Origin and modelling of water salinization in a coastal aquifer of the Bay of Bengal: The Kaluvelly watershed, Tamil Nadu, India

2006 ◽  
Vol 177 (6) ◽  
pp. 333-345 ◽  
Author(s):  
Noémi D’ozouville ◽  
Sophie Violette ◽  
Nathalie Gassama ◽  
Aline Dia ◽  
Nathalie Jendrzejewski

Abstract Over-pumping of the Vanur sandstone aquifer has led to a lowering of the piezometric surface and degradation of water quality through increased salinization. This aquifer salinization is a good example of many similar problems in India and other parts of the world. The Vanur Formation is the main aquifer of a multilayered system bordered by the sea on the eastern side and partly overlaid by the brackish waters of the Kaluvelly swamp in the north. The origin of the salinity, which apparently is not simply seawater intrusion, and its dynamics are examined, using chemical and isotopic tools together with 1D hydrological modelling of the movement of the seawater/fresh water interface. The content of major elements and some trace elements as well as isotopic ratios (18O/16O, D/H and 87Sr/86Sr) were measured in groundwater, surface and rainwater during five sampling surveys (January 1999 to October 2001). Available data on rainfall, piezometric and hydrogeologic records were used. We identified human contamination by F, Li in parts of the aquifer, which invalidated their use as tracers. The chemical composition of water from the Vanur aquifer shows a classical chemical evolution from the recharge area to the deeper confined area, consisting in increased water-rock interaction and a subsequent increase of solute species. However, the range of major compound concentration ratios for some wells does not follow this general trend. The non-consistent points are located in the most depressed area of the aquifer (−20 m amsl in June 2000), except in the north where the brackish water of the Kaluvelly swamps seems to enter the aquifer. In the depressed area, the sulphate signature corresponds to a mixing with a mineralized and sulphate-rich water body, likely to be Ramanathapuram sandstone water. It is due to the upward leakage from this underlying formation. A seasonal evaporation signature recorded by stable isotopes (δ18O, δD) suggests the addition of return irrigation flow. The 1D hydrodynamical model of the sea-water/fresh water movement was built with the available geological and hydraulic data. Hydrodynamic calculations show that seawater intrusion can be expected to occur within 3 to 20 years after the year 2000, depending on the value of unknown parameters (porosity) or boundary conditions (recharge, pumped volume). But we cannot rule out that a lithologic or tectonic barrier prevent any seawater intrusion inland; future geological investigation has to be done to confirm or infirm this hypothesis.

Author(s):  
J. R. Lumby

Comparison of the conceptions which have hitherto been held in regard to the hydrography of the English Channel with those which are offered as a result of the recent activities of the Atlantic Slope Committee, shows that a difference exists which, in the writer's opinion, lies in the interpretation of the material, rather than in the fundamental differences in the material itself. For example, it is stated that the physical character of the water in the English Channel is conditioned, especially in the summer months, by that of the North Sea water rather than by that of the Atlantic water. “En plein été, en août, les eaux chaudes de la mer du Nord affluent dans la Manche.” A similar regimen is suggested for the waters of the Irish Sea, which are said to be derived from the northward. Carruthers shows that the normal water movement in the eastern part of the English Channel is through Dover Straits into the Southern Bight, this movement appearing to be more persistent along the bottom than on the surface. Furthermore, one of the two months in which reversal of this direction appears least likely to occur is August.


2016 ◽  
Vol 18 (3) ◽  
pp. 599-610 ◽  

<div> <p>Seawater intrusion has been a serious problem in the Indus River Estuary (IRE) for decades. The literature reviews, hydrological and meteorological observations were analyzed to examine and discuss the causes and consequences of seawater intrusion in the IRE. Both sea water intrusion and coastal erosion are having a devastating environmental and social impact and the whole ecosystem of the Indus Delta is facing serious threat. The Indus deltaic region is not only threatened by continuing activities upstream but also by the neighboring sea in the south, due to the impacts of local weather conditions. Observational results suggest that seawater intrusion reaches 84 km upstream in the IRE during the dry season. Extensive field investigations and a high resolution coastal ocean model are urgently needed for future study.</p> </div> <p>&nbsp;</p>


1757 ◽  
Vol 50 ◽  
pp. 635-639
Keyword(s):  

Thy kind acceptance of my last emboldens me to inform thee, how, on my return from a voyage to the north part of Russia, I procured a sufficient quantity of fresh water from sea-water, without taking with me either instruments or ingredients expressly for the purpose.


2018 ◽  
Vol 38 (01) ◽  
Author(s):  
V. Sabareshwari ◽  
A. Ramya

Coastal region covers a long strip along the east coast (West Bengal, Orissa, Andhra Pradesh, Pondicherry and Tamil Nadu) and west coast (Gujarat, Maharashtra, Karnataka and Kerala). Salinity is mainly due to the presence of saline ground water at shallow depth and frequent sea water inundation in the low lying areas. Sea water intrusion into the aquifers may be direct, but also range of complex geochemical processes like, inter-aquifer mixing, mobilization of brines, water-rock interaction and anthropogenic contamination. NaCl and Na2SO4 are the dominant salts, with abundance of soluble cations in the order of Na>Mg>Ca>K. The salt reaches the soil surface through capillary rise during dry season and makes the soil saline and unproductive for agriculture. Salinity ranges 0.5 dSm-1 in monsoon and 50 dSm-1 in summer. Proper understanding about the nature, properties and prevailing constraints related to diverse group of coastal soils is necessary to undertake better management practices to improve the productivity and quality of such low productive salty soils.


2020 ◽  
Vol 19 ◽  
pp. 135
Author(s):  
F. K. Pappa ◽  
D. L. Patiris ◽  
G. Eleftheriou ◽  
C. Tsabaris ◽  
M. Kokkoris ◽  
...  

The anthropogenic radionuclide 137Cs is used as a valuable oceanographic tracer for the study of sea water masses identification and water movement. In the present work, 137Cs activity concentrations have been investigated in deep basins of Aegean Sea. Seawater samples were collected from five different sampling stations, during scientific oceanic campaigns from the period March to April 2008. The applied methodology was based on the adsorption of radiocaesium from dissolved AMP (Ammonium Phosphomolybdate Hydrate) in 20 L water samples. Moreover, during the pre- concentration procedure, the 134Cs was used as reference tracer for determining the chemical efficiency and consequently to measure the activity concentration in a High Purity Ge detector. In terms of vertical records, the activity concentration in the selected basins ranged between 3-8.5 Bq/m3, depending on the region and the depth of the basins. The higher concentration (8.5 Bq/m3) was found in the region between Lemnos Island and the narrows of Dardanelles. The maximum concentrations were observed at the North Aegean Sea basins, between 20 and 40 m of depth, caused by the water masses coming from the Black Sea. At the Cretan Sea the vertical activity concentration of 137Cs was homogeneous down to 2000 m depth, with an exception at the 800 m where it was decreasing significantly due to the transient deep-water masses from Adriatic Sea.


2020 ◽  
Vol 6 (1) ◽  
pp. 183
Author(s):  
Muhammad Irham Sahana ◽  
Roh Santoso Budi Waspodo

Seawater intrusion promotes the degradation of groundwater quality through excessive pumping activities or natural phenomena such as tidal floods which are popular with coastal areas. Pekalongan city is one of the areas affected by this phenomenon and was analyzed in this study with reference to the 1986 Ad Hoc Sea Water Intrusion (PAHIAA) Decree which classifies water into five based on salinity. This involved using the Integrated Distance Method (IDW) to map and applying the logarithmic equation to determine the dispersion relationship. The results showed seawater intrusion has already affected groundwater quality up to 6.52 km from the coastline for total dissolved solids and electrical conductivity and 7.22 km for chloride ion.  The distribution of TDS, EC, and Cl- in the freshwater zone was also recorded to have reached 28.59 km2, 28.36 km2, and 23.95 km2 respectively. It is predicted that in 4 years, there would no longer be freshwater in Padukuhan Kraton Village due to decreasing groundwater quality caused by seawater intrusion. Furthermore, 23.03 km2 Pekalongan area which spread into 4.34 km2 to the West, 0 km2 to the South, 14.39 km2 to the North, and 1.28 km2 to the East of the district has also been affected and was discovered to be caused mainly by tidal flood from Bremi and Tirto rivers. 


Author(s):  
Olga Mashukova ◽  
Olga Mashukova ◽  
Yuriy Tokarev ◽  
Yuriy Tokarev ◽  
Nadejda Kopytina ◽  
...  

We studied for the first time luminescence characteristics of the some micromycetes, isolated from the bottom sediments of the Black sea from the 27 m depth. Luminescence parameters were registered at laboratory complex “Svet” using mechanical and chemical stimulations. Fungi cultures of genera Acremonium, Aspergillus, Penicillium were isolated on ChDA medium which served as control. Culture of Penicillium commune gave no light emission with any kind of stimulation. Culture of Acremonium sp. has shown luminescence in the blue – green field of spectrum. Using chemical stimulation by fresh water we registered signals with luminescence energy (to 3.24 ± 0.11)•108 quantum•cm2 and duration up to 4.42 s, which 3 times exceeded analogous magnitudes in a group, stimulated by sea water (p < 0.05). Under chemical stimulation by ethyl alcohol fungi culture luminescence was not observed. Culture of Aspergillus fumigatus possessed the most expressed properties of luminescence. Stimulation by fresh water culture emission with energy of (3.35 ± 0.11)•108 quantum•cm2 and duration up to 4.96 s. Action of ethyl alcohol to culture also stimulated signals, but intensity of light emission was 3–4 times lower than under mechanical stimulation. For sure the given studies will permit not only to evaluate contribution of marine fungi into general bioluminescence of the sea, but as well to determine places of accumulation of opportunistic species in the sea.


Author(s):  
Vera Rostovtseva ◽  
Vera Rostovtseva ◽  
Igor Goncharenko ◽  
Igor Goncharenko ◽  
Dmitrii Khlebnikov ◽  
...  

Sea radiance coefficient, defined as the ratio of the sunlight reflected by the water bulk to the sunlight illuminating the water surface, is one of the most informative optical characteristics of the seawater that can be obtained by passive remote sensing. We got the sea radiance coefficient spectra by processing the data obtained in measurements from board a moving ship. Using sea radiance coefficient optical spectra it is possible to estimate water constituents concentration and their distribution over the aquatory of interest. However, thus obtained sea radiance coefficient spectra are strongly affected by weather and measurement conditions and needs some calibration. It was shown that practically all the spectra of sea radiance coefficient have some generic peculiarities regardless of the type of sea waters. These peculiarities can be explained by the spectrum of pure sea water absorption. Taking this into account a new calibration method was developed. The measurements were carried out with the portative spectroradiometers from board a ship in the five different seas: at the north-east coast of the Black Sea, in the Gdansk Bay of the Baltic Sea, in the west part of the Aral Sea, in the Kara Sea with the Ob’ Bay and in the Philippine Sea at the coast of Taiwan. The new method of calibration was applied to the obtained spectra of the sea radiance coefficient that enabled us to get the corresponding absorption spectra and estimate the water constituents concentration in every region. The obtained concentration estimates were compared to the values obtained in water samples taken during the same measurement cycle and available data from other investigations. The revealed peculiarities of the sea radiance coefficient spectra in the aquatories under exploration were compared to the corresponding water content and some characteristic features were discussed.


2018 ◽  
Vol 3 (2) ◽  
pp. 38-47
Author(s):  
Muhammad Abdul Azis ◽  
Nuryake Fajaryati

This research aims to create a Reosquido desalination tool for evaporation methods using a microcontroller. This tool can control the temperature to speed up the evaporation process in producing fresh water. The method applied to Reosquido desalination uses Evaporation. The first process before evaporation is the detection of temperature in sea water that will be heated using an element heater. The second process of temperature measurement is to turn off and turn on the Arduino Uno controlled heater, when the temperature is less than 80 ° then the heater is on. The third process is evaporation during temperatures between 80 ° to 100 °, evaporation water sticks to the glass roof which is designed by pyramid. Evaporated water that flows into the reservoir is detected by its solubility TDS value. The fourth process is heater off when the temperature is more than 100 °. Based on the results of the testing, the desalination process using a microcontroller controlled heater can speed up the time up to 55% of the previous desalination process tool, namely manual desalination prsoes without using the heater element controlled by the temperature and controlled by a microcontroller which takes 9 hours. Produces fresh water as much as 30ml from 3000ml of sea water, so that it can be compared to 1: 100.


2012 ◽  
Vol 16 (7) ◽  
pp. 1845-1862 ◽  
Author(s):  
F. Jørgensen ◽  
W. Scheer ◽  
S. Thomsen ◽  
T. O. Sonnenborg ◽  
K. Hinsby ◽  
...  

Abstract. Geophysical techniques are increasingly being used as tools for characterising the subsurface, and they are generally required to develop subsurface models that properly delineate the distribution of aquifers and aquitards, salt/freshwater interfaces, and geological structures that affect groundwater flow. In a study area covering 730 km2 across the border between Germany and Denmark, a combination of an airborne electromagnetic survey (performed with the SkyTEM system), a high-resolution seismic survey and borehole logging has been used in an integrated mapping of important geological, physical and chemical features of the subsurface. The spacing between flight lines is 200–250 m which gives a total of about 3200 line km. About 38 km of seismic lines have been collected. Faults bordering a graben structure, buried tunnel valleys, glaciotectonic thrust complexes, marine clay units, and sand aquifers are all examples of geological structures mapped by the geophysical data that control groundwater flow and to some extent hydrochemistry. Additionally, the data provide an excellent picture of the salinity distribution in the area and thus provide important information on the salt/freshwater boundary and the chemical status of groundwater. Although the westernmost part of the study area along the North Sea coast is saturated with saline water and the TEM data therefore are strongly influenced by the increased electrical conductivity there, buried valleys and other geological elements are still revealed. The mapped salinity distribution indicates preferential flow paths through and along specific geological structures within the area. The effects of a future sea level rise on the groundwater system and groundwater chemistry are discussed with special emphasis on the importance of knowing the existence, distribution and geometry of the mapped geological elements, and their control on the groundwater salinity distribution is assessed.


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