Hydrogeological study and numerical model of groundwater rise mitigation actions effects in the glacial - fluvioglacial territory of Grandate (Como, north Italy)

Water levels rising, Grandate, Italy, transient numerical mode

Tunnel Inflow Monitoring in Permeable Rocks Nearby Cannero River, Piedmont (Northern Italy)

Analytical methods used in engineering practice for a preliminary tunneling design do not adequately account for the domain limitation due to a river. In order to forecast the flow rate that has to be extracted to reach a sustainable water head in tunnel, the design must consider the changes of river hydrometric level and their consequences on piezometric head. The river is taken in account and the constraints of analytical solutions are discussed assuming isotropic and infinite domain. In particular, the study develops a formulation considering the variation of hydrograph in the river and different location of tunnel in the aquifer nearby the stream. Then, this equation was applied to a preliminary tunneling design in Cannero Valley, Northern Italy (Piedmont). The results, compared with analytical model's ones show that the analytical approach leads to a good estimation of the tunnel inflow and, the analytical to a preliminary evaluation of its most suitable location

Hydrogeological study of the glacial-fluvioglacial territory of Grandate (Como, Italy) and stochastical modeling of groundwater rising

On November 2014, the Municipality of Grandate, near Lake Como, had to deal with a great emergency that was caused by the flooding of factory undergrounds. The authors realized a hydrogeological study to understand the causes of groundwater flooding and to prepare a pre-feasibility study concerning possible actions for groundwater control. The hydrogeological structure is rather complex and required time-consuming reconstruction of the conceptual site model. A transient numerical model was developed to analyse the system behaviour in different scenarios. The flow model was calibrated in a steady and unsteady-state using the automatic calibration code Model-Independent Parameter Estimation (PEST). The study demonstrated that the reason for floods was mainly due to the concurrence of three causes: (1) the hydrogeological structure of the area was recognized as a stagnation zone, (2) groundwater rising, and (3) extremely heavy rainfall in 2014. Through the PEST RandPar function, 100 random rainfall scenarios were generated starting from rainfall data for the last 20 years. The model was used to run 100 1-year long simulations considering the probability distribution of recharge related to the 100 randomly generated rainfall scenarios. Through collecting the piezometric heads that resulted from the simulations, monthly probability curves of groundwater exceeding a threshold level were obtained. The results provided an occurrence probability of groundwater level exceeding the underground structures level between 12% and 15%

Analytical method for stagnation point calculation: theoretical developments and application to a hydraulic barrier design (Sicily, Italy)

A stagnation point is any point in the aquifer where the fluid velocity is equal to zero. Stagnation points can occur where the flow encounters impermeable surfaces or where the potentiometric surface is nearly horizontal. The presence of stagnation points is useful to locate groundwater bodies characterized by a very long renewal time