Impact of the 2004 Sumatran tsunami on the diversity of intertidal brachyuran assemblages of Maavah, Laamu Atoll, Maldives

A 2-year spatio-temporal survey of intertidal brachyuran crabs involving five sites was conducted in the Maavah reef system, Laamu Atoll, Maldives, from April 2001 to March 2003. In December 2004, the sites were hit by the catastrophic Sumatran tsunami. An 8-month-long study was carried in the same five sites after the tsunami, and the data obtained were compared with the pre-impact baseline data. A sand dune formed at the north-eastern side of the island as a result of the tsunami was also included in the post-tsunami study (site 6). Nine brachyuran crab species not recorded during pre-tsunami sampling in the five study sites were collected after the event. Of these, six species were recorded in site 6 during January 2005, and they started to appear in the other sites in the following months. Nine species of crabs collected during the pre-tsunami periods from four sites were not represented in the post-tsunami collections. Abundance, evenness and diversity of the post-tsunami brachyuran communities of sites 1 and 2 exhibited downward trends, and the evenness and diversity of the post-tsunami communities of site 4 exhibited upward trends when compared with pre-tsunami patterns. Multivariate analyses revealed that the tsunami had changed the post-tsunami brachyuran communities of sites 1?C4. However, tests revealed that in site 4, the pre-tsunami brachyuran assemblage 1 (2001?C2002) differed from pre-tsunami assemblage 2 (2002?C2003) and post-tsunami assemblages. The roles of tsunami-transported species and site-specific dominant species in contributing to faunal dissimilarities between the pre- and post-tsunami brachyuran assemblages were found to be patchy. Further studies would reveal whether the population of any newly added species increases or decreases in the long term.     

Radioelement geochemistry of alkali granites of the Kerala region,south-west India

Th, U and K abundances in four alkali granites of the Kerala region, south-west India, are presented. The plutons show high radioelement levels, correlatable with those of alkali granites in other regions. The nature of variation is consistent with the correlation of Th and U with accessory phases like sphene, zircon, allanite, apatite and monazite. A geochronologic correlation is also observed between the alkali granites and the Th-bearing beach placers of the region. The petrogenetic features of the alkali plutons, their taphrogenic association, Pan-African affiliation and high Th/U levels suggest that the alkali plutons are favourable locales for radioelement exploration.     

A model of the subsidence history of the West Coast of India

The occurrence of earthquakes all along the West Coast of India and in the Arabian Sea is explained systematically in terms of the interaction between the underthrusting Indian ocean floor and the Indian subcontinent. This north ward compression due to the repeated underthrusting of the oceanic floor has caused the formation of trenches, grabens and normal faults on the continental margin.     

Numerical simulation of cloud burst event on August 05, 2010, over Leh using WRF mesoscale model

Localized deep cumulus convective clouds have a capability of giving enormous amount of rainfall over a limited horizontal area, within a short span of time. Such types of extreme rainfall events are most common over the high elevated areas of Northern India during the Southwest monsoon season which causes widespread damage to the property and lives. Therefore, it is necessary to predict such extreme events accurately to avoid damage associated with them. The numerical mesoscale model Weather Research and Forecasting has been used to simulate the cloud burst event of Leh on August 05, 2010, so as to capture the main characteristics of the various parameters associated with this localized mesoscale phenomenon. The model has been integrated with four nested domains keeping Leh and its adjoining area as center. Two cloud microphysics parameterization schemes namely WSM3 and WSM6 have been used for the sensitivity experiments and results have been analyzed to examine the performance of both the schemes in capturing such extreme localized heavy rainfall events. Results show that the WSM6 microphysics was able to simulate the precipitation near to the observation. WSM3 microphysics simulated the location of the circulation near to the observation. In addition, the results also show that the maximum magnitudes of meridional and vertical wind as simulated with WSM3 microphysics are 12 and 4 m/s, respectively.     

Groundwater simulation studies of parts of Western Yamuna Canal Command area, Haryana for planning sustainable development

A single layer mathematical model was developed to simulate the hydrogeological condition and groundwater flow in an area of about 2536 Sq km, which forms part of the WYC Command area. The model was run both for the steady state and for the transient state. The model was then successfully calibrated. The calibration results were recorded qualitatively and quantitatively. The results of the calibrated model were analyzed. Two Scenarios developed alonwith six scenarios created earlier, in another modeling study, were analyzed to find out a sustainable solution for optimal utilization of surface and ground water. The two Scenarios developed show that a viable solution will be reduction in pumping and regulated surface water supply. This will ameliorate water logging in the nearby areas. The reduction in pumping and thereby, reduction of return flow recharging groundwater can be achieved by improving water use efficiency and modifying/changing cropping pattern. These strategies can be successfully implemented, through mass awareness programmes, involving the farmers, who have to implement the programme, along with all the other stake holders. Ultimately reduction of groundwater pumping can be achieved through strict groundwater regulation. Direct recharge by way of seepage through canal can be reduced by lining the unlined canals and proper repair and maintenance of the already lined canals. But this has to be tested through a pilot project vis-a-vis economic viability of this lining, as seepage may be indirectly helping groundwater recharge in areas without water logging. Further to increase the availability of surface water and augment recharge of groundwater, the surface run off from the precipitation, can be utilized in various ways to reduce to decline of groundwater level.     

Spectroscopic study of rocks of Hutti-Maski schist belt,Karnataka

Recent developments in sensor technology have given an onset for studying the earth surface features based on the detailed spectroscopic observation of different rocks and minerals. The spectroscopic profiles of the rocks are always quite different than their constituent minerals however, the spectral profile of a rock can be broadly reconstituted from the spectral profile of each constituent minerals. Interpretation of rock spectra using the spectra of constituent minerals based on relative spectral matching can bring out interesting information on the rock. Present study is an effort toward this and it highlights how visible-near infrared-shortwave-infrared (VNIR-SWIR) rock spectroscopy acts as an useful tool for understanding the rock-mineralogy in indirect and rapid way. It has also been observed that spectral signatures of rocks; studied in present case, are related to spectral signatures of constituent minerals although absorption features of constituent mineral in the rock are also modified by the other minerals juxtaposed in the rock fabric. However, each rock of the study area has their significant absorption features, but many of the absorption signatures are closely spaced, as altered rock has significant absorption at 2305 nm whereas amphibolite has its important absorption signature in 2385 nm and metabasalt has its significant absorption at 2342 nm. Therefore spectral measurement of high spectral resolution with appreciable signal to noise ratio (SNR) only can detect rocks from each other based on the absorption signatures mentioned above (each of which is 10 to 20 nm apart from the other) and therefore spectroscopy of rock is an innovative technique to map rocks and minerals based on the spectral signatures.