Introduction
Study site
Data and methods
Karst discharge data
Climate data
Station ID | Longitude [° E] | Latitude [° N] | Elevation [m asl] | Data length | Climate variables |
---|---|---|---|---|---|
2814 | 9.7644 | 48.5122 | 687 | 1952–2021 | P |
5511 | 9.6187 | 48.5206 | 825 | 1952–2021 | P |
537 | 9.7443 | 48.4369 | 705 | 1952–2021 | P |
3402 | 9.4837 | 48.3851 | 755 | 1952–2021 | P, T, SH, SWE |
4887 | 9.8648 | 48.6656 | 734 | 1952–2016 | T, SH, SWE |
2949 | 9.5275 | 48.5396 | 758 | 1952–2001 | T, SH, SWE |
Statistical analysis
Karst discharge modelling
Historical simulation
Simulation of future climate change impacts
Results
Karst system hydrodynamics
Discharge and climate trends
Items | Minimum | Mean | Maximum |
---|---|---|---|
Σ P [mm] | 640 | 950 | 1,288 |
Σ PET [mm] | 497 | 552 | 629 |
Σ (P-PET) [mm] | 143 | 398 | 659 |
T [°C] | 5.4 | 7.0 | 8.9 |
Q [m3 s−1] | 1.3 | 2.3 | 4.0 |
The impact of snowmelt on discharge
Timing
Intensity
Items | Minimum | Mean | Maximum |
---|---|---|---|
Peak snow accumulation [mm] | 16 | 60 | 181 |
Total snowfall [mm] | 19 | 132 | 295 |
Total precipitation [mm] | 640 | 950 | 1,288 |
Number of days covered in snow | 22 | 81 | 152 |
Qmax [m3 s–1] | 4.5 | 13.6 | 32.6 |
Karst discharge simulation in the past and future
Discussion
Karst system structure
Reliability of the groundwater model
Trends and mechanisms
Implications
Conclusions
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The Blautopf karst system, with a memory of 40 days, consists of both fast and slow flow paths that enable the discharge to respond quickly to precipitation in 3 days. The fast and slow flow components characterize the unique response of the karst aquifer to climate change and variations.
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The annual and seasonal mean discharge do not show a significant historic trend of changes. The monthly mean discharge shows that the discharge in April (the last month of the snow period) has significantly reduced (−0.02 m3 s−1 year−1) due to decreasing precipitation and increasing air temperature and evapotranspiration. The annual mean discharge is projected to decrease by 4–10% (−0.10 to −0.22 m3 s−1) for the RCPs 2.6, 4.5 and 8.5 by 2100.
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The peak snowmelt plays a key role in generating the discharge maxima of the spring, but it is shown that it will end earlier (shift from March to February), last shorter (−4 days), and become less intense (−35 mm in peak snow accumulation). As a result, the annual peak discharge has shifted towards a low state (<13.6 m3 s−1) under global warming since 1988. The peak discharge may continue decreasing by 50% (−7 m3 s−1) as projected by all scenarios.
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The annual minimum discharge does not indicate a significant historic trend of changes; however, it is projected to decline by 35–55% (−0.17 to −0.27 m3 s−1) for RCPs 2.6, 4.5 and 8.5 due to increasing evapotranspiration.