Mohsen Isari

Culverts are crucial components of surface water drainage systems, often favored for their cost-effectiveness compared to structures like bridges. However, scouring at the upstream and downstream ends can undermine culvert foundations, potentially leading to collapse and significant damage to surrounding structures. Additionally, culvert blockage during flood events alters the flow structure, increasing the risk of failure. This research investigates the scour of culverts in sandy environments and suggests using barrels to minimize it under various flow and obstruction conditions. This study experimentally investigates the reduction scouring process at the downstream culvert with different inlet blockage rates. It spans flow rates from 4.8 to 20 l/s across both box and circular culverts for two different hydrographs created in seven steps for unsteady flow conditions, while steady flow conditions were analyzed at flow rates of 13.8 l/s and 20 l/s were chosen based on peak discharge in two hydrographs, reducing the scouring process by using the 10 to 11 barrels in (50 mm width, 50 mm length, and 150 mm height) at downstream the culvert sorting in different locations in three options. We conducted experimental tests under both steady and unsteady flow conditions for two distinct hydrographs. Ninety-six experiments are carried out. The median grain size (d50 = 1.77 mm) of sediment material was used in this investigation. The findings were compared to the base case for the same shape and level of blockage. Results indicate that barrels notably diminish scour under steady conditions, reducing the maximum depth of scour (dsm), and the formation of scour holes compared to the base case in the same shape and blockage rate. About (Xsm), the position of maximum scour decreased in most cases when applied to the barrels, and the comparison between circular and box data sets reveals that the maximum scour depth values are greater in the circular data sets than in the box data sets. During unsteady flow, barrels effectively in both shapes when used; a barrel’s maximal scour depth location often reduces the maximum depth of scour (dsm), the position of maximum scour depth (Xsm), and scour hole formation when the used culverts are unobstructed or partially obstructed, and the evaluation of scour depth was often greater in circular culverts during the rising limb of the hydrograph compared box shape for all scenarios. However, when we use an inlet blockage, it does not always result in increases in deepest scour depth in both steady and unsteady flow conditions. Nevertheless, there's a risk of overflow, especially in circular culverts with significant blockage in both flow conditions. The study underscores the importance of hydraulic factors in scour mitigation to improve culvert performance. Comparisons between steady and unsteady flows reveal consistent trends in souring process reduction, emphasizing the potential of barrels for effective mitigation.

Due to climate change and facing water scarcity, especially in developing countries, the need for managing this valuable resource is more important than ever. Climate change problems such as extreme weather conditions (heatwaves or severe cold), floods, and waterlogging have been observed annually in areas exposed to floods, causing significant damage. Climate change has also led to an increased water scarcity, making the use and exploitation of groundwater as a valuable option a top priority. The main goal of this research is to optimize water allocation, store rainwater, and reduce flooding. With the increasing population, these problems and challenges become more evident, hence in this research, the concept of a sponge city in flood-prone areas of Sanandaj city has been identified, and the necessary steps and initial studies for implementing this concept have been carried out. Based on this issues, in this research, the topography of the region under study was examined using Digital Elevation Model (DEM), and then, using GIS software, water catchment areas and low-lying areas were identified. Subsequently, the water infiltration rate for the predominant soil in the province's city was calculated for different types of soil using artificial neural network models. The precipitation rate was also modeled, and the Curve Number (CN) was calculated using NDVI maps and land use maps via QGIS software. Subsequently, suitable locations for implementing the sponge city along with their environment and areas were identified using GIS software. In the allocation section, using WEAP software, it was calculated that the unmet demand (shortage) and total water requirement for urban, industrial, agricultural, and drinking water from groundwater from 2021 to 2042 are 17071.13908 and 20739.05353 million cubic meters respectively. In terms of the amount of water coverage (fulfilled demand) in different years, the amount varies for the mentioned sectors.

This research investigates how the presence of alternating steps in stepped spillways situated downstream of embankment dams affects the flow properties. This investigation employs Flow 3D software for conducting simulations and analysis. The research goals were achieved by creating six numerical models. These models included two with regular step patterns (MR) and four with alternating step patterns (MA), each varying in terms of step heights and configurations. Each model measured 1.08 m in depth, 2.54 m in length, two regular and two alternatives have 0.6 m width, other two alternative models with 0.9 m width. (MR1, MA1, MA3) have 28 steps with 3.6 cm height, (MR2, MA2, MA4) have 12 steps with 7.2 cm height and 4 steps with 3.6 cm height. All models have a longitudinal slope (θ) of 26.6°. The models were subjected to different flow rates, spanning from 8.01 ≤ Q ≤ 164.3 m3/h, in order to examine and analyze their flow characteristics. To simulate the turbulent flow, the Renormalized group (RNG) turbulence model is done in the numerical modelling. Outcomes indicate that alternative steps cause more energy dissipation than regular steps, and alternatives with 0.9 m width dissipate more energy than alternatives with 0.6 m. by increasing discharge energy dissipation will decrease. And those models which have 7.2 cm step height dissipate more energy than models with 3.6 cm step height. As a results MA4 is a best energy dissipator. Moreover, regular steps have longer hydraulic jump length than alternative steps. and models with alternative steps with 0.9 m width have smaller hydraulic jump than alternative step models with 0.6 m. by decreasing discharge hydraulic jump will decrease. And by increasing the steps height the hydraulic jump will decrease. As a results smaller stilling basin is required for MA4.

The study investigated the simulation of flow characteristics over an ogee-type spillway surface. The study's primary goal is to simulate and analyze flow characteristics over an ogee-type spillway, commonly used in water engineering for controlling water flow over a dam or weir. The study focuses on how flow rate changes with different conditions, analyzing how the water level changes along the spillway on the other side. Also, investigating how pressure varies across the spillway surface, understanding how the velocity of the water changes along the spillway, and analyzing the shear stress acting on the spillway surface. The study uses the Flow-3D software to perform numerical simulations. The software utilizes an RNG and LES turbulence model to represent turbulent flow conditions. The choice of this model is expected in Computational Fluid Dynamics (CFD) for simulating turbulent flows. The results are compared with observed data from literature as experimental and numerical simulation. Experimental and simulation data by ANSYS software studied by (Kanyabujinja, 2015). Also, the numerical simulation result of turbulence model "𝑘−𝜀" obtained by (KARIM, 2017). Good agreement is reported between the numerical results by using turbulence model (RNG) compared to experimental results. This signifies that the numerical model effectively mirrors the behavior of the physical flow. The results suggest that the pressure distribution is reduced as the discharge increases and vice versa. This indicates a relationship between flow rate and pressure distribution on the spillway and identifies two regions of negative pressure within the flow domain. The first is located at the ogee curve, and the second is observed at the end of the sloping straight line beyond the ogee curve. To address these findings, it was suggested that the slope of the spillway's horizontal surface could be reduced, or the ogee formula changed. Negative pressure zones can have implications for cavitation, a concern in spillway design. The slope of the spillway surface after the ogee crest is noted to influence pressure distribution and potentially prevent cavitation issues. In conclusion, this study offers valuable insights into the flow characteristics of ogee-type spillways. It effectively demonstrates the accuracy of numerical modelling software, specifically Flow-3D, in representing the system's physical behavior. Moreover, it underscores the significance of comprehending the impact of discharge and spillway design on pressure distribution and cavitation risk.

Land subsidence, unlike other destructive phenomena such as floods and earthquakes, occurs slowly over a long period of time. Due to its irreparable damages, including damage to infrastructure, energy transmission lines (gas, water, and electricity), buildings, creation of sinkholes, flooding in coastal areas, and most importantly, destruction of soil and groundwater aquifers, subsidence has become one of the management concerns and issues of the day.Over-exploitation of groundwater aquifers is the most important factor in causing subsidence. Excessive withdrawal of groundwater has led to an increase in the effective stress rate in the aquifer and a change in the compaction of fine-grained sediment particles. Therefore, as a result of these changes in the aquifer, subsidence occurs in a region. In addition, other natural factors such as the thickness of sediments and the transmissivity of the aquifer can directly and indirectly affect the subsidence phenomenon. This research focuses on calculating, evaluating, and modeling the amount of subsidence affected by over-exploitation of groundwater resources, sediment thickness, and aquifer transmissivity using the radar interferometry method and the multilayer perceptron (MLP) Artificial Neural Network in the Dehgolan plain of Kurdistan province, Iran, from March 21, 2022 to September 24, 2023. The subsidence rate calculated using Sentinel-1 images and the radar interferometry technique indicates that the Dehgolan plain is suffering from the destructive phenomenon of subsidence. The maximum calculated subsidence rate using this method is 165 millimeters and the rate of land uplift is 41 mm , and the spatial distribution of subsidence is more pronounced in the western and central regions than in the eastern regions. In addition to this technique, in the Dehgolan plain aquifer of Kurdistan province, using the MLP neural network modeling method in MATLAB software, the amount of subsidence was predicted and modeled using the results obtained from the radar interferometry method and data on groundwater level changes, aquifer transmissivity, and sediment thickness. These values indicate the high ability of the model in simulating and predicting subsidence compared to the values obtained from the radar interferometry method, so that it is able to predict the missing data of subsidence rate due to geometric distortions with good accuracy. Also, in the regression analysis of the modeled data and the values obtained from the radar interferometry method, an average regression coefficient of 0.92 was achieved, which indicates a very good agreement between these results. Finally, it should be noted that the subsidence trend in the Dehgolan plain is increasing and the damages to the Dehgolan plain aquifer are in no way reversible. Only correct decisions for the future should be made, such as raising awareness, imposing strict prohibitions and penalties to reduce unauthorized and excessive exploitation of groundwater resources, and continuous monitoring of subsidence in the region using neural network modeling and remote sensing methods.