in the task of remote assessment of salinization of arable land in the foothill catchment of the Zailiysky Alatau Ridge. Materials and research methodology. The 323 cloudless Sentinel-2 images (10 m resolution) of the period 2016–2022 were selected. Four spectral indices: Normalized Difference Vegetation Index (NDVI); Soil Adjusted Vegetation Index (SAVI); Vegetation Soil Salinity Index (VSSI); and Simple Ratio Index (SRI); were used to monitor the test site, which was located in the northeastern part of the foothill catchment of the Trans-Ili Alatau Ridge. The test site included three polygons of irrigated arable land subjected to secondary salinization, and two polygons of saline abandoned land. The satellite monitoring of spectral indices was used to determine the most informative periods within the season, as well as to assess the inter-seasonal stability of the results. Results and discussion. The dynamics of the considered vegetation indices (NDVI, SAVI and SRI) differed most significantly in July-August, i.e., in conditions of the most developed vegetation. The VSSI index was the most informative in April-May and December-February. The vegetation condition of saline arable lands is controlled by the moisture content and salinity of the rootinhabited soil layer. The precipitation deficit leads to deterioration in the state of vegetation, which masks the negative impact of secondary salinization of fields. Thus, the assessment of the significance of the factor of secondary salinization in the state of vegetation requires annual ground sub-satellite surveys. Conclusion. The variations in the values of the spectral indices of test polygons are very large and depend on the seasonal weather characteristics. Therefore, practically significant satellite methods for assessing the salinity of arable land in the foothill catchment of the Trans-Ili Alatau Ridge should be based on annual sub-satellite surveys. This limits the range of significant remote sensing technologies, methods of extrapolation of sub-satellite surveys data to regular grids, within territories with similar hydrological characteristics and land-use types.

Knowledge, Attitudes, and Practices of Iodized Salt Among Adults Aged 18 to 65 in the United Arab Emirates.

Iodine plays a big role in growth and development and is used in the synthesis of thyroid hormones that regulate body organ functions. Its most important source is iodized salt. Iodine deficiency impairs cognitive development and precipitates many thyroid diseases. The purpose of our study is to measure the knowledge, attitudes, and practices towards iodized salt in adults aged 18-65 years in the United Arab Emirates. This is a cross-sectional study that included 406 participants. A self-administered questionnaire was distributed in public places across the Emirates. The survey included the socio-demographic characteristics of the participants with questions related to knowledge, attitudes, and practices towards iodized salt. A knowledge score out of 13 was calculated. Chi-square, Mann-Whitney U, and Independent T-tests were used for analysis on the Statistical Package for the Social Sciences (IBM SPSS Statistics for Windows, IBM Corp., Version 22.0, Armonk, NY), with a p-value less than 5% considered statistically significant. Out of the 406 respondents, 60% (n=246) were between the ages of 18-34 years and 71% (n=287) were at university level. The mean knowledge score was higher in participants with higher educational levels compared to participants with lower education levels (4.30 vs 2.63, respectively) and in older ages (35-65 years) compared to younger ages (18-34 years) (4.20 vs 3.59, respectively). Almost half of the participants buy iodized salt (48%, n=196), a minority buy non-iodized salt (14%, n=55), and the rest do not know what type of salt they buy. Most of the participants who use iodized salt store it in a closed container and do not expose it to sunlight. Knowledge about iodized salt is relatively low. Less than half of the participants use it, while most of the participants who use iodized salt follow the right storage recommendations. Our study suggests the implementation of public campaigns to raise awareness about the importance of iodized salt and the benefits of using it.

A study on salt produce system in the late choson dynasty

조선 후기에 있어서 소금은 바닷물을 농축하여 끓이는 자염(煮鹽)을 위주로 하여 생산하였다. 자염을 하기 위해서는먼저 염전을 포함한 염장(鹽場)을 설치하여야 한다. 그런데 염장을 설치하자면 우선 근처에 연료가 풍부하여야 유리하였다. 아울러 주변에 넓고 평탄한 갯벌이 있어야 하고, 굴과 같은 조개류가 많으면 더욱 좋았다. 여기에 더하여 수륙 교통이 편리하다면 염장의 생산성은 보다 높아졌던 것이다. 염장에는 몇 가지 시설을 갖추어야 생산이 제대로 이루어질 수 있었다. 그것은 부옥과 함수고, 그리고 염부 및 염창등이다. 아울러 염전 주변으로 수로와 도로가 정비되어 진다면 더욱 유리하였다. 자염을 생산하는 주요한 과정은 먼저염전 갈기이다. 이것은 염전 위에 산포한 토사를 몇 차례 갈아엎어 염분 함량이 높은 함수(鹹水)를 만드는데 필요하였다. 이렇게 생산된 함수를 함수고에 저장하면서 염부에 넣고 달이면, 자염 즉 소금이 만들어졌던 것이다. 부산 명지도 염전의 특징은 다음과 같다. 첫째, 염전까지 수로를 연결하여 현대 염전의 증발지에 바닷물을 공급하듯이 급수가 용이하게 되었다. 둘째, 증발지 형태의 염전으로, 염전 내부에 작은 저수지를 규칙적으로 많이 만들어 해수가 많이 증발하도록 하였다. 이 방법은 조선후기 전통 염전방식과는 판이하게 다르다. 이 방식은 ‘쇄염법(曬鹽法)’의 한방법으로 보다 발전된 형태이다. 셋째, 증발지의 신설로 섯(간수통)이 소멸되었다. 넷째, 함수고가 염전 주위에 많이 설치되었다. 염전의 함수를 1차로 모으고, 이를 인력으로 다시 소금가마 옆의 함수고로 운반하였다.Salt production was very important place in the economy of traditional korea. it is generally produced by boiling sea water, in the late Choson dynasty, that is from the seventeenth to the nineteenth century. This was period of rapid social change and economic development, and the metamorphosis of korean economy and society stimulated salt industry. sea water was kept in salt fields for evaporation, it helped keep the hours of boiling and hence the amount of fuel. other factors included the convenience transportation and salt pot with salt store house and so forth. but the crucial factor in deciding the locality of salt fields was the availability of fuel. this study attempts to delineate the main features of salt industry in the late choson period. the raw material of salt was brine obtained from the sea. the government encouraged the salt production. the shortage of the fuel for salt was filled up by the government. the availability of fuel was the crucial factor in deciding the locality of salt fields. other factors included the convenience of transportation and the adequacy of soil type. Consequently, the salt fields heavily concentrated along the southwestern coast of Korea.

Salinity risk assessment of an irrigation development using treated coal seam gas water in the Condamine River catchment

All irrigation developments inherently carry a salinity risk, due to an unavoidable change in the water and salt balance. The time frame in which either land or water salinity will develop is driven by the ability of the landscape to absorb the change of water and salt supplied. Factors that influence this are landscape attributes, such as the size of the unsaturated zone and its properties (permeability and drainage), management considerations (land-use changes, water application rate and crop water use) and climate variability (temperature and rainfall). This study assessed the risk of secondary salinity expression occurring in an irrigation area in the Condamine-Balonne catchment in southern inland Queensland, Australia. The objectives were to (1) define the depth, size and properties of the unsaturated zone and regolith, (2) define deep drainage rates for past, present and future land uses and (3) assess this information to calculate the risk that groundwater table rise may result in surface salinity expression. Data collected during field investigations was used to conceptualise the regolith architecture, undertake hydrogeological modelling, estimate the available moisture storage capacity of the unsaturated zone and model paddock deep drainage characteristics. The work identified that irrigation-induced deep drainage had started to mobilise salt stores in the unsaturated zone. It also identified connectivity between land management and salt discharges into the Condamine River. As the water supply for the scheme is scheduled to continue until 2030, there is a clear risk of the unsaturated zone moisture storage capacity being exceeded, leading to both land and surface water salt expressions.

A water and salt balance model for the polders and islands in the Ganges delta

Cropping in the polders and islands of the Ganges delta is difficult, particularly in the dry season when water is limited and salinity can damage plant growth. Cropping is generally restricted to the wet season. The limited cropping contributes to the high incidence of poverty and limited livelihood prospects in the region. Increasing crop production is desirable, and will depend upon management of the water and salt in a polder. We have developed a novel time-series model of water and salt stores and flows in an idealised polder to investigate water and salt management strategies for crop production, including strategies to cope with climate change and sea level rise. We know of no other model that simulates the overall water and salt balance of a polder, and that can assess a wide range of polder water and salt management strategies. The model adequately reproduces the dynamic water and salt behaviour observed in field data, and also agrees with results produced by a more detailed crop model. A sensitivity analysis of the model shows the results are sensitive to the key model parameters. In general, the results are more sensitive to parameters governing the transfers of salt, and less sensitive to those governing the availability of water. The crop evapotranspiration is particularly sensitive to the model parameters. The main practical consideration resulting from this simplified but robust representation of the polder salt and water balance processes is the importance of management (including drainage) to remove salt. Strategies to improve water availability, while useful, are secondary to the management of salt.

Hydrogeological Landscapes framework: a biophysical approach to landscape characterisation and salinity hazard assessment

In Australia, salinity has the potential to affect up to 17million hectares of agricultural and pastoral land. For many degraded sites, biophysical hazards are often poorly understood and consequently poorly managed. Attempts to remediate areas affected by salinity have met with varying degrees of success. The New South Wales (NSW) Office of Environment and Heritage, NSW Department of Primary Industries, University of Canberra and Geoscience Australia have collaborated to develop a biophysical expert-based approach for the assessment and management of salinity within landscapes. The Hydrogeological Landscape (HGL) framework provides a structure for understanding how salinity manifests in the landscape, how differences in salinity are expressed across the landscape and how salinity may best be managed. The HGL framework merges the flow dynamics of the groundwater flow system with the landscape elements of the soil landscape or regolith landform approaches. This is the first approach to specifically address all three manifestations of salinity: land salinity, in-stream salt load and in-stream salt concentration. The HGL framework methodology recognises the interplay between surface and subsurface flow systems, as well as the capacity for water to interact with salt stores in the landscape, and identifies biophysical landscape characteristics (e.g. amount and type of vegetation cover, typical land use practice) that affect these interactions. The HGL framework is an expert system that integrates the spatial variability of landscape characteristics and salinity processes to produce a salinity hazard assessment for any given area.

Frontier groundwater investigations in the west Kimberley (Fitzroy) Region: preliminary assessment of groundwater resource potential and the salinity hazard to proposed irrigation developments

A regional reconnaissance AEM survey in the west Kimberley region (lower Fitzroy River valley and May-Meda Catchments) has successfully mapped the extent of regional Canning Basin aquifers (e.g. Pool Sandstone, Grant Group and Erskine Sandstone) confirming these as significant potential groundwater resources. The survey has successfully mapped a multi-layered hydrostratigraphy to depths of ~400m (in resistive areas), also revealing significant tectonics manifested as large scale basin-scale tilting of stratigraphy and more localised folding and faulting. The survey also mapped other key objectives including: the seawater intrusion (SWI) interface for the lower Fitzroy River valley and the May and Meda River Catchments; river flush zones along the Fitzroy, May and Meda Rivers; groundwater salinity variations and potential salt stores in the shallow alluvium of these rivers and proposed irrigation areas. River-parallel surveys also identified reaches of the May and Meda Rivers with direct contact between the rivers and underlying regional aquifers of the Pool Sandstone and Grant Group. These reaches are areas of potential recharge, and/or groundwater discharge, with the AEM used to target hydrochemical investigations, drilling and aquifer testing. The AEM data reveal more complex relationships between perennial in-stream pools along the Fitzroy River, underlying aquifers, tectonics, and river alluvium. AEM survey design incorporated time series analysis of surface water availability through time (Water Observations from Space (WOfS)) derived using the Australian Geoscience Data Cube (AGDC). This has facilitated investigations of surface-groundwater interaction through ensuring the AEM transects coincide with permanent water holes and river reaches considered to be potentially sustained by groundwater discharge. The AEM data provide a framework for hydrogeological process understanding, while the knowledge generated in this project will inform water resource allocation planning, help assess risks to culturally and environmentally sensitive riverine ecosystems, and de-risk investment in agriculture and water infrastructure more broadly.

The East Kimberley Ord Bonaparte Plains Project: de-risking investment in agriculture and water infrastructure through airborne and ground geophysical investigations

The Ord Bonaparte Plains area is a priority area for irrigated agriculture development as part of the Ord Stage 3 development in the East Kimberley region of Western Australia. Irrigated agriculture in this area will depend on access to groundwater resources in underlying bedrock aquifers. A program of airborne electromagnetics (AEM), drilling, ground and borehole geophysics and hydrogeological investigations is being undertaken to confirm the presence of suitable groundwater resources, map the connectivity between surface and groundwater systems, and identify potential risks to agriculture and water infrastructure including salt stores, groundwater salinity and seawater intrusion. Preliminary analysis shows that the AEM survey has successfully mapped key elements of the groundwater system, including aquifer and aquitard extent, groundwater quality (salinity) distribution, hydraulic properties, compartmentalisation and inter-connectivity, the seawater intrusion (SWI) interface in coastal zones, and key tectonic elements of regional hydrogeological significance. The survey has mapped significant faulting within the Cockatoo Sandstone and Point Springs Sandstone aquifers, while conductivity distributions suggest that faults within and bounding major stratigraphic units display both fault barrier and conduit behaviour. The survey has also found that fresh groundwater in the aquifer system continues offshore as discontinuous lenses. Initial inversions have been used to target drilling, hydrochemical investigations, and a program of ground geophysics (including Surface Nuclear Magnetic Resonance (SNMR)). Further analysis and groundwater modelling is required to determine appropriate development and management of any groundwater resource and the potential risks to agricultural development.

Thermal synthesis of a thermochemical heat storage with heat exchanger optimization

Thermochemical materials, particularly salt hydrates, have a significant potential for use in thermal energy storage systems. When a salt hydrate is heated to a critical temperature, a chemical reaction is initiated to dissociate it into its anhydrous form and water vapour. The anhydrous salt stores the sensible energy that was supplied for dehydration, which can be later extracted by allowing cooler water or water vapour to flow through the salt, transforming the stored energy into higher sensible heat. This work presents a thermal synthesis modelling of a thermochemical heat storage based on the reactive porous bed of MgCl2⋅2H2O in a closed system. An analytical sharp front model is also developed to determine the required hydration time and the optimal bed size for such a system at prototype level. A sensitivity analysis helps to identify the optimal parameters that significantly affect the performance of the heat release process. Numerical heat and mass transfer through principal system components is studied using Comsol Multiphysics Software. Numerical results show good concordance with the experiment and reveal that to achieve quasi-complete hydration of the bed, mass flow rate should not be higher than 0.001 kg⋅h−1 for a bed thickness between 4 and 5 cm, considering the present system configuration. In this closed system, inlet vapour pressure into the bed has no influence on the conversion process. Optimal porosity of around 0.76 is found based on the heat and mass transfer dilemma analysis. Optimal heat exchanger design is performed for mass transfer enhancement in the reactive bed.

Salinity hazard and risk mapping of point source salinisation using proximally sensed electromagnetic instruments

In many irrigated areas in the Murray–Darling Basin, New South Wales, Australia, point-source salinisation has occurred in isolated cases. In the lower Macquarie valley, near Trangie and Warren, the cause appears to be the mobilisation of salts from perched water tables and as a function of excessive deep drainage from water storages and conveyance channels. In order to understand these hazard factors and understand the risk of further salinisation, the spatial distribution of the various factors need to be mapped. Two methods have previously been employed and include the use of GIS hazard layer (e.g. geology, topography) analysis or airborne electromagnetic (EM) mapping. The former uses qualitative data which is often unreliable, whilst the latter has large start-up costs. In this study, various sources of proximally sensed data (i.e., EM38, EM34) are first used to develop stepwise-multiple linear regression (MLR) models to map the spatial distribution of vadose-zone (0–7m) clay and salt stores. Using a salt-water balance model (SaLF), deep drainage (mm/year) is estimated. The model has an exponential form and uses ancillary data as predictors. The predicted clay, salt store and deep drainage hazard maps are further employed to develop a map of overall salinity risk using Boolean logic and indicator kriging. Results suggest that the areas exhibiting the largest conditional probability of salinity risk correspond to permeable soil types associated with the Trangie Cowal, Contemporary Macquarie and Backplain of Old Alluvium Pedoderm. It was also noted that the predicted salinity risk was consistent with where salinisation had occurred in both Trangie and Warren districts. The methodology indicated where a more strategic approach needs to be implemented when considering options to improve irrigation efficiencies and water delivery southeast of Warren and Trangie. It also showed where more detailed investigations could be undertaken to better understand the stratigraphic nature of the landscape and the mobilisation of the salts therein.

Origin and dynamics of groundwater salinity in the alluvial plains of western Delhi and adjacent territories of Haryana State, India

AbstractGroundwater salinity is a widespread problem and a challenge to water resources management. It is an increasing concern in the alluvial plains of Delhi and neighbouring Haryana state as well as a risk for agricultural production water supply and sustainable development. This study aims to identify potential sources of dissolved salts and the driving mechanisms of salinity ingress in the shallow aquifer. It combines a comprehensive review of environmental conditions and the analysis of groundwater samples from 25 sampling points. Major ions are analysed to describe the composition and distribution of saline groundwater and dissolution/precipitation dynamics. Density stratification and local upconing of saline waters were identified by multilevel monitoring and temperature logging. Bromide–chloride ratios hold information on the formation of saline waters, and nitrate is used as an indicator for anthropogenic influences. In addition, stable isotope analysis helps to identify evaporation and to better understand recharge processes and mixing dynamics in the study region. The results lead to the conclusion that surface water and groundwater influx into the poorly drained semiarid basin naturally results in the accumulation of salts in soil, sediments and groundwater. Human‐induced changes of environmental conditions, especially the implementation of traditional canal and modern groundwater irrigation, have augmented evapotranspiration and led to waterlogging in large areas. In addition, water‐level fluctuations and perturbation of the natural hydraulic equilibrium favour the mobilisation of salts from salt stores in the unsaturated zone and deeper aquifer sections. The holistic approach of this study demonstrates the importance of various salinity mechanisms and provides new insights into the interference of natural and anthropogenic influences. Copyright © 2011 John Wiley & Sons, Ltd.

Release of stored thermochemical energy from dehydrated salts

Thermochemical materials, particularly salt hydrates, have significant potential for use in thermal energy storage applications. When a salt hydrate is heated to a threshold temperature, a chemical reaction is initiated to dissociate it into its anhydrous form and water vapor. The anhydrous salt stores the sensible energy that was supplied for dehydration, which can be later extracted by allowing cooler water or water vapor to flow through the salt, transforming the stored energy into sensible heat. We model the heat release that occurs during a thermochemical hydration reaction using relations for mass and energy conservation, and for chemical kinetics and stoichiometry. A set of physically significant dimensionless parameters reduces the number of design variables. Through a robust sensitivity analysis, we identify those parameters from this group that more significantly influence the performance of the heat release process, namely a modified Damköhler number, the thermochemical heat capacity, and the heat flux and flowrate. There is a strong nonlinear relationship between these parameters and the process efficiency. The optimization of the efficiency with respect to the parameters provides guidance for designing engineering solutions in terms of material selection and system properties.

Salinisation processes in a sub-catchment of Wybong Creek, Hunter Valley, Australia

Salinisation in the Hunter Valley, New South Wales, Australia, is a significant environmental issue which affects the regional wine, horse and beef industries. The sub-catchment of Wybong Creek causes increased salinity, sodicity and chlorine concentrations in the Hunter River. Sampling was undertaken in the scalded area of Manobalai, located in the mid-catchment area of Wybong Creek, to establish whether salt stores within the regolith, or saline groundwater discharge from deeper formations, are sources of Na+ and Cl− dominated water to Wybong Creek. Ten soil cores were collected from eight sites in the Manobalai area, with bores and piezometers installed to characterise groundwater chemistry and hydraulic head. The regolith within the Manobalai field site was non-saline, though Na+ and Cl− were the dominant ions in most regolith layers. The most saline regolith samples have coarse textures and a high moisture content, and occur in the valley floor. Cores from the salt scald have salt concentrations ranging from 274 to 2089 mg/kg, with a maximum Na+ and Cl− wt.% of 0.17. Saline groundwater in piezometers has total dissolved solid concentrations of up to 7277 mg/L. In this saline groundwater, Cl−/Br− ratios of up to 1767, Na+/Cl− ratios of 0.6–1.2 and 87Sr/86Sr ratios up to 0.709446 indicate halite dissolution and a marine source of solutes to groundwater. The Wittingham Coal Measures, which previous studies have linked to salinity elsewhere in the Hunter Valley, contain halite efflorescences and were intruded by marine water in their geological past. Salinity is due to discharge of this regional groundwater body in the Wybong catchment and not, as commonly assumed within Australia, due to dryland salinity.

Water table response to an experimental alley farming trial: dissecting the spatial and temporal structure of the data

Clearing vegetation for traditional agriculture diminishes native habitat and reduces plant transpiration, leading to increased groundwater recharge and onset of dryland salinization due to rising groundwater and mobilization of salt stores in the soil profile. This change in hydrology and salinity can also negatively affect biodiversity in many semiarid regions. Alternating native perennial tree belts with mono-species agriculture within the tree belt alleys is one possible system that can provide recharge control and recover some of the ecosystem services of degraded agricultural landscapes. To assess the effect of this agroforestry technique on groundwater levels, an alley farming trial was established in 1995, incorporating different combinations of belt width, alley width, and revegetation density. Transects of piezometers within each design have been monitored from October 1995 to January 2008. The data set consisted of 70 piezometers monitored on 39 dates. Two trends were observed within the raw data: An increase in water table depth with time and an increase in the range of depths monitored at the site were clearly discernible. However, simple hydrograph analysis of the data has proved unsuccessful at distinguishing the effect of the tree belts on the water table morphology. The statistical techniques employed in this paper to show the effect of the experiment on the water table were variation partitioning, principal coordinates of neighbor matrices (PCNM), and canonical redundancy analysis (RDA). The environmental variables (alley farming design, distance of piezometer from the tree belt, and percentage vegetation cover including edge effect) explained 20-30% of the variation of the transformed and detrended data for the entire site. The spatial PCNM variables explained a further 20-30% of the variation. Partitioning of the site into a northern and southern block increased the proportion of explained variation for the plots in the northern block. The spatial PCNM variables and vegetation cover remained the most significant variables. The PCNM analysis revealed no spatial pattern that could be attributed to the trial. The high proportion of unexplained variation may be due to site variables that have not been considered in this study.

Salt mapping in the Lower Macquarie area, Australia, using airborne electromagnetic data

An airborne electromagnetic survey was flown over 13 000 km2 in the Lower Macquarie Valley in central New South Wales, Australia. Whilst bulk conductivity values from the survey provide useful insights into the regional hydrogeology of the area, mapping salinity and salinity hazards requires the derivation of salt store values from the survey data. This paper describes the methodology of deriving salt stores from conductivity data and accompanying physical measurements. A post-flight sampling programme involving physical, chemical, electromagnetic and geological examination of cores from eight drill holes provides field-based measurements through which the bulk conductivity data can be related to salt stores. Linear models were generated to understand the relationship between salt stores, conductivity and other parameters, and to produce an optimum salt store map from the data. A strong relationship was evident between observed salt stores and drill hole-derived observations, which include parameters such as conductivity, lithology, stratigraphy, lithostratigraphy/weathering and depth. The main predictor for salt stores was observed conductivity with only a minor influence due to lithology. Significant salt stores are predicted at depth in the northern part of the survey. Superficial salt stores are generally low (<4 kg/m3) in the Lower Macquarie and should not pose a threat to native vegetation or agricultural activities.

Water and salt balance of a saline water disposal basin during an experimental flooding and drying cycle (Loveday Disposal Basin, Australia)

AbstractSaline irrigation drainage water along the semi‐arid lower River Murray is often disposed of into evaporation basins to prevent contamination of downstream water supplies. These evaporation basins are often former ephemeral floodplain wetlands that have now become extremely ecologically degraded due to high soil and water salinity. An experimental flooding with freshwater was conducted at Loveday Disposal Basin in 2006 to evaluate the environmental benefits of periodic flooding with freshwater. The water and salt balances of the permanent North Basin and ephemeral South Basin during the experiment were evaluated using a combination of hydrometric techniques and trends for salinity and the stable isotopes of water. Filling of the basins (with freshwater from the River Murray) decreased salinity (as total dissolved solids) from approximately 60 to 9 g l−1. Once flooding was completed, water level in both basins receded rapidly and then within 5 months they had re‐salinised to pre‐treatment levels. The main re‐salinisation mechanism was greater evaporative loss induced by the large increase in wetted surface area after flooding, especially in the shallower South Basin. Dissolution of evaporites was not a source of salt to the basins because halite remained undersaturated at all times, but minor quantities of Ca2+ and SO42− were gained from gypsum and carbonate dissolution. The salt mass stored in South Basin surface water increased during flooding and early after flooding, suggesting a significant salt input from the flooded soils. Because of large salt stores in surrounding soils and groundwater, ongoing saline groundwater discharge, and large evaporative losses, periodic flooding alone brings limited environmental benefits (that is, conditions favourable to freshwater organisms) to floodplain disposal basins. However, flooding deeper disposal basins during winter will minimise evaporative losses and increase the length of the freshening period. Copyright © 2009 John Wiley &amp; Sons, Ltd.

Evaluation of salt sources and loads in the upland areas of the Murray–Darling Basin, Australia

AbstractEstimates of catchment salt balances throughout the Murray‐Darling Basin (MDB) suggest mobilization of salt stores and generally increasing stream salinities. It is widely assumed these salts are rainfall‐deposited cyclic salts of marine‐aerosol origin, concentrated by evapotranspiration, stored in groundwaters and mobilized by clearing of native vegetation. In this paper, the assumptions about the sources of salts, in upland catchments in the south‐eastern region of the MDB are re‐evaluated. The estimation of dissolved salts is re‐examined using electrical conductivity (EC), the assessment of stream salt loads from sporadic EC measurements and the sources of salts in upland catchments. It is concluded that, although evapotranspiration plays a significant role in the concentrations of salts in the lower MDB, mineral weathering is a major contributor to stream salt loads in upland rivers of the MDB that supply over 80% of surface runoff to the Murray River. Copyright © 2009 John Wiley &amp; Sons, Ltd.

Utilizing airborne electromagnetic data to map groundwater salinity and salt store at Chowilla, SA

The Chowilla floodplain in South Australia is part of the Bookmark Biosphere Reserve with wetlands supporting a wide range of plants and animals, and has provided recreational opportunities to the general public (MDBC, 2006). However, the threats from saline groundwater and salt accumulation at the surface, combined with the overall low rainfall and the lack of natural flooding events in the recent past, have had a negative consequence for vegetation health, especially the river red gums. Information on the spatial patterns of groundwater salinity and the near surface (top 15 m) salt stores in the floodplain is integral to our understanding of floodplain hydrological processes that may be active in the Lower Murray Basin of Australia. This information can be used to help develop appropriate remedial activities for the management of ecologically important wetlands and in particular assist in the maintenance of a healthy vegetation community. A helicopter-borne electromagnetic (HEM) survey was conducted across the floodplain in conjunction with a validation drilling and borehole geophysical logging program. Based on the laboratory results from cored sediments and their pore fluids, we report on the salinity and salt store models calculated from the inverted HEM data.

Utilizing airborne electromagnetic (EM) data, high resolution DEM and hydrogeological information to derive customised products for natural resource management along the River Murray corridor

To improve on earlier hydrogeological models and to better manage the River Murray floodplain environment and water resources from salinity and irrigation impacts, stakeholders in the New South Wales and Victorian Mallee worked with project scientists to identify hydrogeological parameters that might be collected from existing data sets to help resolve land and water management issues (Lawrie at al., 2008). Several areas where improved information were identified, including the extent and thickness of the river flush zone, salt stores in both the unsaturated and saturated zones, and the thickness, extent and depth to the top of the Blanchetown Clay and other clay units across the floodplain and its adjacent uplands. Previous AEM-based studies have demonstrated the potential for these data to provide high geospatial resolution of key elements of the hydrogeological system (Walker et al., 2004). An airborne electromagnetic (AEM) survey was flown in early 2007 along a 450 km stretch of the Murray River and its floodplains in Victoria from the South Australian-Victorian border to Gunbower. The data were acquired under the auspices of the Australian Government?s Community Stream Sampling and Salinity Mapping Project, and were managed by the Bureau of Rural Sciences. This survey utilised a Fugro RESOLVE frequency domain system, with flight lines at 200m line spacing, and oriented at a high angle to the river corridor. RESOLVE is a six frequency EM system mounted in a bird towed beneath a helicopter at a nominal altitude of 30 m. The bird contains horizontal coplanar coils and measure EM responses at 390 Hz, 1798 Hz, 8177 Hz, 39470 Hz and 132700 Hz. It also has one coaxial coil pair which measured a response at 3242 Hz. This paper presents methods for mapping the thickness of Blanchetown Clay in the highlands of the areas surveyed during the course of this work, and the distribution of near surface clay across the floodplains, specifically at Lindsay-Wallpolla, Lake Victoria, Darling River and its anabranch.