Comparative Analysis of Analytical and Empirical Methods for Estimating the Longitudinal Dispersion Coefficient in Open-Channel Flows
Journal Title: Journal of Civil and Hydraulic Engineering - Year 2025, Vol 3, Issue 2
Abstract
The accurate estimation of the longitudinal dispersion coefficient is crucial for predicting solute transport in natural water bodies. In this study, an analytical (integral) method based on first principles is compared with Fischer’s widely used empirical approach, which is implemented in hydraulic modeling software such as the Hydrologic Engineering Center-River Analysis System (HEC-RAS). The primary objective is to evaluate the accuracy, applicability, and limitations of both methods under varying hydraulic conditions. A key advantage of the analytical approach is its ability to estimate the dispersion coefficient using velocity data alone, eliminating the need for high-cost tracer experiments that rely on solute concentration measurements. The determination index suggests an acceptable level of agreement between the two methods; however, the empirical approach systematically overestimates dispersion coefficients. Furthermore, a clear inverse relationship is observed between the slope of the channel and the magnitude of the dispersion coefficient, which is attributed to the increasing influence of shear velocity on the diffusion process. As slope values increase, solute separation time decreases, and concentration gradients become steeper. Conversely, at lower slopes, solute dispersion occurs over a broader time frame, resulting in lower concentration peaks. These findings indicate that while Fischer’s method provides a robust empirical framework, it should be supplemented with field measurements to improve reliability. In contrast, the analytical method offers a more theoretically grounded alternative that may enhance predictive accuracy in solute transport modeling. The implications of these results extend to water quality management, contaminant transport studies, and hydraulic engineering applications, where the selection of an appropriate dispersion estimation method significantly influences predictive outcomes.
Authors and Affiliations
Mohammed J. Mawat
Keywords
Related Articles
- EP ID EP764859
- DOI https://doi.org/10.56578/jche030203
- Views 29
- Downloads 0
Stability Analysis of Steel Columns with Fixed-Free Ends under Axial Compression: Uniform and Non-Uniform Square Hollow Sections
This study investigates the stability of steel columns subjected to axial compression, focusing on square hollow sections (SHS) with both uniform and non-uniform cross-sections. The stability of fixed-free end SHS column...
Impact of Meteorological Factors on Asphalt Pavement Surface Temperatures: A Machine Learning Approach
Recent observations of global warming phenomena have necessitated the evaluation of the service performance of asphalt pavements, which is substantially influenced by surface temperature levels. This study employed twelv...
Risk Assessment of High-grade Highway Construction Based on Combined Weighting and Fuzzy Mathematics
High-grade highways are an important part of the modern comprehensive transportation system. However, due to frequent natural disasters, harsh meteorological conditions, and fragile geological environments, high-grade hi...
Mechanisms of Cracking and Stress Control During the Construction Phase of Concrete Face Rockfill Dams in Cold Regions
The construction phase of concrete face rockfill dams is often marred by prominent panel cracking issues, with a lack of reliable foundations for anti-cracking design. To control tensile stresses and enhance crack resist...
Numerical Simulation of Resistivity Response Characteristics in Seepage Detection of Cutoff Walls Using Cross-Hole Resistivity Tomography
Cutoff walls are an essential method for seepage prevention in dams. During the construction and operation of reservoirs, factors such as construction techniques, variations in groundwater conditions within the dam body,...