The assessment of scour depth downstream of weirs holds paramount importance in ensuring the structural stability of these hydraulic structures. This study presents groundbreaking experimental investigations highlighting the innovative use of baffles to enhance energy dissipation and mitigate scour in the downstream beds of rectangular piano key weirs (RPKWs) and trapezoidal piano key weirs (TPKWs). By leveraging three state-of-the-art supervised machine learning algorithms—multi-layer perceptron (MLP), extreme gradient boosting (XGBoost), and support vector regression (SVR)—to estimate scour hole parameters, this research showcases significant advancements in predictive modeling for scour analysis. Experimental results reveal that the incorporation of baffles leads to a remarkable 18–22% increase in energy dissipation and an 11–14% reduction in scour depth for both RPKWs and TPKWs. Specifically, introducing baffles in RPKWs resulted in a noteworthy 26.7% reduction in scour hole area and a 30.3% decrease in scour volume compared to RPKWs without baffles. Moreover, novel empirical equations were developed to estimate scour parameters, achieving impressive performance metrics with an average R² = 0.951, RMSE = 0.145, and MRPE = 4.429%. The MLP models demonstrate superior performance in predicting maximum scour depth across all scenarios with an average R² = 0.988, RMSE = 0.035, and MRPE = 1.036%. However, the predictive capabilities varied when estimating weir toe scour depth under diverse circumstances, with the XGBoost model proving more accurate in scenarios involving baffled TPKWs with R² = 0.965, RMSE = 0.048, and MRPE = 2.798% than the MLP and SVR models. This research underscores the significant role of baffles in minimizing scouring effects in TPKWs compared to RPKWs, showcasing the potential for improved design and efficiency in water-management systems.

The seawater intrusion (SWI) into rivers can lead to many negative consequences, especially on agricultural activities and live ecosystems in upstream areas of rivers. One solution to prevent SWI is using air bubble curtains (ABCs). The objective of this study is to investigate the optimal location of ABCs and airflows. To this end, several tests with different flow and salinity rates were performed and effect of ABC location on SWI investigated. The results show that, when the ratio of seawater to freshwater densities increased from 1.006 to 1.010, the ratio of saline wedge tip velocity to seawater velocity, airflow to seawater discharge ratio for first and second ABCs are raised 60, 58, and 70%, respectively. Also, when the Froude number (Fr) > 0.031, seawater density changes do not significantly affect the process of SWI. Besides, results of the study show that the closer the ABC is to the river downstream, the higher the airflow rates required. In addition, the optimal value of air bubbles for controlling SWI depends on the density of seawater, where more airflow is required to control denser flows. Finally, the regression equations to predict the SWI parameters based on flow properties were derived.

This paper presents an innovative approach integrating the Image Processing Method and the Beer-Lambert Law to study Sea Water Intrusion in riverine systems. Using an experimental setup, this study characterizes the dynamics between saline and fresh waters, providing detailed spatial and temporal salinity distribution analyses. The Beer-Lambert Law using Python is employed to convert image pixel data to accurate concentration measurements, essential for understanding the diffusion and mixing processes of saline wedges. Results showed that the concentration of the salt water is decreased when it flows upstream horizontally. also, the concentration of the saline water is decreased vertically, due to the salt and fresh water mixing. The "Max Concentration Profile" graph shows a sharp peak at the start, reaching approximately 1000 g/cm³, marking the point of saline introduction. Within the first 10 cm, the concentration rapidly decreases to about 600 g/cm³, indicating swift diffusion and dilution. Beyond this point, the concentration gradually decreases, stabilizing around 200 g/cm³ past the 100 cm mark, reflecting ongoing diffusion and mixing processes. The "Concentration Contour" graph shows high salinity concentrations near the bottom 10 cm of the flume. Salinity concentration decreases moving vertically up the flume, indicated by cooler colors. From approximately 30 cm in height, salinity remains low and uniform, suggesting that denser saline water settles at the bottom due to gravity.

This paper presents an innovative approach integrating the Image Processing Method and the Beer-Lambert Law to study Sea Water Intrusion in riverine systems. Using an experimental setup, this study characterizes the dynamics between saline and fresh waters, providing detailed spatial and temporal salinity distribution analyses. The Beer-Lambert Law is employed to convert image pixel data to accurate concentration measurements, essential for understanding the diffusion and mixing processes of saline wedges. This study not only bridges technological advances with hydrological research but also provides crucial data for water resource management in coastal areas affected by Sea Water Intrusion. The integration of the Image Processing Method and Beer-Lambert Law exemplifies a significant advancement in environmental monitoring, promoting sustainable water resource management in regions vulnerable to saline intrusion. Results showed that the concentration of the salt water is decreased when it flows upstream horizontally. also, the concentration of the saline water is decreased vertically, due to the salt and fresh water mixing.

The seawater intrusion (SWI) into rivers can lead to many negative consequences, especially on agricultural activities and live ecosystems in upstream areas of rivers. One solution to prevent SWI is using air bubble curtains (ABCs). The objective of this study is to investigate the optimal location of ABCs and airflows. To this end, several tests with different flow and salinity rates were performed and effect of ABC location on SWI investigated. The results show that, when the ratio of seawater to freshwater densities increased from 1.006 to 1.010, the ratio of saline wedge tip velocity to seawater velocity, airflow to seawater discharge ratio for first and second ABCs are raised 60, 58, and 70%, respectively. Also, when the Froude number (Fr) > 0.031, seawater density changes do not significantly affect the process of SWI. Besides, results of the study show that the closer the ABC is to the river downstream, the higher the airflow rates required. In addition, the optimal value of air bubbles for controlling SWI depends on the density of seawater, where more airflow is required to control denser flows. Finally, the regression equations to predict the SWI parameters based on flow properties were derived.