Evaluation of groundwater potential zones using Remote Sensing data in upper Vaigai river basin,Tamil Nadu,India

The area of upper Vaigai river basin covering parts of Madurai and Theni Districts, in Tamil Nadu, faces acute water scarcity and chronically drought prone. The groundwater resources in the area have not been fully exploited. The present investigation has been made to evaluate the potential zones for groundwater targeting using IRS - ID LISS III geocoded data on 1:50,000 scale. The geology, geomorphology, lineament tectonic maps are generated and integrated to evaluate the hydrogeomorphological characteristics of the upper Vaigai river basin and demarcate the groundwater potential zones. A number of geomorphic units have been observed. Out this the more groundwater prospective units are buried pediment medium, buried pediment deep, flood plain, bajada and lineament and intersection of lineaments. Non potential areas like pediment, pediment inselberg, shallow pediment and pediplain were identified.     

Structure and its impact in Uthangarai and Thirthamalai region, Tamil Nadu, India using remote sensing technique

The Uthangarai-Thirthamalai region in Dharmapuri district is a typical Precambrian tract in Tamil Nadu. IRS-1C satellite imagery was used for interpreting folds, faults, fractures and lineaments, in this region. As interpreted from the satellite imagery, there are five major structural domains, which control the Ponnaiyar, Pambar, Vaniyar and Kovilar river courses and other drainage pattern in this region. Presence of fault rock, epidotization and sympathetic fractures along such folds and faults reveals the intensity of tectonism in this sector. The interpreted lineaments have been classified into five major groups on the basis of their geometry and orientation. From the rose diagram, it is inferred that the NNW-SSE trending lineaments are fall in major frequency domain. The springs observed near Hanumanthirtham and Thirthamalai region could be structurally originated. The geomorphology interpreted from the satellite data has shown significant morphological expression of folds, faults and lineaments. The geophysical data have been analysed and correlated with intensity of weathering by fractures and lineaments.     

Aid of remote sensing in mapping geofractures of environmental significance in Tamil Nadu

Geofractures play a crucial role in environmental degradation and environmental pollution. Such geofractures were interpreted using LANDSAT and IRS 1A imagery and integrated with seismic, erosion and groundwater-chemistry data. The study shows that mostly the N-S and NE-SW trending fractures are prone to seismicity and pollutant migration while NE-SW and WNW-ESE trending faults are prone to soil erosion. The study further shows that mostly the Quaternary fractures/lineaments and the Quaternary reactivated Precambrian fractures are having a dominant control over such phenomena. On the basis of such studies, suggestions are made to take adequate care while dealing with such regions for resource exploitation and developmental purposes.     

Remote Sensing of suspended sediments along the Tamil Nadu coastal waters

Indian Remote Sensing satellite (IRS) 1A & 1B digital data in combination with field measurement were used to map distribution and concentration of suspended sediments along the Tamil Nadu coastal waters for monsoon and non-monsoon periods. Qualitative suspended sediment mapping was done for entire Tamil Nadu coast while quantitative studies were taken at two selected sites (eg. Tuticorin and Ennore). For qualitative mapping both monsoon (17-12-90) and non-monsoon (18-4-90) season data were analysed by level slicing technique and a qualitative scale was assigned to different sediment classes based on tonal variations. The suspended sediment concentration (SSC) samples were collected on April 15, 1992 and March 10, 1992 around Ennore and Tuticorin coastal waters respectively, synchronous to IRS-1A satellite overpass. This data was used for quantitative estimation of SSC using digital chromaticity technique. The study shows that the plumes of high suspended sediment concentration are contributed from the nearshore wetlands and river mouths and were finally dispersing towards Jaffna coast. Different classes of high to low SSC values ranging from less than 5 mg/L in offshore areas to 21 mg/L in nearshore of Tuticorin were also delineated. The dispersal pattern of the sediments on different is discussed.     

Impact of tsunami on aquaculture farms along the nagapattinam coast zone,Tamil Nadu,India

The tsunami waves triggered by underwater earthquake with a focal depth of 30 km near the Sumatra Island distressed the entire coast of Tamil Nadu. The worst affected coastal region is Nagapattinam, particularly from Nagoore to Vailankanni. The impact of tsunami had multidimensional effect, killing most of the fishermen communities, devastating the coastal huts and damaging the coastal aquaculture resources. The present study has been carried out to find the impact of tsunami on the aquaculture small farmland owners along the coast using pre (December 18, 2004) and post January 6, 2005) IRS P6 data. The study includes the extent of damage caused to the farms by saltwater intrusion; sand inundation, total destruction of farms. The results indicate that, there have been incredible damage caused to the farmers beyond recovery in short span of time.     

Dynamics of coastal landform features along the southern Tamil Nadu of India by using remote sensing and Geographic Information System

This article reveals an application of multi-spectral satellite data for analysing the dynamics of different coastal landform features along the southern coastal Tamil Nadu of India. An integrated approach comprising visual image interpretation and maximum-likelihood supervised classification has been employed to classify the coastal landforms by using IRS data (during the period 1999–2006). The quality of image classification has been assessed by performing the accuracy assessments with the existing thematic maps and finally the coastal landforms have been mapped. The study reveals that the dynamics of coastal landforms such as sandy beaches, mud-flats, sand dunes and salt marshes along the study area are mostly influenced by the coastal processes, sediment transport, geomorphology and anthropogenic activities. Major anthropogenic sources for the perturbation of beach sediment budgets and a cause of beach erosion along the study area are excessive sand mining, removal of sand dunes, coastal urbanization, tourism and developmental activities.     

Ground Water Quality Maps of Paravanar River Sub Basin,Cuddalore District,Tamil Nadu,India

Ground water is an excellent solvent, which dissolves chemicals ions as it moves through rocks and subsurface soil. This leads to more mineralization in groundwater than surface water. The objective of the present study is to examine the groundwater quality of the Paravanar River Sub-basin, Cuddalore district, Tamil Nadu, India. The Electrical Conductivity (EC) values ranges between 160 and 2,580 μS/cm in groundwater samples. The highest value of 2,580 μS/cm was recorded in wells near the coast. pH values ranges from 7.2 to 8.6. NNE and southern part of the study area has low pH values, rest of the area represents the alkaline nature of groundwater. In south eastern part of the study area alkali values are slightly higher but it is within WHO’s tolerable limits. The spatial distribution of chloride concentration shows that Meenatchipettai, Vazhisothani palayam and Allapakkam represents maximum Cl₂ concentration of 527, 320 and 374 ppm, which is above ISI drinking standards of 250 ppm. Increase in isochlore is observed from the coast up to the Neyveli lignite mine. Nitrate concentration of groundwater samples ranges from 0.1 mg/l to 64 mg/l. As most of the study area is cultivated, fertilizers used for agriculture may be the cause for increase in concentration of nitrates in few concentrated locations.     

Flood intensity and land evaluation in the Cauvery delta,Tamil Nadu,applying modern remote sensing techniques

An area of about 7500 km² covering Cauvery delta has been studied from airphotos (1:60,000), Landsats (1:250,000) and survey of India topographic sheets (1:50,000) with a view to delineate various landforms, soils, land use, hydromorphic units, drainage, and flood intensity of the delta. The delta is composed of mainly ancient channels, delta p ains, fossil islands, levees, beach ridges, mangroves marshes and coastal dunes. The various soil types are clayey soils, silty soils, silty loams, sandy loams, coastal sands and alkaline clays. Paddy and sugarcane are dominant crops. The old channels are found to be zones of high ground water potential. The growth of delta seems to be from south to north with twelve abandoned meander lobes and three delta fronts with gradual influx of material into Bay of Bengal. The old rivet courses lying parallel to the present active Coleroon river in third stage of the growth of the delta seem to be severely affected by floods. Moderate to low growth is noticeable in the second stage of the of the delta. The oldest river course which debouched into Bay of Bengal near Adirama-patnam is less affected by floods. The delta plains, fossil islands, disturbed ridges and beach ridges are unaffected. Basing on landforms, soils, land use, hydrogeomorphology and flood intensity the land capability of the delta has been evaluated. About seven classes of land are interpreted.     

Geology and geomorphology of Cumbum valley and Varushanadu hills,Madural district,Tamil Nadu through remote sensing

The Varushanad hills forms the eastern offshoot of the Western Ghats and the Cumbum valley divides the Varushnad hills from the Western Ghats. Investigations were carried out in about 1700 sq Km comprising the Cumbum valley and the Varushanad hills of the Western Ghats situated in Periakulam Srivalliputhur and Usilampatti taluks of Tamil Nadu on the geological and geomorphological aspects. Remote sensing techniques were used and limited field checks were made. Visual interpretation of aerial photographs on 1:60,000 scale was carried out for identifying the geomorphological features, drainage pattern and lithology. Digital analysis of the Landsat computer compatible tape (CCT) path-row 154–053 was also carried out to delineate major lithological variations. Major lineaments were also mapped from the Landsat imagery and false colour composite. The rock types of the Cumbum valley and the Varushanad hills are mainly charnockites, granite gneiss and pink granites which have been deformed by folds and faults. The various geomorphological units of the area are ridges, valleys, bazada zone and pediment zone of mountain complex. Resources evalution studies on the potential zone of ground water and possible construction materials were also discussed.     

Geomatics Based Analysis of Predicted Sea Level Rise and its Impacts in Parts of Tamil Nadu Coast,India

The coastal zones around the world are very densely populated and hence heavily packed with related infrastructures. So, the territorial nations have obvious apprehensions against the IPCC SRES (Intergovernmental Panel on Climate Change, Special Report on Emission Scenario) predicted sea level rise, as it would cause flooding of the low lying coasts and also other related chains of environmental endangers. This has driven these nations to initiate research studies in multiple directions for scientifically evaluating the phenomenon and impacts of sea level rise using all possible technologies including the Geomatics which possesses unique credentials in geosystem mapping. But certain advanced virtues available with Geomatics technology are yet to be capitalized deservingly in this. In addition, almost all the earlier studies have focused only on the impacts of sea level rise (SLR) and not on the predicted shift of high tide line (HTL) and the related inter tidal activities, which would cause a series of environmental disaster. Hence, the present research study was undertaken in a test site of 750 km² in central Tamil Nadu coast to visualize the areas prone to submergence due to predicted SLR and areas prone to environmental disasters/degradation viz. erosion, deposition, salination of agricultural lands, pollution of aquifers, etc. due to predicted shift of HTL, using digital elevation models derived from SRTM data (Shuttle Radar Topographic Mission), geomorphology and land use/cover maps interpreted using IRS P6 LISS IV satellite data. The paper narrates the certain newer concepts and methodologies adopted in the study and the results.     

Geoinformatic Modeling of Groundwater Resource Mapping of Shear Zone Regions- A Case Study on Attur Valley,Tamil Nadu,India

The general tendency of mapping groundwater resource using remote sensing and Geographic Information System (GIS) techniques involve assigning higher weightage to geomorphology. But this cannot be used as a thumb rule everywhere, especially an area where many ductile and brittle zones are prevalent. The influence of texture and structure of sheared rocks might play a control over retaining and permitting groundwater to flow. Attur valley is characterized by the presence of many shear zones and faults and hence the rocks are highly fissile within the shear zones. The present study tries to establish a new ranking and weightage scheme and hence a new spatial model for groundwater resource mapping in shear zone area like Attur Valley. This spatial model can be verified with field data such as water level data, pump test and resistivity data.     

Geological remote sensing in parts of subarnarekha — baitarani basin,Eastern India

Landsat imagery have been interpreted visually and under Additive Colour Viewer to interpret the regional geology and geomorphology in parts of Subarnarekha-Baitarani basin. The area lies south of Singhbhum shear zone and represents Precamrain shield. Important Simlipal ultrabasic volcanic complex of Orissa is included in the area. Although detailed map of the area is available, yet an attempt has been made to interpret the imagery for evaluating the results provided in comparison to the existing maps. Delineation of main lithological groups is possible. Having some data from the existing maps, lithoiogical boundary delineation of Mica Schist-Phyllite-Quartzite, Granites and Gneisses, Dhanjori Lava, Anorthosite-Gabbro Complex and Dolerite dykes, all of Precambrian age, has been done. Laterite and Quaternary sediments are also picked up. Lineament mapping has been carried out from imagery, which is difficult to map in the field. N--S and NNW-SSE lineament system is very prominent in Simlipal complex whereas in other parts NNW-SSE and NNE-SSW trends are common. The major fault plane running NNE-SSW in the area is responsible for the present-day configuration of Subarnarekha river. Identification of different geomorphological units is perhaps best done on imagery. Several geomorphic units like structural Hill, Denudational Hill, Pediment, Buried Pediment, Lateritic Clay Plain, Laterite upland, Terrace Plain etc have been mapped. Valley fills are wellpicked up from imagery. Hydrogeological potentiality of the different geologic and geomorphic units have been evaluated qualitatively. Ground water occurrence, movement and potentiality are mainly controlled by structural, geological and geomorphological set-up of the area. Buried Pediment, Laterite upland, Laterite clay plain and alluvial fills are the potential zones from the view point of ground water occurrences. Comparative study of the different Landsat bands and band-filter combinations under Additive Colour Viewer has been undertaken to find out the enhancement capability in delineating features. It is found that small scale geological and geomorphological maps can be prepared from Landsat imagery.     

Prioritisation of sub-watersheds based on earth observation data of agricultural dominated northern river basin of India

The Upper Tons River Basin of North India has been selected for prioritisation of sub-watersheds (SW) based on morphometric parameters with respect to groundwater derived from topographic sheets and CARTOSAT data. There are 10 SW have been delineated in the region, high stream frequency (F_s) values of SW (1–5) and SW-9 indicated the occurrence of steep slopes, less permeable rocks, greater runoff, less infiltration possibility. Further, these regions have been predicted as poor groundwater potentialities. SW-2 has been identified as poorest groundwater potential zone, whereas SW-4 and SW (6–8) regions possess good permeable bed rocks. The Drainage density (D_d) map demonstrated that the middle south-west region possesses higher D_d whereas northeastern regions contain lower D_d. Further, the areal parameters indicate elongated shape of the basin, hilly region has moderate to steeper ground slope. The outcomes of work have potential to manage groundwater and to ameliorate the flash flood and droughts.     

Saline degradation of Indian agricultural lands : A case study in Khambhat Taluka,Gujarat state (India), using satellite remote sensing

In certain agricultural fields of Khambhat Taluka in Gujarat State, the salinity has increased considerably rendering the land completely infertile. The occurrence of salinity in this area can be attributed partly to subsurface sea‐water ingress and partly to improper land and water management practices prior to implementation of irrigation. Landsat MSS or TM and IRS IA LISS II data was used to test the feasibility of delineating saline soils by both visual image interpretation and digital analysis. The study of saline soils using multi‐temporal Landsat images of the year 1977, 1983, and 1987, indicated an evident increase in saline areas in past few years. The Soil Brightness Index (SBI) generated from the IRS‐IA data by the application of MSS equivalent coefficients brought out different categories of soil degradation. The supervised classification scheme aided in generating various salinity levels. The analysis of the soil samples of the above area exhibited increasing values of Electrical Conductivity (ECe), and the soluble cations with increasing levels of salinity.     

A combined deficit index for regional agricultural drought assessment over semi-arid tract of India using geostationary meteorological satellite data

The untimely onset and uneven distribution of south-west monsoon rainfall lead to agricultural drought causing reduction in food-grain production with high vulnerability over semi-arid tract (SAT) of India. A combined deficit index (CDI) has been developed from tri-monthly sum of deficit in antecedent rainfall and deficit in monthly vegetation vigor with a lag period of one month between the two. The formulation of CDI used a core biophysical (e.g., NDVI) and a hydro-meteorological (e.g., rainfall) variables derived using observation from Indian geostationary satellites. The CDI was tested and evaluated in two drought years (2009 and 2012) within a span of five years (2009–2013) over SAT. The index was found to have good correlation (0.49–0.68) with standardized precipitation index (SPI) computed from rain-gauge measurements but showed lower correlation with anomaly in monthly land surface temperature (LST). Significant correlations were found between CDI and reduction in agricultural carbon productivity (0.67–0.83), evapotranspiration (0.64–0.73), agricultural grain yield (0.70–0.85). Inconsistent correlation between CDI and ET reduction was noticed in 2012 in contrast to consistent correlation between CDI and reduction in carbon productivity both in 2009 and 2012. The comparison of CDI-based drought-affected area with those from existing operational approach showed 75% overlapping regions though class-to-class matching was only 40–45%. The results demonstrated that CDI is a potential indicator for assessment of late-season regional agricultural drought based on lag-response between water supply and crop vigor.     

Groundwater prospects evaluation-based on hydrogeomorphological mapping: A case study in Kancheepuram district,Tamil Nadu

Water is the most important natural resource which forms the core of the ecological system. The advent of remote sensing has opened up new vistas in groundwater prospect evaluation, exploration and management. The role of hydrogeomorphological units in tile storage of groundwater from the Kancheepuram distict has been investigated using IRS P6 LISS-III data. The Kancheepuram district exhibits diverse hydrogeomorphological conditions where the groundwater regime is controlled mainly by topography and geology. The extent of various water prospectus zones in terms of percentage includes, maximum area, particularly the north-western, and central part which is characterized by good potential occupying about 43% of total area. The moderate potential is marked by only 35%, and is scattered along the northern and southern side of the study area, the remaining 12% is of poor prospectus, which is falling in the coastal region of the study area.     

Predicting agricultural drought in eastern Rajasthan of India using NDVI and standardized precipitation index

In the present study, prediction of agricultural drought has been addressed through prediction of agricultural yield using a model based on NDVI-SPI. It has been observed that the meteorological drought index SPI with different timescale is correlated with NDVI at different lag. Also NDVI of current fortnight is correlated with NDVI of previous lags. Based on the correlation coefficients, the Multiple Regression Model was developed to predict NDVI. The NDVI of current fortnight was found highly correlated with SPI of previous fortnight in semi-arid and transitional zones. The correlation between NDVI and crop yield was observed highest in first fortnight of August. The RMSE of predicted yield in drought year was found to be about 17.07 kg/ha which was about 6.02 per cent of average yield. In normal year, it was 24 kg/Ha denoting about 2.1 per cent of average yield.     

利用GPS反射信号遥感全球海态

最近几年，迅速发展一种新的空基海洋遥感技术。它在低轨卫星上接收经海面或地面反射的GPS信号，通过分析C／A或P码的相关函数波形及其后沿，荻得全球海面平均高度、浪高、海面风场以及土壤湿度等，提供海洋中尺度涡旋发展、演变信息，监测和分析高纬地区冰层厚度。它采用无源探测方法，具有成本低、荻取数据量多和快速等突出特点，是传统卫星高度计探测的重要补充和发展。该文讨论了这项技术发展现状、反射信号的时间延迟以及海态参数计算等关键技术；也给出作者利用掩星观测资料分析得到的海面反射回波一些重要结果。