The primary objective of this study was to calculate and assess the irrigation water quality index. Furthermore, an effective method for predicting IWQI using artificial neural network (ANN) and multiple linear regression (MLR) models was proposed. The accuracy performance of each model was evaluated at the end of this paper. According to the calculated index based on 49 groundwater samples, the Sidi El Hani aquifer was of good and sufficient quality. Moreover, both the ANN and MLR models performed well in terms of actual and predicted water quality. The ANN model, on the other hand, demonstrated the highest prediction accuracy. The results of this model also revealed that the predicted and computed values were close, with determination coefficients R2, RMSE, and MAE of about 0.95, 1.02, and 0.90, respectively. As a result, the proposed ANN model in this study was consistent and sufficient. These findings will help to guide irrigation water management decisions for the study aquifer in the future. The proposed ANN model can also be used to estimate the irrigation water index of other semi-arid aquifers, but accuracy is dependent on proper training techniques and selection parameters.

Scour tests on downstream roller bucket energy dissipators have shown that, at the equilibrium, bed characteristics are mainly influenced by the discharge and by the height of the bucket lip. The discharge affects scour characteristics, without however modifying the shape of the bed. On the other hand, the height of the bucket lip simultaneously affects scour characteristics and the shape of the bed mainly in the vicinity of the structure. In the latter area, for larger values of the height of the bucket lip, one observes a deposition with a small depression on the top and, on the contrary, when the height of the bucket lip is small, one observes an erosion. Both the depth of scour and the thickness of the deposit increase proportionally to the height of the bucket lip. Values of the other bed characteristics decrease slightly with the height of the bucket lip to reach a minimum, then they increase for higher values of the height of the bucket lip. Comparison of bed characteristics at the equilibrium with the literature shows that theory overestimates the depth of the scour measured in the laboratory by an average of 68% for the three values of discharge, underestimates the impact distance by about 6% for low discharges, and overestimates it by 10% for the highest discharge.Key words: hydraulic energy dissipation, roller bucket, scour mecanism, scour, small-scale model.

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The continuous scour of an erodible bed downstream a roller bucket energy dissipater makes it difficult to quantify the efforts applied on the bed. An astute technique allows the measurement of these efforts for various stages of scour and facilitates a better comprehension of the interaction between these efforts and the scour downstream. This technique consists in measuring the bed profile (downstream the dissipater) as a function of time and reproducing scoured profiles using a solid model (concrete) that allows the setting of the measuring devices. The analysis of the efforts has shown that as soon as the scour starts, a small bed deformation induces important changes in the pressure and in the pressure fluctuation distributions in the vicinity of the structure. As erosion goes on, the efforts vary slightly and the distributions remain unchanged. The behaviour of the efforts regarding the erosive process could be interpreted by the nature of scour phenomenon, which develops strongly during the initial phase, and by the specific behaviour of the zone in the vicinity of the bucket, which evolves rapidly and stabilizes quickly.Key words: hydrodynamic efforts, pressure, pressure fluctuation, energy dissipater, roller bucket, movable bed.