Name a river starting from arequipa region?
SELECT DISTINCT ?uri WHERE {?uri <http://dbpedia.org/property/sourceRegion> <http://dbpedia.org/resource/Arequipa_Region>  . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/River>}
Arequipa_Region