Flow–duration–frequency Curves In High-flow Conditions: A Strategic Decision-making Tool For Selected Streams In The Constantinois Coastal Basin, Northeastern Algeria
Auteurs : Labed Mounia . Seghir Karima . Beloulou Laroussi .
Résumé
Effective management of surface water resources in the Constantinois Coastal Watershed (northeastern Algeria) is challenged by strong climatic variability and complex geomorphological conditions. This semi-arid Mediterranean basin (11,509 km²) is characterized by highly variable and intermittent flow regimes driven mainly by episodic runoff. Conventional hydrological approaches, such as descriptive statistics and rating curves, are inadequate as they do not simultaneously account for flow duration and frequency. This study develops a frequency-based approach using hydrometric discharge series, whose observation periods vary between stations and extend approximately from 1946/1947 to 2006/2007, to construct Discharge–Duration–Frequency (QdF) curves. Mean discharges calculated over successive durations were associated with their occurrence frequencies, following a framework analogous to Intensity–Duration–Frequency (IDF) curves used in rainfall analysis. Results indicate an average annual runoff of approximately 3,250 hm³. In the Kebir-East wadi, 30-day accumulated runoff volumes are estimated at about 160 and 196 hm³ for return periods of 10 and 20 years, respectively, with uncertainties below 20% based on the Generalized Extreme Value (GEV) distribution. This work offers an original contribution by extending the QdF approach to intermittent Mediterranean hydrosystems, where hydrological variability and data limitations remain critical constraints. By integrating duration and frequency within a unified probabilistic framework and applying GEV-based synthetic data generation, the proposed method enhances the robustness of flow characterization. It provides a transferable and decision-support tool for water resources management, flood risk mitigation, and hydraulic infrastructure design in semi-arid regions facing increasing hydroclimatic variability
Mots clés
Surface Runoff, Frequency Analysis, Discharge-Duration-Frequency Curves (QdF), Constantinois Coastal Basin, Water Resources Management.
