Erosion–Filtration Analysis for Assessing Hydraulic Instability of Dams in Morocco and Global Warming Effect

Abstract

The climate change including very long dry seasons can threaten vulnerability of dams and dikes by reducing their resistance to internal erosion. It is, therefore, questionable how long degradation of soil properties can affect the operating life of hydraulic structures. This research is devoted to investigate the susceptibility to internal erosion of many earth dams in Morocco. For this purpose, many erosion–filtration tests have been conducted on samples collected from core soil or downstream filter of three dams (embankment dam and zoned earth dams). Materials have been analyzed with respect to the particle size distribution, plasticity index, permeability, and their suitability for dam construction. This has been deduced from usual engineering guidelines. The investigation involves combined Hole Erosion–Filtration experiments for modeling internal erosion of a base soil and the filtration through a downward granular filter. The results of experimental hole erosion tests conducted on base soils show a high resistance of the soils against erosion, and a linear enlargement of the hole was recorded. Moreover, usual guidelines indicate a slow to extremely slow erosion of tested core soils and classified as being highly resistant to erosion. The results from combined erosion–filtration tests provide a method on quantitative measurement of the filtration efficiency and particle size selection. Experiments involving previously dried core soils reveal that the desiccation step makes the soil more susceptible to erosion, indicating that drought phase may affect strongly the core resistance against erosion in dams.