Geomorphic expression of late Quaternary sea level changes along the southern Saurashtra coast, western India

Geomorphic expression of land-sea interaction is preserved in the form of abandoned cliffs, marine terraces, shore platforms and marine notches along the southern Saurashtra coast. These features have been used to ascertain the magnitude of sea level changes during late Quaternary. Notch morphology and associated biological encrustation have been used to estimate the magnitude and duration of palaeo-sea strands. Marine notches and other erosive features occurring between 12 and 15 m above the present Biological Mean Sea Level (BMSL) are attributed to the last interglacial corresponding to the Marine Isotopic Stage 5 (MIS-5). However, 6 to 9 m upliftment of the coastal fringe is attributed to this sea level. The second major high sea strand was identified during the mid-Holocene when the sea rose 2 m above the present level. Notches corresponding to this high sea level are recorded 4 to 5 m above the present BMSL.     

Morphotectonic analysis in Anandpur Sahib area,Punjab (India) using remote sensing and gis approach

Anandpur Sahib area of Rupnagar district (Punjab) was investigated using an integrated multi-disciplinary approach of geomorphological, structural, drainage and morphotectonic analysis through satellite data and GIS. Most commonly used geomorphic indices viz., channel sinuosity, drainage basin asymmetry, basin elongation ratio, mountain front sinuosity and valley floor to valley width ratio index have been used to identify the geomorphic indicators of active tectonics in the area. Existence of fluvial anomalies viz., abrupt changes in flow direction, flow against gradient, beheaded streams and river terraces reflect the strong structural control on the fluvial features. Asymmetric nature of drainage basin, elongated nature of the sub-watersheds, straight to curvilinear mountain fronts and narrow incised valley floors further substantiate the role of active tectonics in the region.     

Coastal boulders as evidences of high-energy marine events from Diu Island,west coast of India: storm or palaeotsunami?

Natural Hazards - The coastal segment of Diu Island from west coast of India has been studied for its boulder deposits. The dimensions, morphology and characteristics of these boulders were studied...     

Assessment of reproductive potential of different populations of <Emphasis Type="Italic">Angelica glauca</Emphasis> Edgew., a critically endangered Himalayan Medicinal Herb

Angelica glauca is one of the important medicinal plants and it is widely used by indigenous communities for different purposes. The present study analyzes variability in reproductive characters of A. glauca. The reproductive parts were found having significant positive correlation with altitude （e.g.,number of umbellets /umber r= 0.857,p〈0.05; umbel diameter r=0.735,p〈0.05）.     

Effects of fluctuating daily surface fluxes on the time-mean oceanic circulation

The effect of fluctuating daily surface fluxes on the time-mean oceanic circulation is studied using an empirical flux model. The model produces fluctuating fluxes resulting from atmospheric variability and includes oceanic feedbacks on the fluxes. Numerical experiments were carried out by driving an ocean general circulation model with three different versions of the empirical model. It is found that fluctuating daily fluxes lead to an increase in the meridional overturning circulation (MOC) of the Atlantic of about 1 Sv and a decrease in the Antarctic circumpolar current (ACC) of about 32 Sv. The changes are approximately 7% of the MOC and 16% of the ACC obtained without fluctuating daily fluxes. The fluctuating fluxes change the intensity and the depth of vertical mixing. This, in turn, changes the density field and thus the circulation. Fluctuating buoyancy fluxes change the vertical mixing in a non-linear way: they tend to increase the convective mixing in mostly stable regions and to decrease the convective mixing in mostly unstable regions. The ACC changes are related to the enhanced mixing in the subtropical and the mid-latitude Southern Ocean and reduced mixing in the high-latitude Southern Ocean. The enhanced mixing is related to an increase in the frequency and the depth of convective events. As these events bring more dense water downward, the mixing changes lead to a reduction in meridional gradient of the depth-integrated density in the Southern Ocean and hence the strength of the ACC. The MOC changes are related to more subtle density changes. It is found that the vertical mixing in a latitudinal strip in the northern North Atlantic is more strongly enhanced due to fluctuating fluxes than the mixing in a latitudinal strip in the South Atlantic. This leads to an increase in the density difference between the two strips, which can be responsible for the increase in the Atlantic MOC.     

HAND (height above nearest drainage) tool and satellite-based geospatial analysis of Hyderabad (India) urban floods,September 2016

Urban flooding needs to be understood holistically and addressed geospatially by all stakeholders. In the present study, an attempt is made to understand the problem of urban flooding in part of Hyderabad city (Zone-12) geospatially considering the satellite-based changes in land use/land cover between 1989 and 2016, identifying low-lying areas vulnerable to flooding using HAND (height above nearest drainage) model in conjunction with the analysis of high-resolution satellite images and ground based validation of affected locations during rains of September 2016. The study shows that Zone-12 has undergone significant increase in impervious cover by 42% between 1989 and 2016. The impact of urbanization has obliterated the footprints of stream network, significantly changing the hydrological landscape due to burial of channels and concretization of lake beds. The interconnected channel network and lake system acting as sinks to absorb high runoff during monsoons have been encroached upon aggravating the urban flooding problem. The study shows that HAND model can be an effective tool under data scarce environments, limited cloud-free high-resolution satellite data availability during floods to have first cut baseline information on flood vulnerable areas.     

X-ray emission from O-type stars: DH Cep and HD 97434

We present X-ray emission characteristics of the massive O-type stars DH Cep and HD 97434 using archival XMM-Newton observations. There is no convincing evidence for short-term variability in the X-ray intensity during the observations. However, the analysis of their spectra reveals X-ray structure being consistent with two-temperature plasma model. The hydrogen column densities derived from X-ray spectra of DH Cep and HD 97434 are in agreement with the reddening measurements for their corresponding host clusters NGC 7380 and Trumpler 18, indicating that the absorption by stellar wind is negligible. The X-ray emission from these hot stars is interpreted in terms of the standard instability-driven wind-shock model.     

Geo-environmental appraisal of the Meda creek,Saurashtra, Gujarat

Water chemistry, sediment texture, clay mineralogy and foraminiferal contents from the bottom of Meda creek were studied to assess the geo-environmental status of the creek. Water quality data for three seasons suggests domination of marine environment as pH remained above 8 and salinity above 35‰ throughout. Clay dominate the bottom sediments, except near mouth. Montmorillonite, illite and kaolinite are the major clay minerals in the sediments. In absence of any source rock in the catchment of the Meda creek, the presence of illite and kaolinite indicates their transportation and depositions from near coastal waters during high tides. Ammonia sp. is the most dominating foraminifera. Reworked forms as well as angular asymmetric forms of foraminifera were dominant in clay rich areas of the creek.