Engineering and geological conditions of the north-western territory of Makhachkala due to flooding

Abstract

Relevance. Determination of the geomorphological and geological conditions of the northwestern area of Makhachkala, including the Novolaksky district (Novostroy), in connection with the processes of salinization, alkalinization and flooding of agricultural lands. Currently, the city is intensively expanding in all directions. Particularly interesting is the study area of the northwestern territory of Makhachkala due to flooding. It belongs to the Caspian lowland with negative relief marks. Lack of research on these problems can lead to undesirable material and environmental consequences. Due to flooding, the bearin capacity of the soil also changes. The seismoacoustic properties of soils change, i. e. the velocities of propagation of longitudinal (Vp) and transverse (Vs) waves, as well as the corresponding coefficients and decrements of their absorption. Aim. Determine the boundaries of poorly drained and very poorly drained zones, which reveal barrage areas of the territory, and hydrogeological areas, depending on the water permeability of the composite upper and lower soil strata. Methods. Collecting a database of geotechnical surveys on the chemical composition of groundwater and lithology of cover layers of soils. Collecting hydrogeological parameters of different types of soils and granulometric composition of sands in order to interpret their filtration properties. Determination of the slope of the terrain in order to identify the drainage zones of the territory. Results. Presented are tables of the chemical composition of groundwater for 19 objects and hydrogeological conditions of the area according to engineering and geological surveys for 39 objects, including the depth of groundwater, the type of soil in terms of seismicity, the depth of bedrock, three taxa of hydrogeological regions, slopes of the relief. For the selected hydrogeological regions: GR-1 – a horizontal type of drainage is recommended, for GR-2 – vertical or combined types of drainage, for GR-3 – underground drainage is not effective. It is indicated that it is necessary to seismic microzoning not only of the investigated area, but of the entire city of Makhachkala with the prospect of further development.