Abstract
Remote sensing is a powerful tool, providing a truly synoptic view of surface water quality. Spectral enhancement of satellite images has improved significantly in recent years. In this research, satellite image data were used to detect, monitor and map different pollutants at five study sites along the El-Gamil beach including; El-Debba, El-Manasra, EI-Fardous and El-Gamil inlets and the El-Gamil airport. The images were rectified and analyzed by ERDAS IMAGINE 8.7. Image processing techniques were applied using ENVI 4.2 to analyze the SPOT image data (10 in resolution) for 2006. Image enhancement, principal component analysis (PCA), band ratios and supervised/unsupervised classifications were applied. Water quality degradation, due to high discharge volumes of domestic sewage and the absence of any substantive controls on the release of toxic materials, was monitored. Surface water samples were collected during the winter of 2005 and the summer of 2006. Water contamination was found to be higher in the summer than in the winter. SPOT image data from the summer, therefore, was selected to verify the results of heavy metal analysis. Six metals, at varying concentrations, were detected along the coast: iron (Fe), manganese (Mn), cadmium (Cd), lead (Pb), zinc (Zn) and copper (Cu). The highest concentrations were: Fe (896 mu g/l) at El Debba; Mn (198 mu g/l) at the El-Gamil airport; Cd (2.7 mu g/1) at El Fardous; Pb (56 mu g/l) at El Debba; Zn (300 mu g/l) at the El Gamil airport; Cu (19.3 mu g/l) in El Manasra. Chemical analyses verified the surface water contamination distinguished from the satellite data. El-Gamil airport, El Gamil and El Fardous inlets were the most polluted sites due to intensive discharge of domestic, agricultural and industrial wastes. Different pollutants detected along the El Manasra and El Debba sites are associated with industrial development, and discharge from natural gas companies and electric power generating stations. Satellite imagery data were verified through a field investigation. Significant water pollution was recorded on the eastern side of the coast due to contaminants carried from the Damietta promontory by longshore currents and from other eastern cities by the reverse seasonal currents. Significant water pollution is not unique to this region of the Mediterranean Sea, but is increasingly common at coastal locations throughout the globe. To protect both the marine environment and commercial interests that depend on clean water and beaches (e.g., beach resorts), effective wastewater management practices must be designed, implemented and maintained, along with reasonable development policies. Remote sensing may be an important tool for monitoring the effectiveness of any pollution mitigation strategies.