Investigating the trends of hydro-meteorological variables and checking its variability are of great importance for water resources management and development in the River Nile basin. The present study aimed to analyze the rainfall variability and trends in the Upper Blue Nile Basin (UBNB) over a period from 1953 to 2014. Variability analysis showed that the basin has been suffering from variable rainfall events causing severe droughts and floods over different years. According to precipitation concentration index calculations, the basin had irregular and strong irregular rainfall distribution over the annual and dry seasons, while the basin had a uniform and moderate rainfall distribution during the rainy season and small rainy season. For the total annual rainfall, Mann–Kendall test indicated that, for the eastern central part of the basin, a significant increasing trend of 12.85 mm/year occurred over the studied period, while, for the southwestern part of the basin, a significant decrease of 17.78 mm/year occurred. For the rainy season, a significant increasing trend over the northeastern and eastern central parts of the basin with the magnitude of 3.330–12.625 mm/year occurred. Trend analysis was applied on the monthly averaged rainfall over the whole basin and revealed that July and August are the most contributors of rainfall to the basin with 23.32% and 22.65%. Changing point assessment revealed that at Lake Tana outlet there is a decreasing of the rainfall of 17.7% after 1977 that matched with the trend analysis results. The data and results contained herein provide updated information about the current situation in the UBNB. The results can be used to predict future precipitation and estimate the uncertainty in future precipitation prediction models.

The improvement and capacity increasing of hydropower stations have brought attention to the intake structures of water-cooling systems, which suction water from alluvial channels. The accumulation of sediment in the vicinity of these intake structures poses significant operational challenges, such as strong vortices, and irregular flow distribution at pump intakes. One effective approach is the implementation of a sediment deflector system using baffle columns as avoided wall (L-Shape profile) with specific dimensions and arrangement to allow water to go through while preventing sediment ingress into the power station intakes. L-Shape profile means double voided walls, one of them parallel to flow direction while the other wall perpendicular to the flow direction in the upstream of the intake structure. The objective of this study is to optimize the performance of the baffle columns of the deflector system in mitigating sedimentation in front of the intake structures. To achieve this, an undistorted physical model with scale 1:50 is utilized to analyze the impact of a defined angle between the two voided walls of the deflector system. Three trials by changing the angle of the double voided walls (L-Shape profile) from 90° to 120°,135°, and 150°. The results of this study indicate that as the inclination angle of the deflector system increased to 150°, it resulted in uniform flow efficiency in the direction of the flow, less accumulative sedimentation ingress the intake.

Designing hydraulic structures requires careful consideration of local scouring downstream. This study investigated the performance of trapezoidal labyrinth weirs in controlling flow and mitigating scour in straight channels through physical model experiments. Sixty configurations were examined, using weir apex angles of 20°, 45°, 60°, and 80°, heights of 30 cm, 35 cm, and 40 cm, and flow rates of 50–200 L/s. A linear weir served as a reference. The results showed that the 60° apex angle consistently outperformed other configurations, reducing scour depth by up to 41% and scour length by up to 50% compared to the linear weir. It also decreased deposition depth by 40% and length by 50%. Lowering weir height from 40 cm to 30 cm led to reductions of 35% in scour depth and 40% in scour length at low discharges. These improvements remained significant even at higher flow rates, with a 29% reduction in scour depth and 25% in scour length at 200 L/s. This study provides evidence-based recommendations for optimizing labyrinth weir designs to define the relationship between hydraulic efficiency and erosion control. It offers valuable insights into weir geometry, flow conditions, and the resulting scour and deposition patterns. These findings contribute to the optimization of labyrinth weir designs to minimize downstream bed configurations. The tests were conducted under limited flow conditions.

In this study, mooring analysis was conducted for different vessel displacements in various locations in Egypt. The analysis focused on simulating extreme weather conditions to assess the suitability of existing codes and standards in limiting maximum forces on bollards. Locations included Damietta harbor, Suez Canal, Safaga port, and Safaga Abu Tartour, with meticulous consideration of environmental criteria. The analysis incorporated factors such as wind, wave, and current under Lowest Astronomical Tide (LAT) and loaded conditions, utilizing the OPTIMOOR software. Mooring arrangements adhered to Oil Companies International Marine Forum (OCIMF, 2008) guidelines. Results, primarily obtained from OPTIMOOR simulations, allowed for a comparative assessment of bollard forces across different cases and standards. Recommendations include a 10%-20% increase in design bollard forces for vessels with displacements under 50,000 tons, with variations for sheltered areas. Notably, a correlation between maximum bollard force and vessel displacement was observed, aligning with international port and harbor standards. Additionally, this study demonstrated the compatibility between measured mooring forces and OPTIMOOR predictions. OPTIMOOR serves as the basis for developing bollard force guidelines across various berth conditions, including Mediterranean harbors, the Suez Canal, and Red Sea berths. This research contributes valuable insights into the design and safety considerations for mooring systems in diverse maritime environments.