22-27 September 2019
Trade Fairs and Congress Center (FYCMA)
Europe/Madrid timezone

Characterizing the linkage between soil moisture dynamics and discharge at a karst region in Southwest Germany

26 Sep 2019, 15:15
15m
Multiuse room 1 ()

Multiuse room 1

Oral Topic 7 - Karst Hydrogeology Parallel

Speaker

Romane Berthelin (Chair of Hydrological Modeling and Water Resources, University of Freiburg)

Description

Karst groundwater represents an important source of drinking water for the world’s water supply. The most typical approach to characterize a karst system is the disintegration and analysis of its output signal measured at the karst spring using, for example, discharge observations, hydrochemical signal or tracer information. However, the value of soil moisture observations to identify and characterize karstic recharge processes has been receiving limited attention. In this ongoing study, we explore the usability of soil moisture observations to characterize the input signal to the aquifer, i.e. the karstic groundwater recharge dynamics. At a test site at Southwest Germany, observations of climate, soil moisture (90 profiles, at 10cm and 20cm depth, distributed across forest and grassland), and discharge are available. In order to analyze this large data set, we use an automatic routine to extract all soil moisture-discharge events. We hypothesize that recharge initiates after the saturation of the soil, which will be indicated by an increase of discharge. We express this interplay of soil moisture and discharge by hysteresis curves, which vary in shape according to precipitation characteristics, antecedent soil moisture and groundwater conditions. For some of our soil moisture profiles, we find the expected reaction: discharge initiates after soil saturation expressed by a rectangular hysteresis curve. However, at some sites, we find an almost simultaneous reaction of soil moisture and discharge or a reaction of discharge without a soil moisture increase, expressed by a flat shape of the hysteresis curve. We interpret this as the result of preferential flow that occurs close to the soil moisture profile or direct infiltration in the system. Although our analysis and data do yet not provide quantitative information on karstic recharge, it provides new insights into the spatial dynamics of the onset of karstic recharge and the importance of subsurface heterogeneity for the infiltration processes of karst systems.

Primary author

Romane Berthelin (Chair of Hydrological Modeling and Water Resources, University of Freiburg)

Co-authors

Dr Dominic Demand (Chair of Hydrology, University of Freiburg) Prof. Andreas Hartmann (Chair of Hydrological Modeling and Water Resources, University of Freiburg, Germany; Department of Civil Engineering, University of Bristol, UK)

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