Complex sentence: The Mareb is dry for much of the year, but like the Takazze is subject to sudden floods during the rainy season; only the left bank of the upper course of the Mareb is in Ethiopian territory.
Split into simpler sentences: The Mareb is dry for much of the year, but like the Takazze is subject to sudden floods during the rainy season. Only the left bank of the upper course of the Mareb is in Ethiopian territory.