Evaluation of the predictive performance of general scour equations along the Nile River

E Helal, H El Sersawy, M Abdelbaky - ISH Journal of Hydraulic …, 2022 - Taylor & Francis
E Helal, H El Sersawy, M Abdelbaky
ISH Journal of Hydraulic Engineering, 2022Taylor & Francis
ABSTRACT The Nile River is considered one of the most important rivers in the world. The
scouring of such a river must be comprehensively studied. Therefore, studying the general
scour of the Nile River and adjusting the relevant scour equations are very important. Field
data were collected (bathymetric, hydrological, and hydraulic) for several years in the
selected study area (a river reach with a total length of 54 km). A geographic information
system (GIS) database application was established to determine the scour hole …
Abstract
The Nile River is considered one of the most important rivers in the world. The scouring of such a river must be comprehensively studied. Therefore, studying the general scour of the Nile River and adjusting the relevant scour equations are very important. Field data were collected (bathymetric, hydrological, and hydraulic) for several years in the selected study area (a river reach with a total length of 54 km). A geographic information system (GIS) database application was established to determine the scour hole characteristics. The scour equilibrium state (active, stable or passive) was classified according to the field observations. A numerical model was developed to calculate the hydraulic characteristics of the Nile River. Seven equations were selected to evaluate the general scour depth. The predictive performances of these equations were assessed using field data and computed scour depths. Four statistical tests were performed to evaluate the performances of the scour equations. The results showed that the equations are inadequate and can potentially lead to underestimation of the scour depth. The Lacey Natural Resources Conservation Service (NRCS) equation performs better than the other equations considered. The selected equations were modified to improve the prediction of the general scour depth of the Nile River. A new general scour equation was derived to simulate the Nile River general scour. Compared to the previously discussed equations, this new equation provided the most accurate prediction of general scour in the Nile River.
Abbreviations: The following abbreviations are used in this paper. AHD = Aswan High Dam; ASCII = American Standard Code for Information Interchange; CAD = Computer-aided design; FESWMS = Finite Element Surface Water Modelling System; GIS = Geographic information systems; MAD = Mean absolute deviation; MAE = Mean absolute error; MKS = Metre-kilogram-second; NRCS = National Resources Conservation Service; NRI = Nile Research Institute; R2 = Coefficient of determination; RMSE = Root mean square error; SMS = Surface Water Modelling System; SPSS = Statistical Package for the Social Sciences; USBR = United States Bureau of Reclamation; UTM = Universal Transverse Mercator; WGS84 = World Geodetic System; 2D = Two-dimensional
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