Final answer:
A torrent of water in a desert's dry streambed resulting from a precipitation event is called a flash flood, and the dry streambed itself is known as an arroyo or wadi.
Step-by-step explanation:
If precipitation events occur in a desert, a dry streambed can fill with a torrent called a flash flood, and the dry streambed is known as an arroyo or wadi. Flash floods are sudden and can be extremely dangerous, often occurring with little warning in desert areas due to intense rainfall over a short period. An arroyo or wadi is a dry creek or streambed that temporarily or seasonally fills and flows after sufficient rain.
Deserts, known for their dry ecosystems and very little rainfall, can still experience these dramatic shifts. Runoff from rain, which is not absorbed by the soil, collects in these streambeds resulting in rapid and powerful water flow. Although the desert is primarily dry, such events can lead to significant changes in the landscape and must be respected for their potential hazard.