Tracer test to assess flow and transport parameters of an earth slide: The Montecagno landslide case study (Italy)
Francesco RonchettiLeonardo PiccininiManuela DeianaGiuseppe CiccareseValentina VincenziA. AguzzoliGianluca MalavasiPaolo FabbriAlessandro Corsini
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Keywords:
TRACER
Debris flow
Flow conditions
Preferential flow pathways connect upstream and downstream channels in abandoned mines or seasonally pumping areas. The inactive supply well facilitates contaminant migration between aquifers leading to water quality challenges; it is important to note that the impacts of regional groundwater flow on contaminant migration through pumping wells have not been well elucidated in literature. In the study, we developed a numerical model describing contaminant migration through an inactive supply well that is pumped seasonally influenced by the regional groundwater flow field. The model was developed using the finite-element COMSOL Multiphysics software to estimate the potential threats to water quality. Major findings showed that a larger regional groundwater velocity results in lower concentration of contaminant. In addition, during pumping, a smaller recovery ratio inside the wellbore facilitates the deterioration of water quality in the deep aquifer. Furthermore increasing pumping frequency can effectively prevent contamination and improve the water quality in the deep aquifer. Similarly, higher pumping rate leads to a larger capture zone, which can significantly improve the water quality in the deep aquifer. The general conclusion is that the regional groundwater flow has a negative impact on the quality of groundwater extracted by seasonally pumping well.
Multiphysics
Flow conditions
Water well
Groundwater model
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Most groundwater equations for flow toward wells use a set of assumptions and idealizations about the aquifer–well configuration so that analytical expressions can be derived for steady-state and unsteady-state flows. In this article, the main assumption in these equations is that constant hydraulic conductivity is relaxed and instead allows radial variability. The basic question is how the hydraulic conductivity gradient affects groundwater flow. Changes in hydraulic conductivity influence groundwater flow; any local changes in the hydraulic conductivity cause local changes in hydraulic gradient and in groundwater velocity. This problem is solved using water balance equations with changes in linear radial hydraulic conductivity. Simple but more general equations for groundwater flow toward wells are derived and applied to steady-state groundwater flows in a confined aquifer. This formulation reduces to the classical Theim solution for constant hydraulic conductivity. The use of this methodology is presented for steady-state groundwater measurement from a well in the Arabian Peninsula. It is observed that constant hydraulic conductivity underestimates transmissivity, compared to the numerical example given in this article, by about 41%.
Groundwater flow equation
Slug test
Groundwater model
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Abstract The present work provides new insights on some factors controlling the groundwater flow in low‐permeability media affected by deep Apennine landslide, involving several million cubic meters of soil and rock. Rainfall and groundwater circulation are among the major triggers of landslides. However, if the first factor is well studied, only few research deal with the hydrogeological processes in the landslide. Thus, in this study, combined hydrogeological, geochemical and isotopic investigation were performed in order to: (1) characterize infiltration and flow processes and (2) understand the role of sliding surface on groundwater circulation in a complex landslide that mainly involves sandstones and clay materials. Results indicate that at least two circuits coexist: a faster one, where rainfall preferentially infiltrates and flows in a well‐connected network of macropores, cracks and soil pipes, which mainly feeds the springs; a slower and a deeper one that flows in the soil matrix and fractures of the landslide body. Moreover, the investigated slip zones show an aquiclude characteristic in terms of groundwater circulation, where the flow is very slow and precipitation influence is negligible. These results could be helpful in an accurate slope stability considerations and to improve the reliability of landslide risk assessment.
Infiltration (HVAC)
Macropore
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Abstract A three‐dimensional finite difference model was developed to study the groundwater flow system in an upland area bordering a lake. For a general perspective of the groundwater flow system, a steady state three‐dimensional flow was employed. Having determined the flow net by using a three‐dimensional model, the flow volumes under natural conditions have been used to establish the parameter values and for the analyses of flow patterns. Further, to study the effects of human impact and precipitation on groundwater flow conditions in a small area, a transient three‐dimensional simulation was performed. Environmental tritium was used to trace the regional groundwater movement to verify the three‐dimensional mathematical model. Results obtained using the three‐dimensional mathematical model approach and tritium concentration analyses were in close agreement. The results demonstrated that the groundwater flow system should be analysed using a three‐dimensional geometric concept of groundwater movement.
Flow conditions
Groundwater model
Groundwater discharge
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