Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Ouaddaï Highlands is an area in east of Chad along the border with Sudan. The Ennedi Plateau and the Ouaddaï highlands in the east of Chad complete the image of a gradually sloping basin, which descends towards Lake Chad. There are also central highlands in the Guera region rising to 1,500 m (4,921 ft). Batha River is an important Ephemeral river that carries water west from these highlands during rainy seasons, usually during flash flooding. Ouaddaï highlands mark Chad's eastern border and also divide the Chad and Nile watersheds. These highland areas are part of the East Saharan montane xeric woodlands ecoregion.