Development of Suspended Sediment Rating Curve Model by Statistical Classification of River Discharge Data (Case Study: Ghareh-Sou Coastal Watershed)

• Published in: Iranian journal of science and technology. Transactions of civil engineering 2024, Vol.48 (6), p.4663-4672
• Main Authors: Salarijazi, Meysam, Modabber-Azizi, Sajjad, Mohammadi, Mehdi, Mohammadrezapour, Omolbani, Ghorbani, Khalil
• Format: Article
• Language: English
• Subjects: Accuracy; Cement industry; Ceramics industry; Civil Engineering; Classification; Classification (sedimentation); Coastal zone; Coefficient of variation; Criteria; Engineering; Hydrometric stations; Median (statistics); Research Paper; River discharge; River flow; Rivers; Sediment load; Sediments; Seismic engineering; Statistical models; Suspended load; Suspended sediments; Sustainable development; Water discharge; Watersheds
• ISSN: 2228-6160; 2364-1843
• DOI: 10.1007/s40996-024-01369-x

The suspended sediment rating curve model is widely used to estimate river suspended sediment load in the coastal area. In this study, an attempt was made to develop a suspended sediment curve model using simple methods, and to evaluate the developed models, the Nash–Sutcliffe criterion was used along with the graphical criterion. The recorded data from 10 hydrometric stations in the Ghareh-Sou coastal watershed, located in northern Iran, were used to investigate the developed models. Based on the average (A) and median (M), the river discharge data were divided into four categories: A1, A2, A3, A4 and M1, M2, M3, M4, and different models were divided into two parts (A1A2–A3A4 and M1M2–M3M4), three parts (A1–A2A3–A4 and M1–M2M3–M4) and four parts (A1–A2–A3–A4 and M1–M2–M3–M4) were created. The average Nash–Sutcliffe criterion in the conventional model of suspended sediment rating curve was equal to 0.19 which in the models A1A2–A3A4, A1–A2A3–A4, and A1–A2–A3–A4, respectively (0.58, 0.66 and 0.66) and in models M1M2–M3M4, M1–M2M3–M4, and M1–M2–M3–M4, respectively (0.47, 0.60 and 0.60). Considering the Nash–Sutcliffe criterion values in different models, it can be concluded that classification has had a significant effect on improving the accuracy of the suspended sediment rating curve model. The results show that in the classification with average and median, the accuracy of modeling in the number of classes 3 and 4 is the same, and therefore the optimal number of classes is equal to 3. In addition, classification based on average relative to median has led to a more accurate estimation of suspended sediment load. Also, the study of the coefficient of variation of the Nash–Sutcliffe criterion in different models shows that the classification of data based on the average and median has reduced the variability of the estimate of suspended sediment load, which increases the reliability of the developed models. The graphical criterion also confirms that the developed models have improved the estimate of suspended sediment.