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Qualitative Correlations between Antecedent Rainfall and Landslip Frequency on Thin Shale Beds
Published in Mark Anglin Harris, Confronting Global Climate Change, 2019
Nevertheless, despite the above evidence, antecedent rainfall is often unimportant in triggering landslips. Evaluating the influence of antecedent rainfall and hydraulic conductivity on landslides triggered by rainfall using the SHIA_Landslide model (Aristizabal et al. 2016), Aristizabal et al. (2016) determined that soils of high hydraulic conductivity values only need short and intense rainstorms for failure and that antecedent rainfall conditions do not play an important role for these kinds of soils. The phreatic zone is where soil is saturated with water, and is the counterpart of the vadose zone, or unsaturated zone, above. Thus, they found that whereas the increase in preceding rain in the three months prior to the September 21, 1990, event did not generate any significant change in the peak of the phreatic level for the cells evaluated, and nor did the increase in antecedent rain during the previous 24 hours to the event, they concluded that the absence of any changes in the phreatic level signified a high hydraulic conductivity which removed any chance of lingering water from antecedent rainfall in the soil.
Water Resources Engineering
Published in P.K. Jayasree, K Balan, V Rani, Practical Civil Engineering, 2021
P.K. Jayasree, K Balan, V Rani
In hydrogeology, groundwater flow is defined as the “part of stream flow that has infiltrated the ground, has entered the phreatic zone, and has been discharged into a stream channel, via springs or seepage water.” It is governed by the groundwater flow equation. Groundwater is water that is found underground in cracks and spaces in the soil, sand, and rocks. An area where water fills these spaces is called a phreatic zone or saturated zone. Groundwater is stored in and moves slowly through the layers of soil, sand, and rocks called aquifers. The rate of groundwater flow depends on the permeability (the size of the spaces in the soil or rocks and how well the spaces are connected) and the hydraulic head (water pressure).
Common Properties of Chemicals of Concern and Soil Matrices
Published in Cristiane Q. Surbeck, Jeff Kuo, Site Assessment and Remediation for Environmental Engineers, 2021
Cristiane Q. Surbeck, Jeff Kuo
A leaking UST is illustrated in Figure 2.5. The vadose zone (also called the unsaturated zone, or zone of aeration) is the subsurface between the ground surface level (gsl) and the water table. The soil in the vadose zone is not fully saturated with water; in other words, the pores contain both air and water. Below the water table is the phreatic zone, in which the soil is saturated with water (i.e., the aquifer). The water table is the interface between the vadose zone and the uppermost aquifer.
Subaerial disconformities, microkarst and paleosols in Ordovician limestones at Bowan Park and Cliefden Caves, New South Wales, and their geoheritage significance
Published in Australian Journal of Earth Sciences, 2019
V. Semeniuk, I. G. Percival, M. Brocx
With regard to climate, of particular interest is that these Ordovician limestones are showing a level of solution and rapidity of alteration compared with Quaternary limestones, suggesting that CO2 levels may have been higher than in the Quaternary (Ruddiman, 2001). Further, the groundwater in which the more deeply buried limestones where lodged in the phreatic zone was recharged by slightly acidic meteoric water—this would have driven the dissolution of the carbonate materials. The rapidity of alteration in combination with the depth of delivery of crystal silt suggests that this region in the Ordovician was a high-rainfall zone. In this context, combined with information about the growth of coralline and shelly benthos, the Bowan Park/Cliefden Caves region during the Ordovician was likely to have been in a humid tropical climate (cf. Torsvik & Cocks, 2017).
Geochemical characteristics of rehabilitated tailings and associated seepages at Kidston gold mine, Queensland, Australia
Published in International Journal of Mining, Reclamation and Environment, 2019
Mansour Edraki, Thomas Baumgartl, David Mulligan, Warwick Fegan, Ali Munawar
Seasonal effects of TSF groundwater levels, which could not be detected in the early years due to the continuous fall in the phreatic surface, have been recognised since 2005. More recently (2008–2009), the water levels have returned to the 2003 levels (Figure 6). As rain events are generally heavy, it can be assumed that gravitational water flow in the tailings pore system will occur at close to saturation conditions. However, despite the high infiltration rate into the tailings it seems that the travel time of water towards the phreatic zone is slowed down by layers of tailings sediments with significantly lower hydraulic permeabilities. A dome-shaped aquifer can be inferred from the piezometer measurements with levels lower along the perimeter of the TSF (particularly near the seepage points) compared to the centre.
Characteristics and formation mechanisms of Mesozoic compressional structures in the Huanghua Depression, Bohai Bay Basin, China
Published in Australian Journal of Earth Sciences, 2021
W. Li, F. Zhang, Y. Zhang, L. Fu, H. Li
The Mesozoic tectonic compression was the main factor that improved reservoir properties of buried hills in the Huanghua Depression (Wu et al.,2002). Tectonic compression in the Indosinian was stronger in the north, leading to differences in physical properties of the inner reservoirs of the Paleozoic strata of the northern and southern buried hills in the Huanghua Depression. In the northern region, the mountain strata mainly consist of Paleozoic carbonate rock reservoirs, and upper Paleozoic strata are thin or limited. For example, the Qianmiqiao buried hill was subjected to intense compression and denudation during the Indosinian, and its Lower–Middle Triassic and upper Paleozoic strata are absent. A number of quasi-layered fracture-cavity reservoir zones composed of paleo-phreatic zone formed in the Ordovician Upper Majiagou and the Fengfeng formations, where, although deeply buried in the later stage, they control enrichment and high production of hydrocarbon (Figure 13) (Fu et al., 2016). The lower Paleozoic and upper Paleozoic strata are both present in the southern region. Owing to widespread distribution of Lower–Middle Triassic strata, the Paleozoic reservoirs were subjected to minor leaching and reformation, so the reservoir’s physical properties are poorer than those in the northern region. In the Jurassic and Early Cretaceous, the Huanghua Depression experienced widespread sedimentation, consisting mainly of lacustrine facies sandy mudstone sediments. The uplift and denudation caused by the early and late Yanshanian tectonic compression effectively improved the Jurassic–Cretaceous clastic rock reservoir properties, forming a favourable set of buried-hill reservoirs, e.g. the strata-unconformity reservoirs at the top of Jurassic–Cretaceous in the Wangguantun buried hill (Figure 13).