Inventory and geomorphological analysis of karstic collapse dolines in Sahel-Doukkala (Morocco)

In this study, an inventory of 58 karst collapse dolines within the Sahel-Doukkala, region of Morocco, was conducted from 2018 to 2020. The inventoried data include geological and geomorphological information. Data acquisition methods involved aerial and satellite imagery and field surveys. The karst collapse dolines exhibit distinct features delineating two zones with differing collapse mechanisms. In the Doukkala plain, the formation of collapse dolines is primarily driven by fluctuating water table levels influenced by annual rainfall variations. This impacts underground voids and hydrostatic stability, particularly during seasonal wet-dry cycles. In contrast, collapse dolines in the Sahel zone result from intense rainfall and rapid erosion, enlarging underground voids and triggering collapse phenomena. The analysis of their distribution related to tectonic lineaments shows two main directions: one N-S along the Sahel, corresponding to the region’s fault lines, and another NE-SW in the Doukkala plain, influenced by faults controlling surface flows. This research contributes to understanding the dynamics of karst collapses and aids in developing better management and mitigation strategies for regions prone to such geological hazards.