It has been a long time for the navy research centers to do great efforts and concentrate their researches in developing the used methods for measuring the depths, and increasing their efficiency even this developing is to the traditional methods, or to the remote sensing technique. Due to the presence of the river Nile as a navigational route in Egypt passing from its south to its north, the remote sensing technique was used in this research for measuring the depths, by using multi-spectral band satellite image with resolution 1.65m, which covers an area of almost 15.52 Km²of the river Nile (of width=1Km and length=15.52Km) from Esna to nagaa Hamadii, the image was corrected geometrically, and The radiances were corrected from all of the effective errors. The mathematical equations were used to calculate the reflectance values from the corrected radiance values. From the obtained reflectance, the depths were computed, by using suitable mathematical model. The data analysis mainly depends on the physical principle, which stipulates that upon the passage of electromagnetic waves by aqueous media, it weakens the wave because it passed from a media of a certain density to the media has different densities. The deeper areas will have dark color due to the low light reflected compared with the areas with lower depths. We used the depths measured with echo sounder as reference depths. At the end the estimated depth values were compared with the observed values. The average of the differences was about (1.22 m). |
