Environmental isotopes investigation in groundwater of Challaghatta valley, Bangalore: A case study (original) (raw)
Related papers
Journal of Hydrology, 2011
Groundwater degradation through abstraction, contamination, etc., shows a worldwide increase and has been of growing concern for the past decades. In this light, the stable isotopes of the water molecule (δ 18 O and δ 2 H) from a hard-rock aquifer in the Maheshwaram watershed (Andhra Pradesh, India) were studied. This small watershed (53 km 2) underlain by granite, is endorheic and representative of agricultural land use in India, with more than 700 bore wells in use. In such a watershed, the effect of overpumping can be severe and the environmental effects of water abstraction and contamination are of vital importance. A detailed and dynamic understanding of groundwater sources and flow paths in this watershed thus is a major issue for both researchers and water managers, especially with regards to water quality as well as the delimitation of resources and long-term sustainability. To this end, the input from monsoon-precipitation was monitored over two cycles, as well as measuring spatial and temporal variations in δ 18 O and δ 2 H in the groundwater and in precipitation. Individual recharge from the two monsoon periods was identified, leading to identification of periods during which evaporation affects groundwater quality through a higher concentration of salts and stable isotopes in the return flow. Such evaporation is further affected by land use, rice paddies having the strongest evapotranspiration.
Variation of stable isotopes in groundwater of Tezpur (Assam)
2012
Isotope techniques are effective tools for satisfying critical hydrologic information needs like the origin of groundwater, recharge, residence time, impact of climate change on water resources, interconnections between water bodies, among others. Isotopes provide information that sometimes could not be obtained by other techniques. Stable and radioactive environmental isotopes have now been used for more than four decades to study various aspects of hydrological systems. Stable isotopes are very useful tools which are used extensively in scientific research. Within the field of nutritional studies stable isotopes are used for studying the flow of nutrients through the human body. Since they are safe and non-radioactive they can even be used in infants and pregnant women. In the present study a comprehensive set of measurements of hydrogen and oxygen isotopic composition (2H‰ and 18O‰) taken from a variety of locations for the first time to determine the Local Ground Water Line (LGW...
The groundwater samples from different aquifers (shallow, intermediate and deep) were collected from Jalandhar and Kapurthala districts, Punjab and analysed for major ions, stable isotopes of oxygen and hydrogen and environmental tritium activity. The groundwater in shallow and intermediate aquifer is Ca-Mg-HCO 3 and in deep aquifer is Na-HCO 3 hydro geochemical facies. The groundwater chemistry in the study area is influenced by silicate dissolution of host rock. The shallow aquifer shows recharge is mainly through local precipitation. Location around R. Beas show significant contribution from the river. The Bist-Doab canal shows very less contribution to shallow aquifer. The enriched nature of isotopic composition in the shallow aquifer is mainly due to evaporation of water during filtration through impermeable clayey layer. The groundwater in deep aquifer gets recharged mainly from the precipitation from outside the study area.
Journal of Bangladesh Academy of Sciences, 2014
Groundwater of Chapai Nawabganj town has been studied using hydrogeological, hydrochemical and environmental isotope (?18O, ?2H, ?13C, 3H and 14C) data. Aquifer underneath the study area is divided into unconfined to semi-confined Holocene alluvial floodplain aquifer and confined Plio-Pleistocene Dupi Tila sandstone aquifer. Chemical composition of groundwater is characterized by high concentrations of Mg2+, Na+, Ca2+, HCO3-, FeTotal, and low concentrations of Mn2+, NO3 - and PO4 3-. Groundwater samples are mainly Mg-Ca-HCO3 and Na-Mg-Ca-HCO3 types and Na-Mg-Ca-Cl-HCO3 type of water is also found at some places. Based on Cl- and SO42- concentrations groundwater is normal chloride and normal sulphate water, respectively. In terms of SAR and EC values water is excellent for irrigation purpose. The isotopic composition also suggests some segregation of groundwater from the different aquifers and indicates different ages of recharge. DOI: http://dx.doi.org/10.3329/jbas.v38i2.21338 Journ...
2021
In many Asian megacities, millions of human inhabitants are dependent on groundwater for fulfilling daily water demand due to lack of public water supply and infrastructure. Many of these megacities are situated on alluvial plains which are more susceptible to contamination also. The present study has been carried out in Jhajjar District, Haryana, a part of Indo-Gangetic Plain, India. Indo-Gangetic plain, harbour one of the most productive alluvial aquifer of the world and plays an important role in Indian economy. After green revolution, in a large part of Indo-Gangetic plain groundwater salinization and contamination has been reported. In past few decades, groundwater in Jhajjar district is continuously degraded by fluoride, sulphate, chloride, salinity, etc. problems. So, the present study aims to assess the groundwater quality of the alluvial aquifer of Jhajjar district using integrated approach. Hydrochemistry in integration with stable isotopes (δ18O and δD), GIS and multivari...
In the present study, to demonstrate use of combined isotopic and salinity mapping in understanding local scale groundwater-surface water conditions the water samples were collected from 4 nos. of defined lakes (Kadaba, Belavatta, Pura and Nittur); groundwater samples were collected from shallow hand pumps/tube wells along the periphery of the lakes. The rain samples were also collected. The lake water appears to get enriched in its isotopic composition mainly due to evaporation in this region. Lake water salinities are lower compared to nearby groundwater salinity. The flow of groundwater, recharged at Nittur lake, continues to its downstream at least till Pura. Increase in salinity of groundwater is seen between the points Pura-groundwater & surface water (may be due to dissolution of sub-surface soil). The groundwater sampled at Belavatta is found to be recharged from local precipitation and not from surface body. The water body (Kadaba) is getting filled mainly due to precipitation and to some extent due to runoff from the upper reach of water body. There is a strong link between lake water-groundwater (e.g. site Pura) and groundwater-lake water (e.g. Site Kadaba). Therefore, this procedure is expected to radically increase the accountability of usage and help in planning of suitable ground water supply and would provide a holistic approach to promote maximum agricultural output and industrial growth.
Groundwater flow system in Bengal Delta, Bangladesh revealed by environmental isotopes
Your article is protected by copyright and all rights are held exclusively by Springer-Verlag. This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to self-archive your work, please use the accepted author's version for posting to your own website or your institution's repository. You may further deposit the accepted author's version on a funder's repository at a funder's request, provided it is not made publicly available until 12 months after publication. Abstract A total number of 328 groundwater samples are analysed to evaluate the groundwater flow systems in Bengal Delta aquifers, Bangladesh using environmental isotope ( 2 H, 18 O, 13 C, 3 H, and 14 C) techniques. A welldefined Local Meteoric Water Line (LMWL) d 2 H = 7.7 d 18 O ? 10.7 % is constructed applying linear correlation analyses to the monthly weighted rainfall isotopic compositions (d 18 O and d 2 H). The d 18 O and d 2 H concentrations of all groundwater samples in the study area are plotted more or less over the LMWL, which provides compelling evidence that all groundwaters are derived from rainfall and floodwater with a minor localized evaporation effects for the shallow groundwaters. Tritium concentration is observed in 40 samples out of 41 with values varying between 0.3 and 5.0 TU, which represents an evidence of young water recharge to the shallow and intermediate aquifers. A decreasing trend of 14 C activity is associated with the heavier d 13 C values, which indicates the presence of geochemical reactions affecting the 14 C concentration along the groundwater flow system. Both vertical and lateral decrease of 14 C activity toward down gradient show the presence of regional groundwater flow commencing from the unconfined aquifers, which discharges along the coastal regions. Finally, shallow, intermediate, and deep groundwater flow dynamics has revealed in the Bengal Delta aquifers, Bangladesh.
Journal of Applied Geochemistry, 2016
Aurangabad located in the heart of drought-prone interior of Maharashtra State, India is one of the major urban centers in the Deccan sub-region. The Chikalthana area of Aurangabad is selected to assess the effect of seasonal variation in groundwater quality on irrigation and human health. The entire study area is covered by the Deccan Trap lava flows of upper Cretaceous to Eocene age. Groundwater samples were collected from forty five locations during pre-monsoon and post-monsoon seasons and were analysed for pH, EC, TDS, TH, Ca ++ , Mg ++ , Na + , K + , CO-3 , HCO-3 , Cl-, and SO-4. Suitability of groundwater for irrigation was evaluated based on sodium adsorption ratio (SAR), soluble sodium percentage (SSP), residual sodium carbonate (RSC), US salinity Laboratory's and Wilcox's diagram which suggests that 16% of groundwater samples from the study area is not fit for irrigation purposes both in pre-and post-monsoon seasons indicating that the area is affected by a salinity hazard zone. Comparison of groundwater quality in relation to drinking water quality standards with BIS (2005) proves that most of the groundwater samples are not suitable for drinking purposes and that there is an urgent need to reduce pollution levels before it becomes unmanageable.
Environmental Earth Sciences, 2012
Hydrogeological and climatic effect on chemical behavior of groundwater along a climatic gradient is studied along a river basin. 'Semi-arid' (500-800 mm of mean annual rainfall), 'sub-humid' (800-1,200 mm/year) and 'humid' (1,200-1,500 mm/year) are the climatic zones chosen along the granito-gneissic plains of Kabini basin in South India for the present analysis. Data on groundwater chemistry is initially checked for its quality using NICB ratio (\±5 %), EC versus TZ? (*0.85 correlation), EC versus TDS and EC versus TH analysis. Groundwater in the three climatic zones is 'hard' to 'very hard' in terms of Ca-Mg hardness. Polluted wells are identified ([40 % of pollution) and eliminated for the characterization. Piper's diagram with mean concentrations indicates the evolution of CaNaHCO 3 (semi-arid) from CaHCO 3 (humid zone) along the climatic gradient. Carbonates dominate other anions and strong acids exceeded weak acids in the region. Mule Hole SEW, an experimental watershed in sub-humid zone, is characterized initially using hydrogeochemistry and is observed to be a replica of entire sub-humid zone (with 25 wells). Extension of the studies for the entire basin (120 wells) showed a chemical gradient along the climatic gradient with sub-humid zone bridging semi-arid and humid zones. Ca/Na molar ratio varies by more than 100 times from semi-arid to humid zones. Semi-arid zone is more silicaceous than sub-humid while humid zone is more carbonaceous (Ca/Cl *14). Along the climatic gradient, groundwater is undersaturated (humid), saturated (subhumid) and slightly supersaturated (semi-arid) with calcite and dolomite. Concentration-depth profiles are in support of the geological stratification i.e., *18 m of saprolite and *25 m of fracture rock with parent gneiss beneath. All the wells are classified into four groups based on groundwater fluctuations and further into 'deep' and 'shallow' based on the depth to groundwater. Higher the fluctuations, larger is its impact on groundwater chemistry. Actual seasonal patterns are identified using 'recharge-discharge' concept based on rainfall intensity instead of traditional monsoonnon-monsoon concept. Non-pumped wells have low Na/Cl and Ca/Cl ratios in recharge period than in discharge period (Dilution). Few other wells, which are subjected to pumping, still exhibit dilution chemistry though water level fluctuations are high due to annual recharge. Other wells which do not receive sufficient rainfall and are constantly pumped showed high concentrations in recharge period rather than in discharge period (Anti-dilution). In summary, recharge-discharge concept demarcates the pumped
spatialhydrology.com
Integrated geohydrological, isotopes and Geographical Information System (GIS) techniques have been used to delineate groundwater resources potential in the Piedmont zone of Himalayan foothill region, Uttaranchal, India. Thematic maps for hydrogeomorphology, slope, and drainage density have been prepared and integrated with the help of GIS by assigning the weights to various attributes controlling occurrence of groundwater to generate the groundwater potential map for the study area. The results indicates that the southern part of the study area has very good groundwater potential whereas the steeply sloping area in the northern part having high relief and high drainage density possesses poor groundwater potential. The groundwater potential zones are found in agreement with the available yield data of tubewell. Vertical component of recharge to groundwater due to precipitation varies from 3 to 13 %, which has been estimated using Tritium Tagging Technique. The estimated recharge to groundwater shows a linear relationship with environmental tritium contents in the water samples. This indicates that the precipitation is the major source of recharge in the study area. On the basis of environmental tritium contents, it has been found that recharge to groundwater is taking place at higher altitudes (300-400m, AMSL) in the Bhabhar region where the shallow and deeper aquifers have good interconnection. The estimated groundwater flow rate for the deeper aquifer is 1.2 m/d. The groundwater flow pattern estimated from isotope techniques has been validated from flow pattern determined by the depth of groundwater table.