The World Karst Aquifer Mapping project: concept, mapping procedure and map of Europe

Abstract

Karst aquifers contribute substantially to freshwater supplies in many regions of the world, but are vulnerable to contamination and difficult to manage because of their unique hydrogeological characteristics. Many karst systems are hydraulically connected over wide areas and require transboundary exploration, protection and management. In order to obtain a better global overview of karst aquifers, to create a basis for sustainable international water-resources management, and to increase the awareness in the public and among decision makers, the World Karst Aquifer Mapping (WOKAM) project was established. The goal is to create a world map and database of karst aquifers, as a further development of earlier maps. This paper presents the basic concepts and the detailed mapping procedure, using France as an example to illustrate the step-by-step workflow, which includes generalization, differentiation of continuous and discontinuous carbonate and evaporite rock areas, and the identification of non-exposed karst aquifers. The map also shows selected caves and karst springs, which are collected in an associated global database. The draft karst aquifer map of Europe shows that 21.6% of the European land surface is characterized by the presence of (continuous or discontinuous) carbonate rocks; about 13.8% of the land surface is carbonate rock outcrop.

Fresh Submarine Groundwater Discharge to the Near‐Global Coast

“…Simplifying assumptions in the water budget calculation also contribute to uncertainties. Our estimates of fresh SGD are likely low under several conditions: (1) in layered unconfined‐confined aquifer systems, where a fraction of fresh SGD originates from deeper confined aquifers with more distal recharge zones; (2) in dry coastal regions which tend to receive groundwater import from upland basins (Schaller & Fan, ); (3) in karst, which represents 10% of the world's aquifers (Chen et al, ) and has complex patterns of recharge and conduit flow. Our estimates are likely high under other conditions: (1) in areas where groundwater discharges to unmapped tidal creeks or nearshore wetlands (this discharge is generally not considered “submarine” (Taniguchi et al, ), but is included with fresh SGD in the water budget method) and (2) in areas of intense groundwater extraction, which deducts from fresh SGD but can also enhance recharge.…”

Late Quaternary Variations in the South American Monsoon System as Inferred by Speleothems—New Perspectives Using the SISAL Database

“…Further, climate reconstructions are essential in understanding ecological and biogeographical responses to past hydrologic change in regions such as the Amazon rainforest, Pantanal, caatinga (Brazilian savannah), Cerrado, and Atlantic forests, which are among the regions with the richest biodiversity on Earth. [6]). Green triangles indicate study sites in the region identified by the Speleothem Isotopes Synthesis and Analysis (SISAL) working group but not included in the current version of the database, while purple circles show sites that are already in SISAL_v1 [3].…”

Sulfate variations as a natural tracer for conduit‐matrix interaction in a complex karst aquifer

“…Water from these karst areas contributes significantly to the water supply of many countries. In Austria, 25% of the land surface is covered by carbonate rocks (Chen et al, ), and over 50% of the population, including large cities, such as Vienna, Salzburg, and Innsbruck, depend on drinking water from karst aquifers (Kralik, ). In view of increasing water demand, high alpine karst aquifers in particular offer an enormous potential for future water supply.…”