Materials and method
The methodology approach mentioned in this study consists of four
stages. The first stage is data collection of hydrographic data,
hydrological records, bed material samples, and velocity measurements.
The second stage is model preparation by mesh generation, model
calibration, and verification using boundary conditions. The third stage
is a model application to evaluate the morphological, hydrological
changes, flooded land analysis, the current maximum conveyance capacity
of the Rosetta branch. The fourth stage is the results and analysis of
the three proposed rehabilitation scenarios’ impact on water surface
profile, inundated land, and conveyance capacity as shown in Figure 1.
Study area
The study area covers approximately 155 km in the Rosetta branch of the
Nile River in Egypt. Extending from Delta Barrage at Km 26 heading north
reaching Shabrakhet gauge station at Km 181 downstream Elroda gauge
station. Rosetta branch is considered a meandering channel whose
sinuosity index is 1.5 and average channel width 122 m. The study area
includes five water gauge stations and one control structure in addition
to 5 drains discharging its effluent directly into the branch as shown
in Figure 2.
Data collection
Hydrological data
Daily water level records of five water gauge stations (Elkhatatba, Abo
Elkhawey, Zaywet Elbahr, Kafr Elzayat, and Shabrakhet) and flow
discharge records of Delta Barrage were collected for the study. The
average daily discharge of five drains (Elrahawey, Sabl, Eltahrer,
Zawyet Elbahr, and Tala) was also collected. The collected data have a
return period of 15 years from 2005 to 2020. The collected data revealed
that the maximum flow discharge values are mainly recorded from June to
August, while the minimum values are from November to January. The
maximum recorded discharge was about 90 million m3/day during the year
2007, while the minimum discharge was 5 million.m3/day during the year
2005.
Hydrographic data
The hydrographic data consists of a Hydrographic survey of the study
area bed level with a length of 155 km during the years 2020 and 2003.
The hydrographic survey was carried out by the Nile Research Institute
(NRI) of the National Water Research Center (NWRC) in Egypt.
Bed material samples and velocity
measurements
Four velocities cross-sections were selected for model calibration and
verification. The streamflow velocity was measured in the field. The
first two were at km 37 while the second two were at km 140 from Elroda
gauge. Also, five locations were chosen for bed material sample
extraction at km (57,64,94,120, and 150) respectively from Elroda gauge
where the average D50 was 0.35 mm and soil
classification was fine to medium sand.