Saudi Arabia does not have any permanent rivers, but it has numerous wadis (valleys), which are riverbeds that are usually dry and only flow after rainfall. Some wadis flow year-round due to the discharge of treated water from wastewater treatment plants. The longest wadi in the country, which is also the longest in the Arabian Peninsula, is Wadi Ar-Rummah, which runs through multiple provinces.
The following list of wadis is categorized by historical regions of Saudi Arabia.