Modelling discharge through artesian springs based on a high‐resolution piezometric network

Abstract

Artesian springs are localized aquifer outlets that originate when pressurized ground water is allowed to rise to the surface. Computing artesian discharge directly is often subject to practical difficulties such as restricted accessibility, abundant vegetation or slow flow rates. These circumstances call for indirect approaches to quantify flow. This paper presents a method to estimate ground water discharge through an upwelling spring by means of a three‐layer steady‐state groundwater flow model. Model inputs include on‐site measurements of vertical sediment permeability, sediment temperatures and hydraulic gradients. About 70 spring bed piezometers were used to carry out permeability tests within the spring sediments, as well as to quantify the hydraulic head at different depths below the discharge point. Sediment temperatures were measured at different depths and correlated to permeabilities in order to demonstrate the potential of temperature as a substitute for cumbersome slug tests. Results show that the spatial distribution of discharge through the spring bottom is highly heterogeneous, as sediment permeability varies by several orders of magnitude within centimetres. Sensitivity analyses imply that geostatistical interpolation is irrelevant to the results if field datasets come from a sufficiently high resolution of piezometric records. Copyright © 2013 John Wiley & Sons, Ltd.

The Upwelling Water Flux Feeding Springs: Hydrogeological and Hydraulic Features

“…A minimum and maximum hydraulic gradient (0.026 and 0.15, respectively), as previously estimated, will now be considered. Figure 17 shows the hydraulic gradient estimated in depth, extrapolating the hydraulic head measured in P5 and P6 wells ( Figure 12a); the top of the karst substratum can be estimated by Equation (6), and thus the hydraulic head ranges into karst substratum would be ∆h 1 ≈ 40 m. This value is slightly lower than 48 m found in well S1 located in the recharge zone ( Figures 3, 4 and 16), according to water path into karst aquifer, from the recharge zone to karst substratum below the alluvial deposits. However, as data sets cover different periods, a more specific link between water level recorded in the Piana del Dragone (2002)(2003)(2004)(2005)(2006) and piezometers of Sabato valley (1963)(1964)(1965)(1966)(1967)(1968)(1969) could not be allowed.…”

“…The ascendant flux occurring in the discharge area can lead to the start-up of a river, especially in the karst mountain areas, where powerful springs are fed by a wide catchment which supports high discharge for the entire hydrological year. In other cases, rivers increase their discharge when crossing zones are characterized by ascendant groundwater flow [6].…”

Karst springs of Apennines typified by upwelling flux

“…Il flusso ascendente che si verifica nella zona di recapito dà luogo ad una manifestazione sorgentizia, specialmente nelle aree dei massicci carsici, dove potenti sorgenti basali sono alimentate da ampi sistemi acquiferi che supportano elevate portate durante l'intero anno idrologico. In altri casi, i fiumi incrementano la loro portata quando attraversano zone caratterizzate da flussi ascendenti delle acque sotterranee (Martínez-Santos et al 2014), Gli acquiferi carsici, caratterizzati da una elevata trasmissività e da una elevata capacità di immagazzinare grandi volumi d'acqua, possono consentire una profonda circolazione idrica che genera flussi ascendenti nelle zone di recapito ove sono ubicate le sorgenti basali. DOI 10.7343/as-2018-362 Questi aspetti di carattere idraulico risultano di particolare importanza nella progettazione delle opere di captazione, nella manutenzione delle stesse, nonché per la definizione delle aree di salvaguardia delle sorgenti stesse.…”