A wadi is a stream or river that flows only during certain times of the year in the dry and semi-dry regions of the Middle East. These streambeds are usually dry, but they can become filled with rushing water during spring when snow melts or after heavy rains fall.
The most important wadi in the Bible was the Wadi of Egypt (also called the “Brook of Egypt” in modern Bible versions). This wadi marked the southwestern border of Canaan according to the instructions God gave to Moses (Numbers 34:5; Joshua 15:4, 47; 1 Kings 8:65; Isaiah 27:12). During dry seasons when there was no water flowing, wadis were useful as paths for travel.