Dynamics of the Flow Exchanges between Matrix and Conduits in Karstified Watersheds at Multiple Temporal Scales

Abstract

The focus of this paper is to investigate the ability to assess the flow exchanges between the matrix and the conduits in two karstified watersheds (Aliou and Baget, Ariège, France) using the KarstMod modeling platform. The modeling is applied using hourly and daily time series. First, the flow dynamics between the conduit and the surrounding matrix are described on a rainfall event scale (i.e., a few days). The model allows us to describe a physical reality concerning the flow reversal between matrix and conduit when there is a significant rainfall event. Then, the long-term trends (i.e., inter-annual) in the matrix water level are evidenced using the moving average over shifting horizon method (MASH). The mean water level in the matrix dropped about 10% to 15% since the late 1960s. Also, the matrix recharge has been delayed from February in the late 1960s to April since the 1990s. Moreover, the contribution of the matrix in the total spring flow is estimated though mass balance. It is estimated that the annual matrix contribution in the total spring flow is about 3% and it can increase to up to 25% during periods with low rainfall.

Coupling SKS and SWMM to Solve the Inverse Problem Based on Artificial Tracer Tests in Karstic Aquifers

“…This constitutes a strong hypothesis, but it seems to be acceptable over the Baget area. It was estimated, through a conceptual reservoir model, that the reservoir corresponding to the matrix contributes about 10% in the total spring discharge [62] and the tracer velocity measured by Sivelle and Labat [13] is characteristic of conduit dominated karstic aquifers [63].…”

Nossana Spring (Northern Italy) under Climate Change: Projections of Future Discharge Rates and Water Availability

“…The model ensemble returns better results in terms of the maximum number of consecutive days below the thresholds, which are slightly underestimated with the exception of the lower threshold during the calibration period. Specifically, for the calibration period and the 1.32 m 3 s −1 (1.52 m 3 s −1 ) threshold, this index is calculated as 10 (46) days for observations and 58-63 (35)(36)(37)(38)(39)(40)(41)(42)(43)(44) days for the model ensemble. The consecutive number of days below the threshold can therefore be considered the most reliable parameter to evaluate the future behavior of the Nossana Spring and discuss its future management.…”

“…Input-output models can be used to relate the precipitation contribution to the outflow through empirical equations based on lumped parameters (e.g., [30,31]), neural networks (e.g., [32]), or input-response functions (e.g., [33,34]). An increasing number of studies involving such modelling approaches have been documented for karst environments in recent years (e.g., [35][36][37][38][39]). Due to the lack of physical processes representation, a limitation of these models concerns their loss of reliability if applied in conditions that largely differ from calibration [40,41].…”

Hydraulic Behavior of Karst Aquifers

“…Sivelle et al [6] analyzed the ability to assess the flow exchange between the matrix and the conduits in two karstified watersheds in France (i.e., Aliou and Baget) using the karstMod modelling platform. The model highlights a physical reality concerning the flow reversal between the matrix and the conduit during a significant rainfall event.…”