In Israel, the term "Wadi" (borrowed from Arabic) refers to a valley, ravine, or dry riverbed that remains arid except during the rainy season. In Hebrew, the equivalent term is "Nahal." These geographical features are prevalent throughout Israel's desert and semi-arid regions, such as the Negev and the Judean Desert. During the dry summer months, a wadi appears as a rocky or sandy path through the landscape, but during the winter rains, they can transform almost instantly into powerful, life-threatening flash floods. This phenomenon is a significant concern for hikers, as rain falling miles away in the mountains can send a wall of water down a dry wadi without warning. Historically and biblically, wadis were essential for survival, as they often contained hidden springs or "water holes" where ancient travelers could find water. Today, many of Israel's most famous hiking trails, such as Wadi Qelt or Wadi Arugot, follow these natural channels, offering a unique landscape where lush vegetation can often be found tucked away in the shadows of the steep, desert canyon walls.