DINESH KUMAR
Articles written in Journal of Earth System Science
Volume 121 Issue 2 April 2012 pp 439-451
A P Singh O P Mishra Dinesh Kumar Santosh Kumar R B S Yadav
We analyzed 3365 relocated aftershocks with magnitude of completeness (
Volume 128 Issue 5 July 2019 Article ID 0132 Research Article
GIS-based prediction of groundwater fluoride contamination zones in Telangana, India
Kiran Kumar Reddy S Dinesh Kumar Sahadevan Harish Gupta Dontireddy Venkat Reddy
Groundwater is the only perennial water resource available to rural communities, especially in semi-arid regions. This study aims to provide an overview of fluoride-contaminated groundwater in the Telangana, India, by predicting potentially affected areas. The prevalence of endemic fluorosis in different parts of Telangana has been widely reported. Therefore, it is necessary to demarcate the fluoride-affected areas to adopt the remedial measures. In this context, the available information on related environmental variables such as geological settings, hydro-morphological inputs, climatic information and soil properties have been integrated as thematic layers in an ArcGIS environment. The thematic layers and their features were assigned with suitable weights, which were normalised using the analytic hierarchy process to obtain final ranks and the weighted overlay analysis method was carried out to delineate the potential fluoride contamination (PFC) zones. The entire state was classified into four broad categories, i.e., very high (17.6%), high (15.8%), medium (32.7%) and low (33.9%), in terms of groundwater fluoride enrichment. A comparison of the output map and the reported data indicates that the PFC zone model could explain 68.7% of fluoride variation. This study is the first such attempt to offer a regional-scale PFC zone for an entire state and offers a first-hand insight into the severity of fluoride contamination.
Volume 129 All articles Published: 10 January 2020 Article ID 0044 Research Article
TAUFIQUE WARSI V SATISH KUMAR DEWASHISH KUMAR M J NANDAN GEORGE BISWAS DINESH KUMAR SAHADEVAN C MANIKYAMBA T VINODA RAO R RANGARAJAN SHAKEEL AHMED V CHANDRASEKHAR
A comprehensive geophysical and petrological study was carried out at Giddalur area in Prakasam district, Andhra Pradesh, which is geologically a highly deformed area and is difficult to delineate the aquifer zone(s). The task was to find out the exact rock type in which aquifer is concealed as well as to delineate the aquifer zone, which can yield sufficient quantity of water. The resistivity models derived from geophysical dataset were interpreted in terms of hydrogeology and the results revealed substantial resistivity contrast of the geological formations within the study area. We have delineated two major groundwater potential zones based on this study. These zones were tapped at different depths in diverse rock types. Drilled hand specimens (rock cuttings) were not adequate, so these specimens were petrographically studied to reveal the exact contact zones of the rock type. On integration of the geophysical and the petrographic results, it was illustrated that two aquifer zones were struck at a depth of 92 and 122 m between shale-phyllite and phyllite-quartzite, respectively. These findings were correlated, which matched with the lithology of the drilled borehole. This integrated approach will be helpful in strategy for groundwater assessment as well as prospecting groundwater resources in different geological terrain.
Volume 129 All articles Published: 13 November 2020 Article ID 0229 Research article
Estimation of Coda Q for northeast India using nonlinear regression
Classical logarithmic linearization of the single backscattering model to estimate the coda Q ($Q_{c}$) leads to biased results in the presence of low signal-to-noise ratio. Non-linear regression using the Levenberg–Marquardt (L–M) method has been proposed to estimate the $Q_{c}$ in the frequency range of 3–24 Hz on local earthquakes recorded in northeast region of India. Results of both classical log-linear and non-linear approaches to the single backscattering model are compared. On datasets with good signal-to-noise ratio both the approaches lead to almost the same results. However, for datasets having low signal-to-noise ratio, we found that the log-linear technique estimates are biased. Results demonstrate that the log-linear approach overestimates the $Q_{c}$ in comparison to the non-linear approach. Frequency dependence parameter ‘${\eta}$’ for the L–M method is slightly higher than the conventional log-linear approach. The $Q_{c}$ variation with lapse-time is also studied with both the approaches. The biased results of log-linear approach were observed at different frequencies at all lapse times. Significantly lower $Q_{0}$ (1 Hz) estimates of non-linear approach indicated more heterogeneous lithosphere than the log-linear approach.
$\bf{Highlights}$
$\bullet$ A novel approach to the single scattering model is proposed wherein nonlinear regression is performed to estimate coda $Q_{c}$.
$\bullet$ Coda attenuation and its variation with lapse time is analysed (3–24 Hz) from local earthquakes of North East India
$\bullet$ For datasets having a low signal-to-noise ratio the estimates of the conventional log-linear regression were biased.
$\bullet$ Significantly lower $Q_{0}$ estimates of the non-linear approach indicated a more heterogeneous lithosphere than a log-linear approach.
Volume 129, 2020
All articles
Continuous Article Publishing mode
Click here for Editorial Note on CAP Mode
© 2021-2022 Indian Academy of Sciences, Bengaluru.