Reverse water level fluctuations in semiconfined aquifer systems — “rhade effect”

摘要: Abstract Pumping tests in semiconfined aquifer systems near Dorsten (F.R.G.) caused anomalous reverse water level fluctuations observation wells tapping the overlying confining bed (aquitard) at different depths (multilevel piezometer). Whenever is pumped from a well that screened of “Halterner Sande”, piezometric surface aquitard (“Bottroper Mergel”) rises. After increase, falls according to drawdown head within (Noordbergum effect Verruijt, 1969). Conversely, whenever pump shut off (Rhade effect). The reactions propagate with decreasing amplitude aquifer-aquitard boundary top semipermeable layer. Such (“swelling effects”) may be explained by capability water-saturated, compacted material change volume when subjected sudden pressure changes. On practical basis, Noordbergum and Rhade effects must taken into consideration for evaluating long-term changes chemical hydraulic properties pumped, systems.