( ( ( The area ) ( of ( land ( that ( ( contributes water ) ( to ( ( a ( river ( network upstream ) ) ) ( of ( ( a ( given point ) ) ( on ( a river ) ) ) ) ) ) ) ) ) ) ) ( ( is ( ( called ( ( ( ( ( ( the ( drainage basin ) ) , ) or ) watershed ) , ) ( of ( the river ) ) ) ) ( at ( that point ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN area)) (PP (IN of) (NP (NP (NN land)) (SBAR (WHNP (WDT that)) (S (VP (VBZ contributes) (NP (NN water)) (PP (TO to) (NP (NP (DT a) (NN river) (NN network) (NN upstream)) (PP (IN of) (NP (NP (DT a) (VBN given) (NN point)) (PP (IN on) (NP (DT a) (NN river))))))))))))) (VP (VBZ is) (VP (VBN called) (NP (NP (NP (DT the) (JJ drainage) (NN basin)) (, ,) (CC or) (NP (NN watershed)) (, ,)) (PP (IN of) (NP (DT the) (NN river)))) (PP (IN at) (NP (DT that) (NN point))))) (. .)))
The area of land that contributes water to a river network upstream of a given point on a river is called the drainage basin, or watershed, of the river at that point.
(ROOT (S (NP (NP (DT All)) (PP (IN of) (NP (NP (DT the) (NN land)) (VP (VBN drained) (PP (IN by) (NP (DT a) (NN river) (NN system))))))) (VP (VBZ is) (VP (VBN called) (NP (NP (PRP$ its) (NN basin)) (, ,) (CC or) (NP (DT the) (`` ``) (JJ wet) ('' '') (NN term) (NN watershed)))))))