Hydrometeorology of the Dhofar cloud forest and its implications for groundwater recharge

Study region: The Dhofar mountains are located on the Arabian Peninsula in Southern Oman. Unlike other regions of Oman, the Dhofar mountains have an annual monsoon season that results in a semi-arid cloud forest. The region highly depends on groundwater resources and the Dhofar mountain range is the major recharge area for the Salalah coastal plain. Study focus: Forests in cloud-impacted areas can harvest cloud-water droplets in addition to receiving rainfall. The forest interception and recharge relevant net precipitation are investigated by ecohydrological studies. These studies are, however, limited to the point or experimental plot scale and to particular tree species. Groundwater studies, in contrast, are often linked to catchment or groundwater aquifer boundaries and are therefore calculated at meso- to regional scale. To be able to utilize findings from ecohydrological site studies for regional groundwater studies we regionalize field site studies through cloud forest distribution and rainfall interpolation in a semi-arid, data scarce region heavily dependent on groundwater resources. New hydrological insights for the region: Our results are a cloud forest precipitation scenario that quantifies the additional rainfall gained through cloud water harvesting by the cloud forest. In comparison to interpolated rainfall the precipitation available for recharge within the Dhofar mountains increases by 20%. Considering a recharge-precipitation ratio calculation the recharge ratios in the region are up to 24% for highly forested areas.