الفهرس 
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Abstract
The present study use Landsat-7 satellite and Aster data combined with surface measurements for mapping water quality parameters of Manzala lagoon. ETM+ bands 1,2,3,4,5,7,8 ignores thermal bands were compared with in situ measurements and laboratory analysis of water samples. The ETM+ major improvement over the TM was the addition of an eighth, panchromatic band operating in the 0.50-to 0.90 µm ranges with a spatial resolution of 15m Change in the design of the detector system for the ETM+ were to also permit the data for all bands to be automatically co registered, as they were required. For image processing procedure and the evaluation of result ERDAS Imagine 9.1 software was used. Layer stack model was used to display the whole bands of the image. After that, atmospheric corrections are applied to remove the influences of extrinsic sensor, atmospheric influence on water leaving light signal. Atmospheric correction for each band generic from raw Landsat- 7 digital number (DNs) by using 6S Model but Terra-Aster was geometrically and atmospherically corrected by image provider (https: //wist.echo.nasa.gov). The water quality parameters are correlated with the atmospheric corrected data. A 3×3 window was established around each sampling pixel to maximize the accuracy of data collections. The mean reflectance of the 3×3window was extracted and used in the modeling process. The relationship established between the surface measurements and Landsat-7 and Aster data reflectance data were extended to the entire study area and to the immediate surrounding, producing a series of class maps which were grouped and color-coded to represent the distribution of water quality parameters. Based on the results from visual interpretation of processed Landsat-7 (ETM+) and Terra-Aster images 2007 the best results maps was generated showing the distribution of bathymetry, chlorophyll-a, NO-2, TP, TDIP and turbidity. Firstly, by comparing the first Chlorophyll-a map derived by ETM+ data by the Chlorophyll-a map derived from Aster data, it is noticed that over time and increasing encroachment on the body of lagoon Chlorophyll-a concentration increased. Also there is spatial dispersion of broad Chlorophyll-a in most parts of the lagoon as shown on (Plate 2 and 5). This phenomenon may be due to the rapid spread of water hyacinth, which is characterized by its ability to spread rapidly with the movement of water. This was noticed during field survey. Anglers bring water hyacinth to the lagoon then raised and installed it on the veins of wood in a circle and then placed in the center of that body of some dead animals, which attract fish inside the flat where they are after twenty days fishing these fish and this approach leads to the deposition of such large amounts of water hyacinth in the bottom of the lagoon with time and the lagoon dry up. On the other hand comparing the turbidity map derived from Landsat-7 image data by the second turbidity map derived from Terra-Aster. It is noticed that turbidity also increased with passage of time especially in the northern and southern part of lagoon which may be due to the increased of fish cages. For Total Phosphorous and Nitrite distributed in different concentration in all parts of the lagoon, but high concentrations of it were found in northern and southern regions, which may be due to the spread of small basin which is called (Hoshas).