Karst aquifers provide drinking water for 10% of the world's population, support agriculture, groundwater-dependent activities, and ecosystems. These aquifers are characterised by complex groundwater-flow systems, hence, they are extremely vulnerable and protecting them requires an in-depth understanding of the systems. Poor data accessibility has limited advances in karst research and realistic representation of karst processes in large-scale hydrological studies. In this study, we present World Karst Spring hydrograph (WoKaS) database, a community-wide effort to improve data accessibility. WoKaS is the first global karst springs discharge database with over 400 spring observations collected from articles, hydrological databases and researchers. The dataset's coverage compares to the global distribution of carbonate rocks with some bias towards the latitudes of more developed countries. WoKaS database will ensure easy access to a large-sample of good quality datasets suitable for a wide range of applications: comparative studies, trend analysis and model evaluation. This database will largely contribute to research advancement in karst hydrology, supports karst groundwater management, and promotes international and interdisciplinary collaborations. Background & Summary Karst aquifers are essential sources of drinking water to about 10% of the world's population 1. In many regions across the globe, karst groundwater is also an indispensable resource for ecosystems, agriculture and, economic activities, as well as for tourism and recreation 2,3. For example, in Europe, 21.6% of the land surface is underlain by carbonate rock 4 which contributes up to 50% of supplied drinking water in some countries 5-7. However, groundwater flow in karst aquifers is characterised by a complex interplay of fast-flowing conduit and slow-flowing matrix systems 8,9. Hence, the storage capacity of karst aquifers is variable and systems are extremely vulnerable to climatic pressures, human impacts and contamination 10. In order to ensure adequate protection of karst water sources, in-depth hydrogeological knowledge is necessary. Large-scale modelling and comparative water resource research have shown the great value of large datasets in hydrology 11. Numerous studies have applied these large datasets for several purposes such as model evaluation, global parameter estimations, impact studies, statistical and comparative analyses. For instance, large-scale hydrological models such as WaterGAP 12 used discharge data from the Global Runoff Data Centre (https://www. bafg.de/GRDC) for parameter estimation. Likewise, streamflow data from the Model Parameter Estimation Experiment (MOPEX) 13 and the Global Runoff Data Centre (GDRC) were combined to derive global base flow indexes and recession constants 14. Streamflow observations of near-natural catchments obtained from UNESCO's European Water Archive (EWA) were used to investigate the streamflow trends across Europe and differentiated the impacts from climatic variability and anthropogenic dri...
Abstract. The sensitivity of terrestrial environments to past changes in heat transport is expected to be manifested in Holocene climate proxy records on millennial to seasonal timescales. Stalagmite formation in the Okshola cave near Fauske (northern Norway) began at about 10.4 ka, soon after the valley was deglaciated. Past monitoring of the cave and surface has revealed stable modern conditions with uniform drip rates, relative humidity and temperature. Stable isotope records from two stalagmites provide time-series spanning from c. 10 380 yr to AD 1997; a banded, multi-coloured stalagmite (Oks82) was formed between 10 380 yr and 5050 yr, whereas a pristine, white stalagmite (FM3) covers the period from ∼7500 yr to the present. The stable oxygen isotope (δ 18 O c ), stable carbon isotope (δ 13 C c ), and growth rate records are interpreted as showing i) a negative correlation between cave/surface temperature and δ 18 O c , ii) a positive correlation between wetness and δ 13 C c , and iii) a positive correlation between temperature and growth rate. Following this, the data from Okshola show that the Holocene was characterised by high-variability climate in the early part, lowvariability climate in the middle part, and high-variability climate and shifts between two distinct modes in the late part.A total of nine Scandinavian stalagmite δ 18 O c records of comparable dating precision are now available for parts or most of the Holocene. None of them show a clear Holocene thermal optimum, suggesting that they are influenced by annual mean temperature (cave temperature) rather than seasonal temperature. For the last 1000 years, δ 18 O c values display a depletion-enrichment-depletion pattern commonly interpreted as reflecting the conventional view on climate Correspondence to: H. Linge (henriette.linge@geo.uib.no) development for the last millennium. Although the δ 18 O c records show similar patterns and amplitudes of change, the main challenges for utilising high-latitude stalagmites as palaeoclimate archives are i) the accuracy of the age models, ii) the ambiguity of the proxy signals, and iii) calibration with monitoring data.
In the past 100 years, a decreasing rainfall trend has been recorded on Romanian territory, a trend that continues today. Therefore, realistic estimation of the groundwater resources is crucial, especially for the rural communities lacking the economic power to use alternative sources of drinking water. The groundwater sources used by rural communities in Romania generally originate directly from caves, wells or springs with no proper evaluation of the water quality. Groundwater is exposed to different pollutants, as bats' guano in caves, fertilizers in agricultural areas or livestock (cattle, sheep, goats, etc.) farms on the surface. On the other hand, the water extracted directly from inside the caves is affecting groundwater ecosystems, highly vulnerable to any human impact and neglected by European legislation so far. The project aims to monitor, during two consecutive years, groundwater sources with different degrees of above- and underground pollution, from different regions of Romania. To achieve the goals of the project, a multidisciplinary monitoring strategy that will include measurements of hydrological, physico-chemical and biological (microbiology and aquatic invertebrates’ assessment) parameters alongside the quantification of radon and stable isotopes, rainfall or possible inflows of water. The specific outcomes of this project are: i) to test, develop and validate a new, more rapid and efficient method for monitoring and risk assessment of groundwater sources – and not only – by using molecular techniques, and propose this method to the water agencies in Romania; ii) to propose for Romanian authorities to implement a harmonized coherent methodology to measure radon concentration in water, as a consequence of EURATOM Directive; and iii) to educate local communities that are using groundwater as source for drinking water and raise young people’s awareness on the benefits of ecosystem services provided by the groundwater.
Background Subarctic regions are particularly vulnerable to climate change, yet little is known about nutrient availability and biodiversity of their cave ecosystems. Such knowledge is crucial for predicting the vulnerability of these ecosystems to consequences of climate change. Thus, to improve our understanding of life in these habitats, we characterized environmental variables, as well as bacterial and invertebrate communities of six subarctic caves in Northern Norway. Results Only a minuscule diversity of surface-adapted invertebrates were found in these caves. However, the bacterial communities in caves were compositionally different, more diverse and more complex than the nutrient-richer surface soil. Cave soil microbiomes were less variable between caves than between surface communities in the same area, suggesting that the stable cave environments with tougher conditions drive the uniform microbial communities. We also observed only a small proportion of cave bacterial genera originating from the surface, indicating unique cave-adapted microbial communities. Increased diversity within caves may stem from higher niche specialization and levels of interdependencies for nutrient cycling among bacterial taxa in these oligotrophic environments. Conclusions Taken together this suggest that environmental changes, e.g., faster melting of snow as a result of global warming that could alter nutrient influx, can have a detrimental impact on interactions and dependencies of these complex communities. This comparative exploration of cave and surface microbiomes also lays the foundation to further investigate the long-term environmental variables that shape the biodiversity of these vulnerable ecosystems.
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Maze caves or network caves are enigmatic in their evolution, as they form flow nets rather than more efficient, direct point-to-point flow routes. Network caves are often characterized by uniform passage dimensions in several directions, which indicates simultaneous dissolution of most available fractures. Nonshauggrotta in Gildeskål, northern Norway, is formed in low-dip marble strata and situated as a relict in a topographical and hydrological hanging position, thus lacking a modern drainage area. The cave displays a reticulate network geometry dictated by two orthogonal fracture sets. Passage morphology and paleocurrent marks in the cave walls (scallops) demonstrate that the cave evolved under water-filled conditions (phreatic) and that the relatively slow flow was directed uphill towards the confining aquiclude and the cliff face. In that sense, it has some resemblance to hypogene caves. However, we propose that the cave is a result of ice-contact speleogenesis, as it developed in the lee side of the Nonshaugen ridge under topographically directed glacier flow and seems independent of the otherwise variable flow regimes characteristic of the glacial environment.
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