Identification of groundwater recharge sites and suitable recharge structures for Thuraiyur taluk using Geospatial technology

2117-2125This study is an attempt to identify the favorable zones for implementation of site-specific artificial recharge techniques for groundwater resources development. Various thematic layers such as base map, geology map, soil map and drainage map were prepared from toposheets and existing maps. Satellite data were used to prepare other layers such as geomorphology, landuse/ land cover, lineament. Water level, rainfall maps were prepared using collateral data. All these layers were integrated into GIS platform and get the artificial recharge zonation map and it was categorized into four different zones, namely ‘most favorable 20%’, ‘moderately favorable 22%’, ‘favorable 34%’ and ‘least favorable 24% ’

Geoscientific study to locate hydrocarbon prospective zones in a part of Cauvery Basin using Remote Sensing and GIS techniques

1447-1453IRS-P6 LISS III geocoded FCC data in conjunction with Survey of India toposheets (1:50,000) and field inputs were used for thematic mapping. Geomorphic units identified through visual interpretation of FCC include: fluvio-marine sediments, flood plain, coastal plain, beach ridges, swale and palaeo-channels. In addition, lineaments were also mapped. Based on the geomorphology, geology, DEM, subsurface faults and lineaments hydrocarbon prospective zones in a part of Cauvery Basin has been identified. The demarcated prospective zones were compared with the gravity and magnetic data as well as topographical and structural maps

Decadal evolution of a spit in the Baram river mouth in eastern Malaysia

We studied a newly formed spit in the Baram River mouth in Eastern Malaysia and evaluated the effects of climatic conditions and human interference over the last four decades (1974-2014). The development of a spit during a decade (1998-2008) and its maximum expansion over the period 2005-2010 is related to the erosion associated with deforestation and land use changes in the upstream region. The downstream transportation of the heavy sediment load occurred during the events of higher precipitation and flash floods. The recent spit was identified for the first time as a mud flat post the flash flooding of January 2005. It extended towards the south west of the river mouth till 2010 (six fold increase in area from 2005 to 0.29km<sup>2</sup>) and gradually disintegrated over the next 3 years. Depositional feature of coarse sediments and organic debris is clearly supported by the alternating thick layers in the top 25cm of the three core samples (C1-C3) collected from the region. The non-existence of finer particles clearly indicates the supremacy of long shore currents in the region carrying away the fines to deeper regions. Gradual disappearance of the sand barrier post 2011 is due to the reduction in the amount of sediment load as a result of reduction in recent rainfall activity, land use/land cover changes mainly as reforestation, strengthening of palm plantation (controlling soil erosion in the river banks) in the upstream region. The dominant NW wind direction during the major part of the year is also one of the factors for the shift in depositional sequence and it is helped by the long shore currents which lead to the spit being partially connected to the main land

Depositional environment of sediments along the Cuddalore coast of Tamilnadu, India

375-382Surficial sediments of beaches along the Cuddalore, central coast of Tamilnadu from Ponnaiyar estuarine to Thirumulaivasal were studied for their textural parameters namely Mean (Grain size) phi, Standard deviation, Skweness and Kurtosis and mineral percentages. Observed variation of energy conditions are controlled by the fluvial profile in the river channel. Textural analysis of medium sand shows the existence of comparatively high energy condition in the marine environment and low energy conditions in the fluvial zone. Linear Discriminant Function (LDF) analysis of the samples indicates a shallow marine environment origin for most of the samples and very few numbers of samples originated from fluvial environment. Heavy mineral content serves as an index for stratigraphic correlation of unfossilferrous strata. The lowest heavy mineral content indicates progradational activity and low energy wave conditions. These results show that reworked sediments, submerged during the Holocene marine transgression are being deposited on present day beaches by waves, currents and rivers in the study region. </span

On the urgent vulnerability assessment of the Coromandel coast of India threatened by increasing and combined environmental and human pressures

International audienc

Fine-scale assessment of changes in zonations of species for the management of imperiled mangroves, Pichavaram, India

International audienceEach mangrove region has a specific history which needs to be understood as it is a central component for adapting current conservation plans to changing coastal conditions induced by increasing natural or human pressures. As these latter impact the functioning, physiognomy and extent of mangroves, it is urgent to design and implement monitoring programs able to monitor changes in zonations of mangrove species (ZMS). Recent studies highlighted the combined potential of very high spatial resolution (VHSR) satellite images and robust field data to map such mangrove areas dominated by a few species.Here we examined the Pichavaram mangroves, southeast coast of India. The 1100-ha mangrove wetland area was, in 1987, declared to be a Forest Reserve by the Forest Department, Government of Tamil Nadu. Disturbances generated by the 2004-tsunami, decreasing freshwater, and increasing pollutants inflow, combine to modify the geochemistry of the whole region with a potential influence on the zonation of mangrove species. Afforestation programmes have been carried out since the 1980s using the fishbone canal-bank technique.We inventoried species and measured trunk diameters (DBH), tree heights within forest plots representative of a large range of planted and natural ZMS. Based on this ground expertise, we performed a spectral and textural analysis of five VHSR multispectral images acquired between 2003 and 2018 to generate ZMS maps on a scale of 1:2000. Our results indicate that mangrove cover is increasing while species richness decreases in favour of salt-tolerant species. Our analysis also highlights a shrunk in average tree crown size, suggesting alterations in species succession and plant growth capability. We thank the Tamil Nadu Forest Department for allowing us to undertake this study