Analytical modeling of groundwater flow of vertically multilayered soil stratification in response to temporally varied rainfall recharge

Evaluation of hillslope storage with variable width under temporally varied rainfall recharge

10.5194/hess-2021-50 ◽

2021 ◽

Author(s):

Ping-Cheng Hsieh ◽

Tzu-Ting Huang

Keyword(s):

Groundwater Flow ◽

Analytical Solutions ◽

Water Conservation ◽

Numerical Solutions ◽

Integral Transform ◽

Time Discretization ◽

Third Order ◽

Analytical And Numerical Solutions ◽

Rainfall Recharge ◽

Integral Transform Technique

Abstract. This study discussed water storage in aquifers of hillslopes under temporally varied rainfall recharge by employing a hillslope-storage equation to simulate groundwater flow. The hillslope width was assumed to vary exponentially to denote the following complex hillslope types: uniform, convergent, and divergent. Both analytical and numerical solutions were acquired for the storage equation with a recharge source. The analytical solution was obtained using an integral transform technique. The numerical solution was obtained using a finite difference method in which the upwind scheme was used for space derivatives and the third-order Runge–Kutta scheme was used for time discretization. The results revealed that hillslope type significantly influences the drains of hillslope storage. Drainage was the fastest for divergent hillslopes and the slowest for convergent hillslopes. The results obtained from analytical solutions require the tuning of a fitting parameter to better describe the groundwater flow. However, a gap existed between the analytical and numerical solutions under the same scenario owing to the different versions of the hillslope-storage equation. The study findings implied that numerical solutions are superior to analytical solutions for the nonlinear hillslope-storage equation, whereas the analytical solutions are better for the linearized hillslope-storage equation. The findings thus can benefit research on and have application in soil and water conservation.

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Variation of Groundwater Flow Caused by Any Spatiotemporally Varied Recharge

Water ◽

10.3390/w12010287 ◽

2020 ◽

Vol 12 (1) ◽

pp. 287

Author(s):

Ming-Chang Wu ◽

Ping-Cheng Hsieh

Keyword(s):

Analytical Solution ◽

Groundwater Flow ◽

Unconfined Aquifer ◽

Initial Water ◽

The Past ◽

Sloping Aquifer ◽

Taichung City ◽

Spatially Distributed ◽

Recharge Rates ◽

Rainfall Recharge

The objective of this study was to develop a complete analytical solution to determining the effect of any varying rainfall recharge rates on groundwater flow in an unconfined sloping aquifer. The domain of the unconfined aquifer was assumed to be semi-infinite with an impervious bottom base, and the initial water level was parallel to the impervious bottom of a mild slope. In the past, similar problems have been discussed mostly by considering a uniform or temporally varying recharge rate, but the current study explored the variation of groundwater flow under temporally and spatially distributed recharge rates. The presented analytical solution was verified by comparing its results with those of previous research, and the practicability of the analytical solution was validated using the 2012 and 2013 data of a groundwater station in Dali District of Taichung City, Taiwan.

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Remarks on the hydrogeological setting of S. Eufemia Lamezia plain through the development of the top surface of the intermediate confined aquifer (central Calabria)

Acque Sotterranee-Italian Journal of Groundwater ◽

10.7343/as-120-15-0147 ◽

2015 ◽

Vol 4 (3) ◽

Author(s):

Enzo Cuiuli

Keyword(s):

Groundwater Flow ◽

Shallow Aquifer ◽

Direct Transfer ◽

Confined Aquifer ◽

Geological Data ◽

Recharge Rate ◽

Hydrogeological Setting ◽

Artesian Aquifer ◽

Rainfall Recharge ◽

Clay Horizon

The S. Eufemia Lamezia plain, located in central Calabria, is characterized by the presence of a multi-layered aquifer. In particular, it was studied the intermediate artesian aquifer, content in the Pliocene sands and sandstones. The collection of new lithostratigraphic data, related to drilling for water supplies, allowed to draw the map of the top of intermediate artesian aquifer underlying in the study area. The top surface of sands and sandstones map, presented here, seems to confirm the structural-geological data of the surface showing, also in depth, the conditioning of tectonics on the study area and on the groundwater flow. The analysis of the selected stratigraphic data shows that the studied aquifer is constituted by Pliocene deposits of sand and sandstones, confined to the top by Pliocene clay. Therefore locally hydraulic connections with the shallow aquifer for leackage phenomena are possible. The supply of the studied aquifer happens mainly for lateral recharge because the clay horizon that borders with the top of the aquifer prevents direct transfer of rainfall recharge. However, a reduced recharge rate is due to the meteoric recharge, which is possible in limited parts of the territory to the east of the study area and over. Therefore, this study aims to implement the knowledge of the groundwater flow of S. Eufemia plain by returning the top intermediate confined aquifer map which, is little studied but strongly exploited because, respect to the shallow aquifer, is more productive and more protected by potential contamination due to the presence of the aquiclude/aquitard which isolates it by the top.

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Hydraulic properties calibration by high resolution monitoring data and 1D to 3D groundwater flow modeling of the Carozzo Landslide

10.5194/egusphere-egu21-16043 ◽

2021 ◽

Author(s):

Alberto Previati ◽

Giuseppe Dattola ◽

Gabriele Frigerio ◽

Flavio Capozucca ◽

Giovanni B. Crosta

Keyword(s):

Steady State ◽

Groundwater Flow ◽

Material Properties ◽

Hydraulic Properties ◽

Transient State ◽

Primary Concern ◽

Piezometric Level ◽

Piezometric Head ◽

Storage Function ◽

Rainfall Recharge

A reliable modeling of a landslide activation and reactivation requires a representative geological and engineering geological characterization of the affected materials. Beyond the material strength, landslide reactivation is sensitive to groundwater pressure distributions, that are generated by some external perturbation (recharge) and by the hydraulic properties of the materials. Drainage stabilization works generally involve drilling of a large number of drains and, therefore, minimize the total length is of primary concern to reduce the costs.Aim of this work was the calibration of material properties for the optimization of drainage elements to be built for the slope stabilization and the construction of a shallow tunnel crossing a landslide. The case study is represented by the 4.0 &#183; 105 m3 Carozzo landslide (La Spezia, Liguria, Italy) which affects some marly and sandstone formation. During the tunnel excavation a monitoring network consisting of five DMS columns for displacements and piezometric head multilevel measurements was installed. The monitoring provided a series of piezometric head recession curves following some recharge events. The series of data generated in response of a unique perturbation (rainfall recharge event) were chosen to calibrate the material properties through a multi-step approach, starting from a 1D model and progressively approaching a complete 3D model.The 1D simplified approach applies the solution by Troch et al. (2003) that considers a homogeneous landslide material, with constant slope and a progressive change in the slope width. In this model a storage function considers the amount of water stored in a slope section. By imposing the continuity equation and the Darcy law a second order of partial differential equation is solved by integration in space and time. By taking the initial conditions from piezometric measurements and assuming a constant rainfall recharge, the piezometric level and the outflow rate were computed and compared with the local piezometric level time history, by changing the hydraulic conductivity and the storage function value.Successively, a groundwater flow FEM numerical model (in 2D and 3D) was developed considering the landslide geometry and internal zonation, including the presence of the excavated part of the tunnel. The model domain was divided into sub-zones according to the available geological surveys to account for internal variations of the material properties. The steady-state simulation of the water flow allowed to estimate the equivalent hydrogeological parameters of each subdomain. The hydraulic head distribution obtained under steady-state conditions was used as initial condition for the transient-state simulation. The recharge from precipitation was also included in the water balance by means of daily rainfall time-series. Finally, the model parameters were calibrated in transient state by comparing measured data and simulated results.The minimum error between simulated and measured piezometric heads under transient conditions was obtained through the 3D configuration. Calibrated hydraulic conductivities in the 3D solution are up to an order of magnitude lower than the 1D solution because of the homogenous assumption of the model. The internal zonation of the landslide body and the modeling of a low-conductivity shear zone were essential to explain the pressure differences inside the body.

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