Classification of karst springs for flash-flood-prone areas in western Turkey

Abstract

Flash floods are caused by heavy rainfall that has become more frequent. They are more prominent in low-storage karst regions, although karst terrain often acts as a natural flood control particularly when it is bare and dominated by conduits. A study using a hydrogeochemical approach and assessing data from several springs in different carbonate rock in western Turkey has made it possible to classify karst aquifers based on their response to heavy rainfall events. According to this aim, physico-chemical measurements in wet and dry seasons and discharge rates in springs are compared in order to explain aquifer characteristics. Groundwater samples have a pH ranging from 6.3 to 8.9, temperature (T) varying from 7 to 35 °C and electrical conductivity (EC) ranging from 140 to 998 µs cm−1. Groundwater samples with high EC, high T and low dissolved oxygen (DO) represent the deep circulating water, while low EC, low T and high DO are linked to the shallow circulating water. Lower variability between wet and dry seasons reveals that fracture permeability is predominantly controlled by diffuse groundwater flow with low or high storage, and conduit permeability with high storage. However, variability of the physico-chemical characteristics is higher in a conduit permeability with low storage. These types of aquifers with high transfer capability, predominantly controlled by turbulent groundwater flow, affect flash floods