What is the {river} for {mouth of the watercourse} of {Hertfordshire}
Name the river that is located in Hertforshire?
What river is in Hertforshire?
SELECT DISTINCT ?u WHERE { ?u property:mouth_of_the_watercourse resource:Hertfordshire . ?u rdf:type ontology:river }
select distinct ?subj where { ?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> ?subj . ?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P403> . ?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q3410> . ?subj <http://www.wikidata.org/entity/P31> <http://wikidata.dbpedia.org/resource/Q4022> } 
 select distinct ?sbj where { ?sbj wdt:P403 wd:Q3410 . ?sbj wdt:P31 wd:Q4022 } 
River Ash