A convection decay model for simulating the transmission of flood waves in ephemeral channels in arid zones

05/02/2023

A CONVECTION-DECAY MODEL FOR SIMULATING THE TRANSMISSION OF

FLOOD WAVES IN EPHEMERAL CHANNELS IN ARID ZONES

Dept. of Hydrology and Water Resources Management ,Faculty of Meteorology, Environment & Arid Land Agriculture, King Abdulaziz

University , P.O. Box 80208 Jeddah 21589 Saudi Arabia* Faculty of Engineering Mansoura Universirty

Amro M.M. Elfeki, Hatem A. Ewea, Jarbou A. Bahrawi and Nassir S. Al-Amri(ICWRAE 2014)

Authors: Amro M.M. Elfeki*, Hatem A. Ewea, Jarbou A. Bahrawi and Nassir S. Al-Amri

Presenter: Mohammed Farran

05/02/2023

Outline Problem Statement. Research Objective. Study Area. Field Observations and Measurements. Conceptual Model. Model Development and Parameter

Estimation Results Conclusions

Amro M.M. Elfeki, Hatem A. Ewea, Jarbou A. Bahrawi and Nassir S. Al-Amri (ICWRAE 2014)

05/02/2023

Problem Statement

o In the literature, researchers usually use three parameter Muskingum method for river flood routing with lateral inflow (O'Donnell, T. (1985).

o Recently the method has been applied on ephemeral channels to incorporate transmission losses with success by Elfeki, et al. (2014).

o The Muskingum method relies on three parameters. The fitting procedure of these parameters can led to unphysical values.


05/02/2023

Research ObjectiveDevelopment of a convection-decay model for simulating the transmission of flood waves in ephemeral channels.

The model has two merits:1. Depends on two parameters not three like in

Muskingum method. 2. The parameters have physical interpretation.


05/02/2023

Study Area


- Yiba basin is located in Makkah Al-Mukaramah region, in the southwestern part of Saudi Arabia.

- It has an area of 2346 km2 and drains its water towards the Red Sea.

05/02/2023

Field Observations and Measurements


05/02/2023

Catchments and Channel Characteristics


Station Area (km2)

Length of the main stream (km)

Basin Slope (m/m)

Channel reach length (km)

422 306.01 23.3 0.332210.5

401 764.96 35.07 0.2833

423 612.83 36.2 0.265732.2

424 2346.27 51.8 0.1969

05/02/2023

v is the flood wave velocity,Q is the discharge hydrograph,α is the decay coefficient, andx and t are the space and time variables

Conceptual Model of Flood Wave Transmission


05/02/2023

Parameter Estimation


05/02/2023

Model Development


05/02/2023

Summary of Parameter Estimation


05/02/2023

Model Results (Station 422-401)


05/02/2023

Model Results (Station 423-424)


05/02/2023

ConclusionsBased on the proposed model, The average flood wave speed:Reach 422-401 is 10 km/hr Reach 423-424 is 7.4 km/hr

The average decay factor:Reach 422-401 is 0.78 hr-1

Reach 423-424 is 0.26 hr-1

Both reaches show good agreement in terms of flood attenuation, while for reach 423-424 there is an early arrival of the flood wave that need further investigation. The model in some sense is capable of simulating flood wave movement in ephemeral streams.
