Many regions of the Nile River are subjected to continuous morphological changes such as bank
failure, bed degradation and aggradations, and the formation of new islands. Some of these changes
resulted as a side effect to man made interventions. These morphological changes have a negative impact
on the efficiency of navigation, pump intakes, and the loss of agricultural lands. A serious and harmful
example of such interventions to the river occurred in the Elrayramoun district, where the people
constructed a road to a ferryboat which extended about 400 meters across the River Nile. A detailed
survey for the river bed and banks were conducted at the site in 2005. The survey results were compared
with old maps from 1982, before the intervention. The results indicated that several morphological changes
occurred at the site, where erosion took place at the east bank, and great deposition occurred at the west
bank. Surface water Modeling System (SMS) was used to simulate the study area to predict the expected
changes at flood flow condition. Moreover, the model was also used to test the best alternatives to reduce
the negative impact on the river. The model was calibrated using actual measurements including bed levels
data, water levels, water current velocity measurements and grain size distributions of bed samples.
Location of erosion zones were determined by estimating the zones subjected to velocity larger than
incipient velocity. Three solutions were tested to remove a portion of this road which contradict the river
and affect its characteristics. The three tested portions were removing 25%, 50% and 75% of the road
length. The locations of erosion and sedimentation zones were determined. The study recommended the
best solution to reduce the harmful effects on the Nile River morphology. |
