rocks and trees in dried up okonjou riverbed

africa african arid aridity boulder boulders desert deserts desiccated desiccating dried drought dry drying dryness ecosystem ecosystems format horizontal landscape landscapes lost namibia namibian natural nature okonjou omaruru parched penurious penuriousness river riverbed riverbeds rivers rivier rock rocks running scant scantiness southern southwest stone stones stream trees vegetational water zone zones