The karst landscape of the Dhofar Mountains (Sultanate of Oman). Landforms and human exploitation at the edge of the Indian Ocean Monsoon

The Dhofar Mountains (southern Sultanate of Oman) are a system of Late Cretaceous to Neogene limestone strata gently rolling to the north and intersected by a system of transtensional faults, which have contributed to the uplift of the plateau and the formation of a stepped escarpment up to ~850 m asl. The massif is dissected by a dendritic system of valleys carved into the bedrock, which are active in the monsoon season (May to September) and are often blocked by massive calcareous tufa dams that have formed since the Middle Pleistocene along knickpoints of structural origin. The surface of the Dhofar Mountains is characterized by widespread rock outcrops due to intense denudation processes that, likely since the last millennia of the Holocene, have removed the superficial soils. These outcrops exhibit evidence of karst dissolution at small to medium scales, including the presence of common flat-bottomed solution dolines, often used for livestock enclosures or, due to their ability to retain soil, for rain-fed cultivation. Elsewhere, collapse sinkholes connect the plateau surface to the underground karst system, which has only been partially explored. Field surveys of the Dhofar Mountains' surface have revealed the extensive complexity of the geomorphological processes affecting the area. The evolution of the dendritic hydrographic system, consisting of deep canyons, is closely linked to the presence of faults and connected to the deep karst system, likely evolving through collapse and exhumation processes of the cave system. Evidence of this includes the presence of sinkholes at valley bends, inland notches and rock-shelters opening at different elevations along the valleys, and the identification of riverbeds showing relief inversion in association with faults and sinkholes. The karst landscape of the region has been exploited since the early Holocene and especially in recent millennia. Human activity has significantly influenced the dynamics of surface processes, together with the monsoon rains from the Indian Ocean, which are the primary agents shaping the appearance of the plateau surface.