Assessment of distortion in watermarked geospatial vector data using different wavelets

With the rapid growth of the Internet, the copyright protection problem occurs frequently, and unauthorized copying and distributing of geospatial data threaten the investments of data producers. Digital watermarking is a possible solution to solve this issue. However, watermarking causes modifications in the original data resulting in distortion and affects accuracy, which is very important to geospatial vector data. This article provides distortion assessment of watermarked geospatial data using wavelet-based invisible watermarking. Eight wavelets at different wavelet decomposition levels are used for accuracy evaluation with the help of error measures such as maximum error and mean square error. Normalized correlation is used as a similarity index between original and extracted watermark. It is observed that the increase in the strength of embedding increases visual degradation. Haar wavelet outperforms the other wavelets, and the third wavelet decomposition level is proved to be optimal level for watermarking.     

Fluoride hazard and assessment of groundwater quality in the semi-arid Upper Panda River basin,Sonbhadra district,Uttar Pradesh,India

Abstract

Around 9000 inhabitants in the Panda River basin, Sonbhadhra District, Uttar Pradesh, India, are vulnerable to a “silent” dental and skeletal fluorosis from groundwater consumption. The fluoride source and seasonal groundwater quality variation were studied by collecting 65 groundwater samples in the Upper Panda River basin. Major rock types are phyllites and granite gneissic rocks. Fluoride concentrations are in the range 0.4–5.6 mg/L in the pre-monsoon season and 0.1–6.7 mg/L in the post-monsoon season. Fluor-apatite and biotite mica in the granite gneissic rock were identified as the main provenance of fluoride in the groundwater through water–rock interactions. Due to precipitation of calcium, soils become alkaline with high contents of sodium; these conditions allow fluoride to accumulate in water. According to risk index calculations, the fluoride-affected villages were shown to fall in the fluoride risk zone (with a risk index of around 1.7). On the basis of mineral stability diagrams, groundwater from the weathered and fractured aquifers appears to be stable within the kaolinite field, suggesting weathering of silicate minerals. The groundwater is chemically potable and suitable for domestic and agricultural purposes, except for a few wells in the southern region that are contaminated with high amounts of fluoride.

Editor D. Koutsoyiannis

Citation Raju, N.J., Dey, S., Gossel, W., and Wycisk, P., 2012. Fluoride hazard and assessment of groundwater quality in the semi-arid Upper Panda River basin, Sonbhadra District, Uttar Pradesh, India. Hydrological Sciences Journal, 57 (7), 1433–1452.