الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
This clear water with 50 - 100 ppm has washed away most of fine materials of canals boundaries upon which the roughness values were changed much. This change has affected the hydraulic efficiency of canals in other words affecting the conveying capacity of canals. This
’( phenomena was investigated dnring the preseii:i19 .study where field measurements together with flume experiments were carried out.
Nine canals were selected for field works. The canals have covered all different canals’s degrees in Egypt, starting from Rayahs to large main and main canals. Medium canals have been also taken into consideration. The selected canals were Rayah’s Monoufy, Tawfiky, Behery, and Nassery. The canals are Ismaelia, Sharkawia, Bassusia, Nagael and Ciarawa. These canals covered both large and medium carreir
canals.
I
The range of discharge for the 9 selected canals varried from 2.0 to 280 m3/sec. They have also covered all types of boundary materials starting from, lsmaelia canal, having boundary material of sandy soil.in the east of Delta, passing through silty to sandy soil in middle of Delta represented by Rayah ’s, Tawfiky, Monoufy, and Sharkawia, Bassusia, Darawa, Nagael canals, to again sandy soil for Rayahs Behery and Nassery.
The selected canals were also free of aquatic weeds and do not need any types of maintenance exccept the maintenance of the water structures. Velocity and discharge measurements were carried out on the...