With the progress of High Aswan Dam "HAD" construction and filling the upstream reservoir, out of an average annual sediment load of 125 million tons, only about 26.3 million tons passed downstream of the Old Aswan Dam "OAD" in year 1968 which was enormously decreased to about 2.0 million tons in year 2000. This led to conclude that, the average annual suspended sediment downstream "HAD" is enormously decreased from 1600 ppm before "HAD" construction to about 50 ppm. So far, several studies anticipated general degradation along the four Nile River reaches and sever local scour downstream the main hydraulic structures. Therefore, the present study aimed to explore the variation of water surface levels with time and location along the second river reach since the construction of "HAD" till year 2010. The daily records of flow discharges and the corresponding water surface levels along the second reach from year 1962 to 2010 were utilized to deduce the matching stage discharge rating curves.
Following a similar study for the first Nile River reach, assessment of the attainable water surface levels for various periods and locations along the second river reach - at passing 200 million m3 / day – revealed that El-Mataana and El – Shanhoria gauge stations were the only sites subjected to water surface level decline and possible degradation after "HAD" construction. The decrease reached its maximum value of 0.225 m and 0.115 m at El-Mataana and El-Shanhoria gauge stations respectively at years 1979 and 1980 then turned over to increase and possible sedimentation at year 1992 for El-Shanhoria gauge station which reached 0.18 m and 0.355 m in years 2000 and 2010 respectively. On the other hand, the downstream part of the study reach from El-Sheikheya to Qena gauge stations did not subject to any decrease in water surface levels since "HAD" construction till year 2010. The monitored increase in water surface levels in year 2010 revealed a maximum value of 0.675, 0.355, 0.575 and 0.460 m at Luxor, El-Shanhoria, El-Sheikheya and Qena gauge stations respectively with respect to the condition before "HAD" construction. Moreover, the attained results for the condition before and after "HAD" construction revealed narrow distinction for the variation in longitudinal water surface slope which ranges between maximum and minimum values of 5.51 cm/km and 4.98 cm/km respectively. Therefore, unlike the concluded results for the first reach, the second one was not subjected to significant or considerable variations in the longitudinal water surface slope after "HAD" construction. Considering the increase in water surface level is due to general sedimentation of 0.516 m as an average value in year 2010, a total deposited material of 49.16 million m3 was worked out along the represented river reach. This led to conclude that the second River Nile reach is being subjected after "HAD" construction to general regular sedimentation and not degradation as expected from several studies.
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