# A Real-Time Water Level and Discharge Monitoring Station: A Case Study of the Sakarya River
## 2 Materials and Methods
### Discharge Level Monitoring and Discharge Calculation Integration into the Web System  
The river monitoring station installed on the Orencik Bridge over the Sakarya River has been conducting level readings since 13 June 2022. Flow calculations for the Orencik Bridge section are determined using the Manning's n formula based on the readings taken. The Manning formula is a hydraulic formula used to calculate discharge by utilizing the velocity and cross-sectional area of a flow [31]. The first step in accurately measuring river discharge involves creating a bathymetric map of the river. This map illustrates the underwater topography of the river, showing detailed depth distributions across the riverbed (Figure 11). This map provides critical information about the riverbed's depths and shapes, which are essential for understanding water flow and distribution [32]. For determining the cross-section at the Orencik Bridge, both the bathymetric map and the bridge project cross-section were utilized. The bathymetric map depicts the depth and underwater topography of a specific section of the river. Creating a cross-sectional profile involves calculating the wet area and wetted perimeter, which vary with changes in the water level. Real-time monitoring station installed on the Orencik Bridge measures the distance between the bridge deck and the water surface, facilitating the monitoring of water levels. Figure 12 presents a schematic representation showing the sensor's placement on the bridge deck along with a Google Earth image of the bridge where the sensor is installed. This visual representation clearly displays the position of the sensor and its placement on the bridge. The calculation of the water level is performed by subtracting the distance from the bridge deck to the water surface from the total distance between the bridge deck and the riverbed. Figure 11: Topography of the River and RMS (River Monitoring Station) Location. Figure 12: Schematic Representation of Sensor Placement on Orencik Bridge. The discharge calculation is performed using [PERSON]'s formula:  
\[Q=1/n\times R^{2/3}\times J^{1/2}\times A\]  
The formula represents the calculation of discharge \(Q\) (m\({}^{3}\)/s), [PERSON]'s roughness coefficient \(n\) (m\({}^{1/3}\) s\({}^{-1}\)), the cross-sectional area of the flow \(A\) (m\({}^{2}\)), the hydraulic radius \(R\) (m), and the channel slope \(J\) (m/m) [31]. Based on field studies and measurements, [PERSON]'s roughness coefficient (\(n=0.15\)) has been determined. [PERSON]'s roughness coefficient represents the resistance of the channel to flow, which is influenced by factors such as channel geometry and flow conditions. In this study, the roughness coefficient was calculated by incorporating field-measured flow data into [PERSON]'s equation and was validated through a comparison of computed discharge values with real-time data obtained from the upstream hydropower plant. Furthermore, this value aligns with the ranges reported in the hydraulic literature for channels with comparable physical and hydraulic characteristics [33]. As a result of this comprehensive assessment, the roughness coefficient (\(n=0.15\)) has been determined. The channel slope \(J\) was determined as 0.0025 at the sensor point. This value was obtained through detailed bathymetric mapping and land surveys conducted across the study area. The slope was calculated by measuring the elevation change over a certain distance along the channel. The hydraulic radius \(R\) for the bridge section was calculated using the wetted area \(A\) and wetted perimeter \(P\). The wetted area \(A\) was determined by measuring the cross-sectional area of the flow at the bridge section, while the wetted perimeter \(P\) was measured as the length of the channel boundary in contact with the water. The hydraulic radius \(R\) was computed using the formula \(R=A/P\), where \(P\) represents the wetted perimeter. This calculation was used to characterize the flow dynamics within the channel.