Geosciences Research

14

Authors: Alok Kumar Mishra, Anil Kumar

Assessment of rainfall trend and monitoring meteorological drought and wet conditions are very important in dealing with agricultural planning and water resources management under the influence of changing climate in the Himalayan region. This study was conducted to assess rainfall trend and monitor the drought and wet pattern at four stations, namely Naula, Kedar, Chaukhutia and Mehalchauri, located in the upper Ramganga River catchment in Uttarakhand state of India in the central Himalayan region. Rainfall trend analysis at these stations was carried out using Mann-Kendall test and Sen’s slope estimator. Standardized Precipitation Index (SPI) at multiple time scales of 1-, 3-, 6-, 9-, 12- and 24-months was used to assess meteorological drought and wet pattern at Naula station. Results have indicated a significantly downward trend in December and post-monsoon season and an upward trend in September at Naula station. Significantly downward trend was also observed in July, December and monsoon season at Kedar station, and in June, July, August, monsoon and annual data series at Chaukhutia station. No significant trend was observed at Mehalchauri station. Study also revealed that there are more chances of occurrences of mild drought and wet conditions and only meager chances of moderate drought and wet conditions during monsoon season. However, the chances of severe and extreme drought and wet conditions are almost negligible. Therefore, efforts must be made to harvest the excess water during the wet periods and utilize the same during the periods of mild and moderate drought for drinking, household activities and irrigation purposes.

7

Authors: Ashutosh Kainthola, Dhananjai Verma, T N Singh

Hill stations which are favoured tourist destinations are mostly accessible by road excavated on the hill slopes. These roads cut slopes pose a grave threat to life and local economics in case of a slope failure. Proper study is called for to mitigate this danger of these slope failures which are especially rampant during the rainy season. In the present study a road cut slope along SH-72 near Mahableshwar, Maharashtra, India, has been numerically simulated using finite element and finite difference techniques to appraise their stability under dry and saturated conditions.

12

Authors: Baljeet Singh

In the present work, a problem on the reflection of elastic waves at a plane surface of an elastic half-space is considered. The elastic half-space is assumed homogeneous and isotropic. The plane surface of half-space is subjected to impedance boundary conditions, where normal and tangential tractions are proportional to normal and tangential displacement times frequency, respectively. The reflection coefficients of reflected P and SV are obtained in closed form for incidence of P or SV waves. These reflection coefficients depend on the angle of incidence, impedance parameters and other material parameters. The material parameters of Diabase (dark-colored igneous rock), Limestone (sedimentary rock) and Gneiss (high grade metamorphic rock) are chosen to compute the reflection coefficients for certain ranges of angle of incidence and impedance parameters. The effect of impedance boundary on the reflection phenomena is shown graphically for three different rock materials (Diabase, Limestone and Gneiss).