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Soils, rocks, and groundwater
Published in Rodrigo Salgado, The Engineering of Foundations, Slopes and Retaining Structures, 2022
We have seen throughout this chapter how soils and rocks have voids; so, water from rain and snow, and from streams, lakes, and oceans continuously enters and leaves the pores (and other voids) of soils and rocks. Groundwater may exist in soils under essentially hydrostatic conditions, or it may flow through the soil pores. If the soil is not capped at the top by an impervious layer, a water table exists. The water table is the surface at which the pore pressures are equal to zero. Under hydrostatic conditions, it is a level surface; otherwise, it is a sloping surface. The determination of the location of the water table or the establishment of any hydrodynamic conditions is important in the solution of any geotechnical problem.
Covers with Capillary Barrier Effects
Published in Bruno Bussière, Marie Guittonny, Hard Rock Mine Reclamation, 2020
Climatic conditions can affect the level of water table and its seasonal variations. In a temperate boreal climate, the water table tends to be at its highest after spring thaw, when recharge is high, while it reaches its lowest level during summer, when precipitation is low and evaporation is high. The CCBE needs to be designed to be efficient when the water budget is the least favorable, that is, during “dry” conditions. A well-designed CCBE will be able to maintain a nearly saturated MRL even during a dry period as long as the suction at the upper CBL–MRL interface remains below the AEV of the fine moisture-retaining material. If the suction becomes higher than the AEV, loss of water from the MRL could occur by drainage and evaporation. The thickness of the MRL ensures that, even if some desaturation occurs, a large portion of the layer remains at a high degree of saturation (>85%).
Principles of Groundwater Flow
Published in Pat M. Cashman, Martin Preene, Groundwater Lowering in Construction, 2020
Generally, a ‘water table’ will exist at some depth below the ground surface; below the water table, the soil and rock pores and fractures are full of water (and are said to be saturated). Above the water table, in a free-draining soil such as a sand or gravel, the pores and fractures are unsaturated – that is, they contain both water and air. However, in very fine-grained soils such as silts or sands, soil capillary forces may retain water in the soil pores above the ‘water table’. In such cases, a capillary saturated zone is said to exist above the water table (see Section 3.3.5).
Functions and performance of sensors for slope monitoring in opencast coal mines – laboratory experimentation
Published in Petroleum Science and Technology, 2023
Sathish Kumar Mittapally, Ram Chandar Karra
The soil moisture content of a slope is majorly accounted for slope instability and is known for reducing the strength of the slope (Abebe, 2020). The major contributor to the increase in the water table is rainfall. Yuliza et al. (2016) say that as rainfall’s duration and intensity rise, water penetration into the soil increases, it causes a surge in the weight and pores of the soil, and the slope becomes unstable. A slight intensification in the moisture content may lead to a lessening slope strength and deformability (David, 2002; Lamotte et al. 1997). A rain gauge measures rainfall but requires a threshold value of precipitation in the local area (Cahe & Kim, 1986). Besides, the water penetration rate will not be similar in all parts of the slope; thus, the dimension of soil moisture is essential for the investigation of slope stability (Bovolenta et al. 2020). The moisture content of the soil, either in dry or wet conditions, can be feasibly overviewed by a soil moisture sensor (Susanto et al. 2019).
Risks related to groundwater in the Murray Darling Basin
Published in Australasian Journal of Water Resources, 2023
Andrew Ross, Ray Evans, Rebecca Nelson
As water scarcity increases, more thorough, detailed, integrated and adaptive groundwater and surface water management in the MDB is required in response to climate and socioeconomic change. Climate change is leading to reduced rainfall, and proportionately greater declines in run-off and recharge in the Basin (Chiew 2006; Barron et al. 2011). This will lead to declining water tables and reduced connectivity between surface water and groundwater, especially under prolonged dry conditions, but there is considerable uncertainty and gaps in knowledge about the impacts of climate change on water resources and catchment streamflows, particularly during droughts (Walker et al. 2021).
Digital maps of mechanical geotechnical parameters using GIS
Published in Cogent Engineering, 2020
Asad H. Aldefae, Jareer Mohammed, Hiba D. Saleem
Once the soil layer is found under the water level, it will obviously be fully saturated. The water table is the upper level of the water in the soil layer for the saturated zone. As described earlier in this paper, the water level is measured from the borehole (24 h) after the end of the drilling process to permit the water to be at a static state due to suction and filtration from the walls of the borehole. These measurements have been taken at different seasonal times during the year.