R. Nagarajan

Spatio-temporal drought assessment in Tel river basin using Standardized Precipitation Index (SPI) and GIS

The spatial and temporal characteristics of droughts were investigated to provide a framework for agriculture practices, engineering facilities and sustainable water resources management in the Tel river basin which is about 2756 km2 and lies between 19°17′ and 20°00′N and 82°30′ and 82°59′E in Kalahandi district of Odisha, India. Using the Standardized Precipitation Index (SPI) as an indicator of drought severity for the period from 1965 to 2008, the characteristics of droughts were examined. The multiple-time scaled SPI values were evaluated for May–October months and point-wise indices were interpolated over the whole area using spatial interpolation technique in Arc GIS 9.2, in order to obtain areal extension of the drought severity. The results indicated that a dramatic and widespread drought event was recorded in the year 2002 at most of the stations and drought categories. However, regardless of the drought severity, an extraordinary dryness was experienced in the years 1966, 1972, 1979, 1987 and 2002 in the entire study area. It was observed that 10 years were successively dry during May at Jayapatna station from 1999 to 2008 in the 6-month drought category. The highest SPI value of −3.06 was observed in July 2002 in the Dharamgarh station in the 9-month drought category. The overall outcome of this study demonstrates that severe and extreme droughts were experienced from time to time across the study area leading to unfavourable results on agricultural practices and water resources in the area.

Synergistic use of orbital satellite image and ground-based information in environmental monitoring of railway alignment construction - a case study

Environmental monitoring of road/railway/highway alignment construction activity is necessary to assess the probable negative impacts on the physical, biological and hydrological environment. This would aid in assessing the effectiveness of mitigation measures proposed and executed measures. Multitemporal orbital remote sensing data along with site-based information on water and air quality and noise level were used in the environmental impact assessment (EIA) and auditing of Konkan railway alignment in India. This method of integrated data collection and analysis could be used effectively for monitoring similar projects elsewhere.

Environmental impact analysis of Dudhganga Dam in India - a multi-temporal remote sensing approach

Surface-cover status of the catchment, reservoir and dam site, before, during and after the completion of a water resources project, plays a vital role in an Environmental Impact Assessment (EIA). Orbital satellite data, along with theme and site-based information, were used in an EIA of Dudhganga Dam in India. The collection and analysis of these data in the monitoring of on-going projects is highlighted in this study.

Pre-and post-construction status of panam reservoir and its environs using remotely sensed and ancillary data

The success of water-resources projects can be evaluated by using remotely sensed and ancillary data supported by ground-based information. Surficial features in the vicinity of Panam reservoir of the Mahi-Kadana river-valley project, have been demarcated using IRS data of 1991 (post-commission) and 1969 topographic sheet information (prior to commission) and have been evaluated. Observed positive and negative changes indicate that the project maintains its environment-friendly function.

Reflectance characteristics of rocks in geological remote sensing

Surface and laboratory measured reflectance data of various rock types were analysed for the possible correlation with Landsat MSS response using statistical methods. It is found that band 6(0.7–0.8 μm) in field and satellite and band 7(0.8–1.1) in field and laboratory data have maximum correlation coefficient.

Glacial lake changes and outburst flood hazard in Chandra basin, North-Western Indian Himalaya

ABSTRACT Climatic change-induced glacier recession has been accompanied by formation and growth of proglacial lakes in the Himalayan region, which pose an emerging significant threat to the downstream communities/settlements in the form of outburst floods. To understand spatiotemporal evolution patterns, sources and driving mechanism of formation and expansion of glacial lakes, a temporal inventory of glacial lakes (area > 2000 m2) in Chandra basin has been developed from 2000 to 2014 using IRS LISS-III images. From 2000 to 2014, the total number of glacial lakes in Chandra basin increased from 28 to 46 and area expanded from 1.91 ± 0.24 km2 to 3.26 ± 0.24 km2. Glacier recession and increased glacier melt runoff due to climate warming led to the formation and expansion of glacial lakes in space vacated by glacier recession. The increase in number and area of ice-dammed lakes at higher elevations confirms the continued glacier retreat in the basin. Lakes in contact or in the proximity of the mother glacier exhibit higher growth and formation rate. The accelerated growth of glacial lakes has resulted in increased hazard and damage potential of glacial lake outburst floods in Chandra basin. Seven potentially dangerous lakes are identified and analysed qualitatively for outburst probability.

Combating Agricultural Drought in Developing Countries through Watershed Approach: A Case Study from Odisha, India.

Periodic drought affects both developing and the developed countries around the globe with direct impacts on agriculture and on other productive sectors reliant on water. However, it is in developing countries, where drought is highly correlated with the performance of the overall economy, as a result of heavy reliance on agriculture. India is amongst the most vulnerable drought prone countries in the world, where a drought has been reported at least once in every three years in the last five decades. An attempt has been made in this paper to provide a comprehensive idea of drought through interpretation and correlation of various drought causative parameters. As a state or even a district is too large a unit with varying covers, soil types, crop types, etc., the sub basin level assessment has been considered for the detailed drought assessment in this study. The Tel watershed covering an area of 2756 km2 and lies between 19° 17 and 20° 00 N latitude and 82° 30 and 82° 59E longitude near Bhawanipatna region of Kalahandi district of Odisha, India was selected as the study area. Spatiotemporal variation of seasonal drought patterns and drought severity in the Tel watershed was analyzed by the Standardized Precipitation Index (SPI) using GIS based interpolation. Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI) were generated to understand the impact of precipitation deficiency on vegetation vigor and growth. The analysis shows that drought assessment by watershed approach and the combination of various parameters can offer better understanding and better monitoring of agricultural drought conditions in developing countries.

Synergetic use of active and passive remotely-sensed and map data in the delineation of part of Godavari palaeocourse

Abstract Map information for ( 1937-38 and 1965-66) Indian Remote Sensing Satellite (IRS) data of October 1988 and 1990, Landsat-TM data of 1987 and airborne SAR data ( 1988) were used in the identification of river course, geomor-phological features and palaeo channels over part of the Godavari river, India. The change in river course and growth and erosion of the island/ sand bar were measured. The palaeocourse of the river at test sites has been reconstructed. The measured cut-off ratio indicates that the chute cut-off of the river course near Gannavaram is very high. Flood affected areas in the regions could be assessed by this method.

Regional engineering geological mapping using remotely sensed data

Landsat MSS 7 and False Colour composite were interpreted in the delineation of regional geomorphology, geology, structural and vegetational cover. Mass and material characteristics of the rocks were incorporated in the preparation of an engineering geological map. A net work of road alignments has been proposed based on the Geotechnical Feasibility Index.RésuméDes clichés Landsat MSS 7 et fausses couleurs ont servi à linterprétation des caractéristiques géomorphologiques, géologiques et à létude de la végétation. Les caractéristiques des roches rencontrées ont également été prises en compte pour la cartographie géotechnique. Des tracés routiers ont été proposés en tenant compte de lensemble des données géotechniques.