Rationale: The small river basins in the narrow stretch of the Arabian Sea coast of southwest India experience high annual rainfall (800-8000 mm), with a higher proportion (85 %) during the summer monsoon period between June and September. This is due to a unique orographic barrier provided by the Western Ghats mountain belt (600-2600 m) for the summer monsoon brought by the southwesterly winds. This study is the first of a kind focusing on the water cycle with an intensive stable isotopes approach (samples of river water, groundwater, rainwater; seasonal and spatial sampling) in this part of the Western Ghats in Karnataka and also in the highest rainfall-receiving region (with places like Agumbe receiving 7000-8000 mm annual rainfall) in South India. In addition, the region lacks sustainable water budgeting due to high demographic pressure and a dry pre-monsoon season as the monsoon is mainly unimodal in this part of India, particularly close to the coast.
Methods: The stable isotopic compositions of groundwater, river water and rainwater in two tropical river basins situated approximately 60 km apart, namely the Swarna near Udupi and the Nethravati near Mangalore, were studied from 2010 to 2013. The δ(18)O and δ(2)H values of the water samples were measured by isotope ratio mass spectrometry, and the d-excess values calculated to better understand the dominant source of the water and the influence of evaporation/recycling processes.
Results: The water in the smaller area basin (Swarna basin) does not show seasonal variability in the δ(18)O values for groundwater and river water, having a similar mean value of -3.1 ‰. The d-excess value remains higher in both wet and dry seasons suggesting strong water vapor recycling along the foothills of the Western Ghats. In contrast, the larger tropical basin (Nethravati basin) displays specific seasonal isotopic variability. The observation of higher d-excess values in winter with lower δ(18)O values suggests an influence of northeast winter monsoon water in the larger basin.
Conclusions: The narrow coastal strip to the west of the Western Ghats displays unique water characteristics in both tropical river basins investigated. For the smaller and hilly Swarna basin, the dense vegetation (wet canopies) could largely re-evaporate the (intercepted) rain, leading to no marked seasonal or altitude effect on the water isotope values within the basin. The larger Nethravati basin, which stretches farther into the foothills of the Western Ghats, receives winter monsoon water, and thus exhibits a clear seasonal variability in rainfall moisture sources. The degree of water vapor recycling in these wet tropical basins dominates the isotopic composition in this narrow coastal stretch of South India. An insight into the soil water contribution to the river water and groundwater, even in the rainfall-dependent tropical basins of South India, is provided in this study.
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http://dx.doi.org/10.1002/rcm.7424 | DOI Listing |
Sci Data
December 2024
Centre for Climate Change Research, Indian Institute of Tropical Meteorology, Ministry of Earth Sciences, Pune, India.
High-frequency precipitation (solid/liquid) isotope datasets are useful for identification of moisture sources and various dynamical and thermodynamical processes controlling precipitation formation. Here, we report three-year (2019-2021) daily rain isotope (both oxygen, δO hereafter, and hydrogen, δH, hereafter) datasets from three unique locations in India during the Indian Summer Monsoon (ISM). The locations are- (1) Port Blair- an island situated in the Bay of Bengal (BoB); (2) Mahabaleshwar, located at the crest of the Western Ghats Mountain; and (3) Tezpur, in northeast India, situated close to a dense forest.
View Article and Find Full Text PDFMycoscience
August 2024
b Department of Botany, Bajaj College of Science.
A new species, , was described from the tropical region of the Western Ghats of Maharashtra, India based on morphological characteristics and molecular phylogenetic analysis. is characterised by its yellowish brown to reddish brown granular scales on the pileus, stipe apex exudes colourless drops, broadly ellipsoid to ellipsoid to ovoid basidiospores, clavate to cylindrical, catenulate cheilocystidia with subglobose to cylindrical ante-terminal elements. Further, the molecular markers nrITS and nrLSU sequence data analyses of with their sister taxa revealed the distinct phylogenetic position of the new species.
View Article and Find Full Text PDFMicrosc Res Tech
December 2024
Department of Botany, Bharathiar University, Coimbatore, India.
Vincetoxicum capparidifolium (Wight & Arn.) Kuntze [=Tylophora capparidifolia (Wight & Arn.) Kuntze], belonging to the family Apocynaceae, is a medicinal plant species endemic to the southern Western Ghats, Tamil Nadu, India.
View Article and Find Full Text PDFNat Prod Res
December 2024
Department of Chemistry, Ramnarain Ruia Autonomous College, Matunga, Mumbai, India.
This study explores the anticancer properties of , a plant indigenous to the Western Ghats of India. We isolated and characterised 5-hydroxy-7-methoxy-8-O-β-D-glucopyranosyl-2S-flavanone from , previously unreported in this plant, using preparative HPLC, NMR, and HRMS techniques. The compound's molecular structure and purity were confirmed, and its biological activity was evaluated on the MDA-MB-231 breast cancer cell line using the MTT assay.
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