Establishment of Groundwater Level Warning for Covered Karst Areas in Northern China

In view of the resources shortage and geological environment problems caused by over-exploitation of groundwater in northern China, the delineation of the groundwater level warning (GLW) is urgently needed. Based on the comprehensive consideration of the management objectives of water resources supply guarantee and karst collapse hazards warning, this paper proposed a method for the delineation of karst GLW in covered karst areas. Specific steps include: (1) establish the criterion of GLW based on statistical analysis of groundwater level using the groundwater depth criterion model of Pennsylvania as a reference; (2) establish the criterion of GLW for karst collapse in line with the experience and mechanism research; (3) establish the comprehensive judgment criterion model to determine the GLW of a single observation well; and (4) determine the GLW divisions based on observation wells cluster and issue and renew the warning afterward. The method was verified in the Chengqu-Jiuxian Karst System (CJKS) of Taian City in Shandong Province. It is demonstrated that the GLW conducted by the method in the study area was reasonable and reliable, and was appropriate for decision making for water authorities and governments.