Author Copy • Author Copy • Author Copy • Author Copy • Author Copy • Author Copy • Author Copy • Author Copy • Author Copy Introduction Estimation, quantification, and comprehension of sediment transportation in dynamic systems are important for project planning: estimation of dam silting, degradation of aquatic habits, coastline changes [1], and developing efficient agricultural land management strategies [2-4]. Erosion, soil loss assessment, water treatment, association of pollutants with sedimentary particles, and particle depositions at dam reservoirs are all outcomes of suspended sediment phenomena [1, 5, 6]. Quantities of sediment drained to the outlet are linked to several complex factors, such as catchment characteristics, land occupation, channel morphology, initial soil moisture, and hydrological and climatic conditions [7-9]. Estimation of sediment concentration is commonly performed using sediment rating curves with a power function. These curves represent the average relationship between discharge and suspended sediment concentration within a specific watershed [10-13]. Analyzing the Q-SSC relation graphs during flood events allows for the identification of sediment source patterns, which sometimes show hysteresis [14]. Hysteresis pattern is a graphical tool used to analyze and understand the behavior of sediment concentration Pol. J. Environ. Stud. Vol. 33, No. X (2024), 1-8 DOI: 10.15244/pjoes/185705 ONLINE PUBLICATION DATE: *e-mail: hydraulique.eau@gmail.com Original Research Q-SSC Behavior During Floods in the Isser Watershed, (North-West of Algeria) Djouhra Baloul 1, 2* , Abderrahmane Nekkache Ghenim 1 , Abdesselam Megnounif 1 1 'Eau et Ouvrage dans Leur Environnement' Laboratory, University of Tlemcen, BP 230, 13000 Tlemcen, Alegria 2 Institute of Technology, University of Bouira, 10000 Bouira, Algeria Received: 5 December 2023 Accepted: 5 March 2024 Abstract The study aims to establish a graphical relationship between sediment concentration (C) and water discharge (Q) during flood events in the Isser catchment. Hysteresis, indicating a time lag between discharge flow (Q) and suspended sediment concentration (SSC) curves, varies based on sediment availability, event magnitude, and sequence. Based on the 2026 data pairs of water discharge and suspended sediment concentration (Q-SSC), we have selected 22 flood events. The most frequent hysteresis loops were complex (10 loops), with 08 clockwise loops, 02 figure-eight loops, and 02 anti-clockwise loops. Complex hysteresis loops accounted for 63% of solid loads and 37% of water discharge loads, while 50% of total water yield and 23% of total sediment yield were associated with clockwise loops. Principal Component Analysis (PCA) revealed that water discharge load, mean concentration, maximum concentration, and concentration at the flow discharge peak are key variables influencing hysteresis patterns. Keywords: sediment concentration, discharge, hysteresis, ACP, Wadi Isser