Estimation of Peak Discharge in a Poorly Gauged Catchment Based on a Specified Hyetograph Model and Geomorphological Parameters: Case Study for the 23–24 October 2008 Flood, KALAYA Basin, Tangier, Morocco

Abstract

The determination of discharge from stage measurement is an essential procedure in surface hydrology. Due to limited data availability in terms of discharges and rainfalls, a number of non-flood water levels have been used for deriving a rating curve based on an indirect method with specific cross-sections, longitudinal slope of the river, and bed roughness at the KALAYA gage station. In addition, instantaneous rainfall recordings across the Meloussa gage station are available from 23 October 2008 storm event that have been collected in order to develop temporal distribution (hyetograph). Thereby, it provides the necessary input to generate a continuous rainfall-runoff time series, with the derived instantaneous discharge allowed us to calibrate the simulated stage-discharge hydrograph that covers the entire time of the storm event period from 23 to 24 October. An empirical equation was derived in order to provide the peak flow as a function of the given rainfall quantities, its standard deviation, and its standard deviation error. As a result, a very positive correlation between Runoff and Rainfall was observed with values of 0.999. Additional tests were performed to generate a peak discharge of approximately 486 m3/s, using the observed hyetograph and calibrating CN, Lagtime, and Initial abstraction. The results would improve the quality of the model since it allows for a more precise hyetograph to be simulated over a smaller area.

Keywords

• rating curve
• stage-discharge
• specified hyetograph
• KALAYA watershed
• Tangier-Morocco