Hydrodynamic modeling of outlet stability case study Rosetta promontory in Nile delta

AbstractThe hydrodynamic features of Rosetta promontory are simulated numerically to minimize the outlet siltation problems. Many coastal structures (i.e. revetments, groins) are used to solve the erosion of the shoreline and siltation in the outlet. However, the shoreline along the promontory is still unstable and these structures did not achieve the expected results to reduce the problem where the erosion problem is shifted down drift. In this research three potential solutions were investigated. The first solution is to apply a soft approach in term of re-establishment of natural hydrologic conditions such as providing additional water discharge processes through diverting Burullus drains to the end of the estuary to achieve the nature and stable condition for the promontory. The second proposed solution is to reach the equilibrium cross section of the outlet by dividing the Rosetta outlet into two parts by constructing two 500m separated jetties. The third solution is to control the sedimentation in the outlet by constructing 450m length jetty attached to the eastern bank of the estuary. Numerical Coastal Modeling System (CMS) was used after tuning the model parameters to check the feasibility of the different proposed solutions on the stability of outlet channel. The study shows that an additional discharge of 47m3/s in the first scenario results in a stable outlet cross section suitable for navigation purposes but with limited effect on the erosion problem

Numerical modeling of vadose zone electrical resistivity to evaluate its hydraulic parameters

Abstract Studying and determining the physical properties and hydraulic parameters of vadose zone sediments is an important key to evaluate the infiltration rate into them and assessing the extent to which aquifer sediments benefit from rainwater harvesting in arid and semi-arid areas. Due to the lack of sufficient data on the characteristics of this zone depths, a numerical modeling was used to simulate the electrical resistivity of these sediments by applying the electrical resistivity method, because it is the most affected by the physical properties of dry and wet sediments. This study was applied as a proposal for application in northwestern KSA to calculate the vertical hydraulic conductivity and transmissivity for the vadose zone. This was implemented by assuming a three-layer model using COMSOL Multiphysics model with different electrical resistivity values depending on some in situ electrical resistivity measurements for shallow depths. Hence, the infiltration rate of sediments in this area can be predicted with depth and its effect on aquifer recharge. The focus was on calculating the vertical hydraulic parameters of the most widespread surface sediments with depth and comparing the results of calculating these parameters for some sediments laboratory-wise to ensure their accuracy. Then, their infiltration rate was inferred separately with depth, predicting their ability to aquifer recharge and make the most of rainwater harvesting. Finally, this study can be considered as a preliminary study to determine the expected forward model of electrical resistivity and hydraulic parameters values for the vadose zone sediments with depth along the area and in any other areas, and then apply them accurately in situ to estimate the extent of its usefulness in rainwater harvesting, especially aquifer recharge

Water Quality Observations in the Marine Aquaculture Complex of the Deeba Triangle, Lake Manzala, Egyptian Mediterranean Coast

Coastal aquaculture is faced with extreme variation in water quality. The Deeba Triangle on Lake Manzala is the largest marine coastal aquaculture-producing area on the Egyptian Mediterranean. Samples from 16 ponds were taken during four seasons (2014–2015), to investigate the variation of 12 water quality parameters at that region. We tested the hypothesis that there is no spatial or temporal variation in water quality of the fish ponds. Fish ponds were statistically clustered into three groups (p = 0.0005) coincident with their geographical location. Hypersaline and transparent waters characterized the western ponds; higher dissolved oxygen and higher nutrients characterized the central region. These spatial differences were principally due to variations in salinity and nutrients of the water sources used for irrigation of the ponds and to differences in the aeration management styles. Strong seasonality was seen in water temperature (following air temperature), nutrients, and turbidity (following the seasonal cycles of various water sources from the Lake Manzala and the seasonality of the petrochemical plants effluents close to these ponds). We conclude that municipal effluents significantly affected, spatially and temporally, the quality of the irrigation water used for coastal aquaculture purposes, which consequently might affect fish yield