Karst rivers—these invisible waterways shaped by the dissolution of limestone—play an important role in the hydrology of regions such as Greece, particularly around Argos. Their behavior, which combines slow and rapid flows, poses challenges for water management in a context of chronic drought.
In karst systems, rainwater infiltrates rapidly through sinkholes, fissures, and chasms, passing through an unsaturated vadose zone before reaching the groundwater table. Flow is divided into two components: slow flow within the carbonate rock matrix, and rapid circulation in underground conduits and rivers, which can reach speeds of 500 m/h and cause sudden flooding at the springs.
This process is based on the chemical dissolution of limestone by water, which erodes the rock over thousands of years and forms underground passages. In Argos, in the Peloponnese, the Anavalos and Lerna springs illustrate this hydrology. These karst springs emerge in the Lerna plain and constitute an important resource for the region.
To trace these water flows, one must head up toward the hills of Lerna to the Arcadian Plateau. This valley creates a microclimate that traps cloud cover and receives heavier rainfall than the Argos plain. The seasonal accumulation of water in a closed basin, with no apparent outlet, led to the formation of Lake Taka, whose size varies with the seasons.
Today, the lake is partially dammed, but it still overflows in winter, helping to recharge the karst system. The water seeps into ponors—fissures located along the edge of the depression—and then flows underground toward Lerna.
Similarly, downstream it is possible to observe the manifestations of these water flows. The Kiveri spring is the most visible due to the dam built around it, but several other springs exist along the coastline, some of which are little known locally.