Effect of Physical Parameters on the Transparency of Ichkeul Lake’s Waters, North–East of Tunisia

The construction of dams on the Ichkeul Lake rivers, along with drought, has increased the sedimentation problem and caused the decrease of its storage capacity. Therefore, this work aims to highlight the factors responsible for water clarity deterioration. Through the multi-date MODIS imagery analysis, a Water Turbidity Index (WTI) was used to assess the turbidity of the lake and a Delft3D-FLOW hydrodynamic model was used to determine the effect of wind, water level, temperature, and salinity on the turbidity of the lake’s waters. The effect of prevailing wind was analyzed for the two hydrological years 2014–2015 (R² = 0.3989) and 2015–2016 (R² = 0.4219). It was found that the water transparency decreases with the increase of wind speed. Besides, the model calibration showed the sensitivity of water temperature and salinity to the lake’s bed roughness. Contrariwise, the water level was not significantly influenced. Consequently, the use of roughness n = 0.018 decreases the errors between observed and simulated data. Altogether, the methodology used in this work allows decision makers to monitor the temporary and spatial water turbidity fluctuations in the Ichkeul Lake.