Change detection of linear features in temporally spaced remotely sensed images using edge-based grid analysis

Automatic change detection of land cover features using high-resolution satellite images, is a challenging problem in the field of intelligent remote sensing data interpretation, and is becoming more and more effective for its applications viz. urban planning and monitoring, disaster assessment etc. In the present study, a change in detection approach based on the image morphology that analyses change in the local image grids is proposed. In this approach, edges from both the images are extracted and grid wise comparison is made by probabilistic thresholding and power spectral density analysis for identifying change area. One of the advantages of the proposed methodology is that the temporal images used in the change analysis need not be radiometrically corrected as analysis is based on edge extractions. The grid-based analysis further reduces the error, which might have been introduced by image mis-registration. The proposed methodology is validated by finding the temporal changes in the linear land cover features in parts of Kolkata city, India using three different image data-sets from LISS IV, Cartosat-1 and Google earth having varied spatial resolutions of 5.8 m, 2.5 m and about 1 m, respectively. The overall accuracy in identifying changes is found to be 64.82, 73.86 and 80.93% for LISS IV, Cartosat-1 and Google earth data-set, respectively.     

A comparative analysis of pansharpening techniques on QuickBird and WorldView-3 images

Nowadays, different image pansharpening methods are available, which combine the strengths of different satellite images that have different spectral and spatial resolutions. These different image fusion methods, however, add spectral and spatial distortions to the resultant images depending on the required context. Therefore, a careful selection of the fusion method is required. Simultaneously, it is also essential that the fusion technique should be efficient to cope with the large data. In this paper, we investigated how different pansharpening algorithms perform, when applied to very high-resolution WorldView-3 and QuickBird satellite images effectively and efficiently. We compared these 27 pansharpening techniques in terms of quantitative analysis, visual inspection and computational complexity, which has not previously been formally tested. In addition, 12 different image quality metrics available in literature are used for quantitative analysis purpose.     

Preparation of volume table of SAL (Shorea robusta) - an approach using satellite data

Sal (Shorea robusta) is an important forest tree species in north and north-eastern India. Large-scale plantations of this species have been raised there under taungya and coppice system of management. The conventional volume table prepared for high sal forest is referred to infer the volume of production of this species. Earlier workers have used aerial remote sensing data to develop volume tables of this species. In the present study a volume table for sal is developed based on remotely sensed satellite data using a regression technique. A two-step method was developed to estimate mean tree volume from satellite data. In step 1, mean crown diameter — an intermediate variable - was estimated from satellite data. In step 2, the estimated mean crown diameter was used to estimate the mean tree volume. Addition of age of the crop as an independent variable improved the predictive ability of the regression equation.     

Assessment of the biological quality of riverine water using pathogenicity islands (PAIs) of coliform bacteria as pollution indicator

The biological methods of quality assessment of water include the determination of harmful biological entities. In this study, quality of water from two riverine study sites was monitored in terms of the most probable number (MPN index) and pathogenicity. MPN index was found to be 0.11 and 0.15/100 mL which was also confirmed by membrane filtration technique (MFT). The isolated pure cultures were subjected to various pathogenicity tests including blood haemolysis and biofilm formation. Out of ten isolates, six showed positive results and these potentially pathogenic isolates were found to be resistant to various antibiotics like erythromycin (E), vancomycin (VA), chloramphenicol (C), tetracyclin (TE), acidoclav (AC) and kanamycin (K). Genetic analysis of these six isolates confirms the presence of flanking regions of virulence cassettes pathogenicity island (PAI) in their genome. Hence, in addition to the MPN test, the pathogenicity tests using the amplification of flanking regions of PAI can be used as a marker for determination of biological quality of water.     

Natech or natural? An analysis of hazard perceptions,institutional trust,and future storm worry following Hurricane Harvey

Natural Hazards - Researchers have traditionally conceptualized hazards that give rise to disasters as “natural” or “technological.” An extensive literature has documented...     

Disaster experience,social capitals,and behavioral health

On April 20, 2010, the Deepwater Horizon oil rig exploded, and oil spilled from the breached well-head for months, leading to an unprecedented environmental disaster with implications for behavioral health. Disasters are thought to affect behavioral health, and social capital is thought to ameliorate behavioral health impacts after disasters, though empirical evidence is mixed. One possible explanation for the discrepancy in findings relates to the activation of social capital in different contexts. In a disaster context, certain types of social capital may be more beneficial than others, and these relationships could differ between those directly affected by the disaster and those who are unaffected. The goal of this study is to assess the relationships between different forms of social capital (community engagement, trust, and social support) on different behavioral health indicators (depression, anxiety, and alcohol misuse) using data from the first wave of the Survey of Trauma, Resilience, and Opportunity among Neighborhoods in the Gulf (STRONG), a probabilistic household telephone survey fielded 6 years after the onset of the Deepwater Horizon oil spill (DHOS). We employ a structural equation modeling approach where multiple social capital and behavioral health variables can be included and their pathways tested in the same model, comparing the results between those who reported experiencing disruptions related to the DHOS and those who did not. Among those who experienced the DHOS, social support was negatively associated with both depression (β?=???0.085; p?=?0.011) and anxiety (β?=???0.097; p?=?0.003), and among those who did not experience the DHOS, social support was positively associated with alcohol misuse (β?=?0.067; p?=?0.035). When controlling for the other social capital variables, social support was the only form of social capital with a significant relationship to behavioral health, and these relationships differ based on whether or not a person experienced the disaster. This suggests that social capital does not have a uniformly ameliorative relationship with behavioral health in the aftermath of disasters.

     

Hydrochemistry and sediment characteristics of polar periglacial lacustrine environments on Fisher Island and Broknes Peninsula,East Antarctica

Fisher Island and Broknes Peninsula in the Larsemann Hills constitute part of a polar lowland periglacial environment between marine and glacial ecosystems. The landscape is characterized by gently rolling hills and broad valleys interspersed with lakes formed in glacially scoured basins. We analyzed the physieochemical parameters and the ionic constituents of water samples from 10 lakes in each of these two locations. Our results showed considerable differences between the two regions and demon- strated the influence of lithology and processes including weathering, evaporation, and atmospheric precipitation. All major cations and anions in the lake waters showed positive correlations indicating balanced ionic concentrations. Unconsolidated sediments were sparsely distributed and scattered over glacial deposits, valley fills, and occasional moraine ridges. The type and rate of sedi- mentation was mainly controlled by surface run-off and aeolian influx. The sediment samples from lake beds and the catchment area on Fisher Island were immature and poorly to very poorly sorted, consisting of gravelly sand with negligible silt and finer fractions. Sediments had a polymodal grain size distribution with the two major populations lying between -2 and 1 phi and be- tween 0 and 1.5 phi. The sediments were lithic arenite to arkosic in composition and the microtextures imprinted over quartz grains were dominated by mechanical textures resulting from several stages of glacial crushing and grinding. The presence of deep disso- lution cavities, cryptocrystalline precipitation, and euhedral crystal growth signified the effect of chemical activity after the deposition of grains in the lacustrine environment.     

Monitoring of TDS and conductivity in groundwater in the seismically active region in NW Himalayas,India

<正>The earthquake precursors and earthquake prediction are the burning issue among the community of earth scientists and engineers. Studies of earthquake precursory phenomena since the last several decades have shown that significant geophysical and geochemical changes may occur prior to intermediate and large earthquakes (Hartmann and Levy, 2005; Yang et al, 2005;     

Mycorrhizal Colonization Affects the Survival of Vetiveria zizanioides (L.) Nash Grown in Water Containing As(III)

The presence of arsenic (As) in water is of great public concern. Arsenic exists in three common valence states viz., As(0) metalloid arsenic, As(III) (arsenite) and As(V) (arsenate). Arsenite [As(III)] is the most toxic form among arsenicals which, predominates in anaerobic conditions, generally in flooded soils and in the water with high BOD. Experiments were conducted to investigate the effect of As(III) on the mycorrhization in vetiver (Vetiveria zizanioides (L.) Nash) grass in hydroponics. Studies showed significant alteration in the mycorrhizal colonization in the roots of vetiver exposed to higher concentrations of As(III) starting from 1.0, 2.0, 3.0, 4.0 to 5.0 mg/L prepared in 5% Hoagland nutrient solution without addition of phosphate ions. Considerable reduction in the mycorrhizal intensity (M) was observed in all the treatment sets as compared to the control suggesting a negative impact of the As(III) on the mycorrhizal association. Simultaneously, the study also showed that, As(III) is toxic to the vetiver plants having mycorrhizal association however plants with non‐mycorrhizal (cleansed) roots were found to be able to survive for a longer period exposed to As(III).