Floods are the most common natural disasters on earth. Population growth with global warming and climate changes increases the impact of floods on people every year. Combating natural disasters such as floods is possible with effective disaster management. An effective disaster management can only be possible with a comprehensive risk analysis. Flood risks depend on many factors such as precipitation, flow, earth slope, soil structure, and population density. A holistic flood risk analysis considering all these factors will provide a more effective disaster management. This study focuses on an assessment of flood hazard analysis in Bitlis province of Turkey using analytical hierarchy method which is a multi-parameter modeling technique. Flood hazard zones were mapped according to the weight of the selected factor by using geographic information system. It is concluded that while especially the south-western regions are exposed to high flood risk due to high stream density and precipitation, the high slope and rugged nature of this region restrict the risk mainly to the vicinity of low elevation streams and high population regions.

Labyrinth weirs present an effective solution for high discharge efficiency in space-restrictive situations. However, these weirs exhibit negative effects (vibrations, noise, and instability) when the nappe clings to the downstream surface of the weir because of subatmospheric pressures. Nappe breakers are used to limit the occurrence of this behavior. Currently, only a limited number of investigations have focused on the performance of nappe breakers when applied to circular labyrinth weirs. The present study has been designed to provide detailed performance data for sharp-crested circular labyrinth weirs for the case of a simple weir as well an augmented weir (with nappe breaker). Three-dimensional (3D) computational fluid dynamics (CFD) models were verified by comparison with the experimental observations, and then the pressures under the jet flow at the downstream of the weir were scrutinized using a two-phase (water-air) turbulent numerical model. The results of both the numerical simulations and experimental observations confirm the positive outcomes obtained through the use of the nappe breakers to control subatmospheric pressures on the downstream face of the weir.

The Marmara Region (NW Turkey) has experienced significant earthquakes (M > 7.0) to date. A destructive earthquake is also expected in the region. To determine the effect of the specific design spectrum, eleven provinces located in the region were chosen according to the Turkey Earthquake Building Code updated in 2019. Additionally, the differences between the previous and updated regulations of the country were investigated. Peak Ground Acceleration (PGA) and Peak Ground Velocity (PGV) were obtained for each province by using earthquake ground motion levels with 2%, 10%, 50%, and 68% probability of exceedance in 50-year periods. The PGA values in the region range from 0.16 to 0.7 g for earthquakes with a return period of 475 years. For each province, a sample of a reinforced-concrete building having two different numbers of stories with the same ground and structural characteristics was chosen. Static adaptive pushover analyses were performed for the sample reinforced-concrete building using each province’s design spectrum. The variations in the earthquake and structural parameters were investigated according to different geographical locations. It was determined that the site-specific design spectrum significantly influences target displacements for performance-based assessments of buildings due to seismicity characteristics of the studied geographic location.

The bottom-inlet aerator can efficiently protect a spillway chute surface from cavitation damage due to high-flow velocities. This aerator, unlike conventional ones, is especially preferred at low Froude numbers and with wide spillway chutes to overcome submerged aerator conditions. In this study, the aeration performance of bottom-inlet aerators was investigated for different Froude numbers and ramp heights. Some practical formulas based on experimental and numerical data were obtained to estimate the air entrainment coefficient (and thus the average air concentration) of the bottom-inlet aerators. The findings were compared to some empirical results in published literature for conventional aerators, and then discussed.

Due to high flow velocity, the spillway surfaces of high-head dams can expose to cavitational damage. The most effective and economical method of protection from this damage is aerated to flow using aerators. In this study, a spillway aerator of the roller-compacted concrete dam of 100 m height was analyzed using two-phase computational fluid dynamic model to overcome the cavitation damage on the spillway surface. The numerical analysis with prototype dimensions was performed for various flow conditions (5223, 3500, 1750 and 1000 m³/s of flow rate), and obtained results were compared with some experimental observation in the literature. Numerical and experimental results indicated that the cavitation occurs on the surface after a certain downstream point based on cavitation indices. The air entrainment rate and air concentrations supplied by means of the aerator were determined to avoid the cavitational damage. While the experimental results can contain considerable scale effect in terms of air entrainment rate owing to, e.g., viscous effects especially for small scales, the numerical models with prototype dimensions gave much more accurate results. In other words, it can be also mentioned that the actual aeration amount is much greater than that obtained from the model experiments. The results based on numerical analysis showed that the aerator device meet air demand to prevent the cavitation damage.