Otmane et al. (2025) Contribution of hydrological modeling to the estimation of groundwater deficit and/or excess in a karstic aquifer: the case of Wadi Sebdou catchment (Tafna, NW, Algeria)

Identification

• Journal: Environmental Monitoring and Assessment
• Year: 2025
• Date: 2025-12-05
• Authors: Abdelkader Otmane, Radia Gherissi, Halima Belarbi, Abdelhakim Belaroui, Walid Rabehi
• DOI: 10.1007/s10661-025-14866-x

Research Groups

• Faculty of Natural Sciences and Life, Karman, Ibn Khaldoun Tiaret University, Tiaret, Algeria
• Laboratory 25: Water and Soil Resources, Science and Technology Faculty, University of Tlemcen, Chetouane, Algeria
• Science and Technology Faculty, University Centre of Maghnia, Maghnia, Tlemcen, Algeria
• Laboratory for Water and Structures in Their Environment (EOLE), University of Tlemcen, Tlemcen, Algeria
• Laboratory of Geo-Environment, Faculty of Earth Sciences, Geography and Territorial Planning, FSTGAT/USTHB, Algiers, Algeria
• Laboratory PLACES, CY CERGY Paris University, Cergy-Pontoise, France

Short Summary

This study aimed to estimate the groundwater deficit and characterize the hydrodynamic behavior and self-renewal capacity of the karstic aquifer in the Wadi Sebdou basin, northwestern Algeria. Using the GARDÉNIA hydrological model, it quantified an average groundwater deficit of 1.36 × 10^6 cubic meters per year, compensated by regional karstic system inputs, and established the aquifer's consistent hydrodynamic response to recharge.

Objective

• To estimate the average groundwater deficit and/or excess in the Wadi Sebdou karstic aquifer during the observation period.
• To characterize the hydrodynamic behavior of the karst aquifer in response to varying levels of natural recharge, thereby assessing its self-renewal capacity.
• To establish a hydrological balance for the basin by quantifying its different components and their temporal variations.

Study Configuration

• Spatial Scale: Wadi Sebdou basin, a tributary catchment within the Tafna River basin in northwestern Algeria, covering an area of 616.8 square kilometers.
• Temporal Scale: Data collected over 41 years (September 1975 to August 2016). Model calibration period: September 1976 to August 2005 (29 years). Model validation period: September 2005 to August 2016 (11 years). Analysis of hydrological processes focused on the calibration period.

Methodology and Data

• Models used: GARDÉNIA (version 8.3), a global conceptual hydrological model with an analogical reservoir framework, simulating water cycle mechanisms using simplified physical laws.
• Data sources:
  • Hydroclimatic dataset (monthly and annual time steps) from the National Meteorological Office (ONM) and the National Agency of Hydraulic Resources (ANRH).
  • Rainfall data from three stations, spatially averaged using the Thiessen polygon method. Missing data interpolated using linear regression.
  • Runoff data from the Bni–Bahdel dam gauging station.
  • Potential evapotranspiration calculated using the Turc formula (1955) with temperature data from Beni–Bahdel station.
  • Land cover map produced from Landsat 8 satellite imagery (30 meter spatial resolution) using supervised classification.

Main Results

• The GARDÉNIA model achieved satisfactory calibration for the period 1976–2005, with simulated flows closely aligning with observed values, despite some underestimations attributed to the basin's karstic nature.
• The hydrological balance for the calibration period (1976–2005) showed an average annual rainfall of 389.5 millimeters (100%), distributed as: 286.8 millimeters evapotranspiration (73.6%), 59.3 millimeters groundwater recharge (15.3%), and 104.9 millimeters runoff (43.4 millimeters surface flow, 61.5 millimeters groundwater flow).
• The aquifer in Wadi Sebdou basin receives an average external groundwater input of 2.2 millimeters per year, resulting in an average deficit of 1.36 × 10^6 cubic meters per year. This deficit is compensated by the regional karstic system of the upper Tafna.
• A balanced water budget (zero external groundwater flow) requires an annual recharge of 61.5 millimeters.
• Under zero recharge conditions, the theoretical maximum groundwater flow contribution from the regional karstic system could reach 37.13 × 10^6 cubic meters per year (60.2 millimeters).
• The continuous flow of Wadi Sebdou is primarily sustained by groundwater flow, with surface flow limited to short-lived responses during extreme seasonal events.
• Recharge is inversely correlated with external exchange flow (correlation coefficient of 0.81), indicating that the aquifer gains water from surroundings during dry periods and exports water during wet periods when recharge is high.
• Model performance decreased during the validation period (2005–2016) due to significant climate variability and extreme events (droughts and floods).

Contributions

• Demonstrated the effectiveness and performance of the GARDÉNIA model for hydrological balance estimation and understanding the hydrodynamic functioning of karstic aquifers in semi-arid regions.
• Provided a quantitative assessment of groundwater deficit and excess in a karstic aquifer, highlighting the critical role of regional karstic systems in aquifer replenishment.
• Characterized the complex hydrodynamic behavior of the karstic aquifer, including its interaction with recharge, external groundwater exchanges, and the influence of evapotranspiration on these processes.
• Confirmed the impact of climate variability and extreme events on hydrological regimes in the study region.

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Citation

@article{Otmane2025Contribution,
  author = {Otmane, Abdelkader and Gherissi, Radia and Belarbi, Halima and Belaroui, Abdelhakim and Rabehi, Walid},
  title = {Contribution of hydrological modeling to the estimation of groundwater deficit and/or excess in a karstic aquifer: the case of Wadi Sebdou catchment (Tafna, NW, Algeria)},
  journal = {Environmental Monitoring and Assessment},
  year = {2025},
  doi = {10.1007/s10661-025-14866-x},
  url = {https://doi.org/10.1007/s10661-025-14866-x}
}

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