A Combination between Synthetic Unit Hydrograph (SCS) and Rational Method in a similar Conditions Water Shed


  • Mona Fathi Benha University, Egypt
  • Neveen B. Abelmageed Civil Engineering Department, Faculty of Engineering at Shoubra, University, Egypt
  • M. Hassan Civil Engineering Department, Faculty of Engineering at Shoubra, University, Egypt




Wadi Dahab, HEC-WMS software, DEM, IDF curves, hyfran-plus software


Studying watershed characteristics and choosing the most applicable methods to determine the amount of access rainfall that ran off is very important in many engineering applications, especially hydrology applications. That is to know the more suitable methods for protection against floods and to maximize benefits from the excess water. This study aims to establish a relation between the rational method and the SCS method. A subbasin in Wadi Dahab in Sinai, Egypt is investigated as a study area. To achieve the study aims, HEC-WMS software is chosen, which can analyze a watershed by using DEM and delineating basin. It calculates also important watershed parameters like area, runoff distances, and slope. The rainfall data is compiled and arranged. A statical analysis is executed to obtain the IDF curves. Hyfran-plus software is employed to locate the maximum depths for different return periods. Various values for the time of concentration are studied.

It is concluded that the difference between the rational and SCS methods is great for the time of concentration till 2 hours, then it decreases obviously from 2 till 6 hours. Also, it is concluded that the difference between the two methods is bigger for the small return periods of 2 and 5 years for all values of the time of concentration.

Employing the obtained equations, the peak runoff for one of the two methods (the rational and SCS methods) can be calculated knowing the time of concentration and the peak runoff for the second method.



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How to Cite

Fathi, M., Abelmageed, N. B. ., & Hassan, M. (2021). A Combination between Synthetic Unit Hydrograph (SCS) and Rational Method in a similar Conditions Water Shed. Asian Journal of Engineering and Technology, 9(3). https://doi.org/10.24203/ajet.v9i3.6622