Ouadi Rimé-Ouadi Achim Faunal Reserve is a nature reserve for animals located in central Chad. The reserve consists of three natural habitats, which are the Sahelian wooded grassland, predominantly sub-desert grasslands, in addition to the desert lands, and it is considered one of the largest reserves in the world.
Rainfall, in addition to streams flowing from the rocky massifs east of the reserve and across its floodplains, have contributed to the creation of a large biodiversity, where the vegetation mainly consists of acacia forests, Balanites aegyptiaca, Acacia tortilis, and Capparaceae plants. As for the animal species that are seen in the reserve, there are the Dama gazelle, Dorcas gazelle, red-fronted gazelle, Northeast African cheetah and addax.
The reserve was the last habitat for the Scimitar oryx before it was declared extinct from the wild.