Analysis of Rainfall through Space - Time during 1999-2014 in Salem District, South India

The present study deals about the Rainfall assessment using various recent techniques with the help of remote sensing and GIS in Salem District, South India. The rainfall assessment carried over a period of 16 years from 1999 to 2014, which are clearly analyzed by using mean annual rainfall, mean seasonal rainfall, mean annual rainfall variability, mean seasonal rainfall variability, mean annual precipitation ratio and mean seasonal precipitation ratio methods. The methodology adopted based on literature study and which has given an accurate results. Therefore, the output shows that the study area has received 1 %, 19%, 41% and 39% of precipitation in winter, summer, southwest and northeast season respectively and the average annual rainfall is relatively more in N and NE and it is gradually decreases the eastern, western and southern parts of the study area. The rainfall variability indicates more than 100% in winter season except Nangavalli which is indicate the not dependable rainfall and other three season's rainfall variability less than 100% except Veeraganoor station, which is indicate the dependable rainfall available during these period. The precipitation ratio is less abnormality during SW and NE season and high abnormality during summer and winter season. Finally, rainfall variation assessment depicts that the rainfall conditions in Salem district is normal and fluctuation depends upon time and space

Lithological Discrimination of Anorthosite using ASTER data in Oddanchatram Area, Dindigul district, Tamil Nadu, India

The present study applies with hyperspectral remote sensing techniques to map the lithology of the Oddanchatram anorthosite. The hyperspectral data were subjected to Principal Component Analysis (PCA), Independent Component Analysis (ICA) and Minimum Noise Fraction (MNF), Pixel Purity Index (PPI) and n-Dimensional Visualization for better lithology mapping. The proposed study area has various typical rock types. The PCA, ICA and MNF have been proposed best band combination for effectiveness of lithological mapping such as PCA (R: G: B=2:1:3), MNF (R: G: B=4:3:2) and ICA (R: G: B=3:1:2). The derived lithological map has compared with published geological map from Geological Survey of India and validated with field investigation. Therefore, ASTER data based lithological mapping are fast, cost-effective and more accurate

Holocene climate variability and Indian Summer Monsoon: An overview

The response of the Indian Summer Monsoon (ISM) to forcing factors and climate variables has not yet fully explored, even though the ISM plays a pivotal role in the socio-economics of the Indian subcontinent and nearby areas. The ISM progression over Indian landmass is a manifestation of the Intertropical Convergence Zone (ITCZ) migration over the northern Indian Ocean and the Indian subcontinent. The recent anomalous behaviour of ISM raises the need for a better understanding of its spatio-temporal changes during the ongoing interglacial period termed as the Holocene period. The Holocene period has been classified further based on the globally observed abrupt climatic events at 8.2 and 4.2 ka. The 8.2 ka global cooling events have been recorded from northern Indian Ocean marine archives but limited records from the continental archives of the Indian landmass has demonstrated the 8.2 ka event. At the same time, the 4.2 ka dry climate has been endorsed by both marine as well as continental records and agrees with the global studies. During the ‘Little Ice Age’ (LIA), in the India subcontinent, wet conditions prevailed in the northern, central and western regions while a dry climate existed over the greater part of peninsular India. The present review offers an account of ISM signatures and possible mechanisms associated with the monsoon variability in the Indian subcontinent and the northern Indian Ocean during the Holocene period. </jats:p