Publications internationales
Résumé: The intensification of extreme rainfall events driven by climate change presents a critical challenge to urban drainage systems, significantly elevating flood risks. This study assesses the vulnerability of Algiers' urban drainage network by integrating climate projections with hydrological-hydraulic modeling. High-resolution precipitation projections from the MRI-AGCM3.2S global climate model were downscaled to construct Intensity-Duration-Frequency (IDF) curves for a historical baseline (1986–2005) and two future horizons (2046–2065 and 2081–2100) under the RCP 8.5 scenario. These projections data were incorporated into the MIKE URBAN model, which was calibrated and validated for the Algiers basin, to simulate the network's response under different climate scenarios and to identify flood-prone areas. Results show, for a ten-year return period, a substantial increase in both rainfall intensity and the number of flood-prone locations within the drainage system. The number of critical overflow points increases from 323 historically to 602 by the end of the century, representing an 86.4% rise, indicating a profound loss of hydraulic capacity. Furthermore, future 10-year storms in 2100 generate 27.27% more overflow points than historical 100-year storms, illustrating a marked degradation in network resilience and a shift towards more extreme effective storm severity. The study further introduces a structured decisionsupport framework for prioritizing interventions and informing adaptive planning. These findings underscore the urgent need for climate-resilient urban infrastructure strategies to mitigate the growing flood risks in Algiers and similar Mediterranean coastal cities.
Résumé: The Madjez Ressoul watershed, located in Algeria (A = 103 km2), provides a unique opportunity to investigate the accurate prediction of flood hydrographs in a natural setting and relatively untouched environment. Its particularity is an excellent option for simplified rainfall–runoff models due to the potential reduction in model complexity and data requirements. This study applies the Hydrologic Engineering Center’s Hydrologic Modeling System model to simulate 36 year rainfall–runoff modeling (1973–2009). The originality of this study lies in employing experimental infiltration data to improve rainfall–runoff prediction. The study offers valuable insights into the hydrological behavior of the Madjez Ressoul watershed by integrating advanced methods and tools when analyzing hydrological responses. Effective calibration refines the model’s ability to predict flow dynamics by adjusting various parameters. Various methods were selected to simulate hydrological processes, including the soil conservation service-curve Number, SCS unit hydrograph, Muskingum, recession baseflow, and channel loss. The model was tested on many continuous events, and the results revealed a good fit between the simulated and observed discharge data. This evaluation was performed using four criteria (the Nash Sutcliff test, root mean square error, percent bias, and correlation coefficient), indicating reasonable accuracy of the model correlation. Using the findings of this study can aid in providing a better knowledge of water flow dynamics in the Madjez Ressoul watershed by opening up new possibilities to inform the development of flood risk management techniques that have the potential to mitigate the adverse effects of floods on the environment.
Résumé: Evaluation and modeling of soil water infiltration are essential to all aspects of water resources management and the design of hydraulic structures. Nonetheless, research focused on experimental studies of infiltration rates in arid and semi-arid regions under unknown boundary conditions remains minimal. This paper investigates the characteristics of the spatial variability of infiltration over a semi-arid rural basin of Algeria. The experiments were conducted using a portable double-ring infiltrometer filled at an equal volume of approximately 100 L of water for each of the 25 catchment locations. Soil moisture contents at the proximity of each test location were evaluated in the laboratory as per the standard NF P94–050 protocol. The experimental results are used to produce the catchment infiltration curves using three statistically fitted infiltration models, namely Horton, Kostiakov, and Philip models. The reliability of the models was assessed using four performance criteria. The statistical regressions of the fitted models suggest that the Horton model is the most suitable to assess the infiltration rate over the catchment with mean coefficients of Nash = 0.963, CC = 0.985, RMSE = 1.839 (cm/h), and Bias = 0.241. The superiority of the Horton model suggests that the initial and final infiltration rates, primarily affected by soil type, initial soil moistures, and land cover, are important predictors of the modeling process over the Madjez Ressoul catchment. The results also infer that the applicability of other models to the different types of undeveloped soils in the study area requires advanced field investigations. This finding will support the understanding of the hydrologic processes over semi-arid basins, especially in advising crop irrigation schemes and methods and managing the recurring flood and drought over the country. Keywords: Philip; Horton and Kostiakov infiltration models; saturated hydraulic conductivity; soil moisture; portable double-ring infiltrometer; Madjez Ressoul catchment; statistical criteria