evaluation of geotechnical properties of sediments of the top layer of hypersaline lakes: the case of lake urmia

This research mainly sought to evaluate the sediments of the urmia lake bed at three different locations on the lake. identification tests, organic content, specific gravity tests, saturated hydraulic conductivity, and hydraulic gradient tests were performed to assess the geotechnical properties of soil at three different areas along lake urmia namely hyderabad, chichest, and urmia-tabriz bridge. the results showed that the soil type varied from coarser to finer in sediment particle size from the estuarine zone of the rivers to the lake’s interior. the type of soil was identified for three areas of urmia-tabriz bridge, chichest, and hyderabad ml, sp-sm, and sp-ml, respectively. the shallow depth of lake leads to an almost uniform distribution oforganic materials in the lake sediment, with a slightly higher value along the shorelines. compared to inorganic soils, the presence of organic material reduced the gs value in the lake bottom to 17.82%. this increases the risk of bed mud creep due to the low hydraulic gradient beneath any structures intended to reduce the lake’s size sustainably through river discharge and evaporation. in the southern parts, the average hydraulic conductivity for finer soils near the lake’s shore was between 57 and 127 cm/day for coarse material. the critical hydraulic gradient in the southern area varied from 1.65 for the lake shore to 0.95 up to 3 km into the lake. in the northern area, far from the mouth of the main tributaries, the values varied between 1.9 and 0.75 for the same distances, giving a zonal map of lake urmia’s bottom sediment properties. the results of this study allow a first estimation of the geotechnical characteristics of a hypersaline lake to choose an appropriate structure, such as sheet piles.