Complex sentence: The River Litani and the River Jordan are the only rivers of any size; perennial brooks are very scarce and the wadis, while numerous and impetuous in the rainy season, are dry during the rest of the year.
Split into simpler sentences: The River Litani and the River Jordan are the only rivers of any size. Perennial brooks are very scarce and the wadis, while numerous and impetuous in the rainy season, are dry during the rest of the year.