Incorporating transmission losses in flash flood routing in ephemeral streams by using the three-parameter Muskingum met
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ORIGINAL PAPER
Incorporating transmission losses in flash flood routing in ephemeral streams by using the three-parameter Muskingum method A. M. M. Elfeki & H. A. R. Ewea & J. A. Bahrawi & N. S. Al-Amri
Received: 8 March 2014 / Accepted: 11 June 2014 # Saudi Society for Geosciences 2014
Abstract Stream flow in arid and semi-arid regions is usually in a form of flash floods that occur in dry bed ephemeral streams. In this research, the three-parameter Muskingum method has been investigated as a tool for flash flood routing in arid zones using data from Yiba catchment in the Kingdom of Saudi Arabia. The method is general; it takes into account both lateral inflows from side tributaries and also lateral outflow which can represent transmission losses. Applying the methodology for ephemeral streams requires some modifications of the assumptions. The ephemeral stream is considered as a long linear channel with a total movement time of the hydrograph that consists of two parts, the translation time and the redistribution time. The translation time is the travel time of the flood between two stations, while the redistribution time is the lag time that is estimated from the conventional Muskingum method due to the reshaping of the hydrograph. Eight runoff events have been studied for the model parameter estimation phase, while another four events are considered for the verification phase. A spreadsheet model has been developed to implement the methodology and checked with data from the published literature. The method shows very good results; the average RMSE value is 3 m3/s for the hydrographs of the reconstructed events. The correlation coefficients between observed and calculated parameters show relatively high correlation, i.e., 0.99 for the peak discharges, 0.95 for the time lags, and 0.99 for coefficient of transmission losses (the α-parameter). The maximum transmission loss is estimated to be 84 % of the inflow hydrograph form the studied A. M. M. Elfeki (*) : H. A. R. Ewea : J. A. Bahrawi : N. S. Al-Amri Department of Hydrology and Water Resources Management, Faculty of Meteorology, Environment & Arid Land Agriculture, King Abdulaziz University, P.O. Box 80208, Jeddah 21589, Saudi Arabia e-mail: [email protected]
events. A Monte Carlo approach is followed for the verification of the model. It has been found out that the following set of combination of the routing parameter, i.e., a lower limit of d1, an upper limit of d2 and a lower limit of d3 produces satisfactorily good results for the four independent events. Results indicate that the three-parameter Muskingum method exhibits good results in simulating flash flood routing in arid environments. Keywords Ephemeral streams . Transmission losses . Arid and semi-arid zones . Flash floods . Runoff routing . Yiba catchment . Muskingum method . Kingdom of Saudi Arabia
Introduction Runoff in catchments in arid environments is mainly characterized by a high degree of rainfall variability in space and time. Localized high-intensity, short-duration rainfall storm
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