( ( On ( a slope ) ) ( this ( ( can ( be ( done ( by ( ( ( ( digging ( a trench ) ) ( from ( the spring ) ) ) and ) ( ( allowing ( the water ) ) ( to flow ) ) ) ) ) ) ) . ) ) )
(ROOT (S (PP (IN On) (NP (DT a) (NN slope))) (NP (DT this)) (VP (MD can) (VP (VB be) (VP (VBN done) (PP (IN by) (S (VP (VP (VBG digging) (NP (DT a) (NN trench)) (PP (IN from) (NP (DT the) (NN spring)))) (CC and) (VP (VBG allowing) (NP (DT the) (NN water)) (PP (TO to) (NP (NN flow)))))))))) (. .)))
On a slope this can be done by digging a trench from the spring and allowing the water to flow.
(ROOT (S (NP (NNP Dig) (NNP a)) (ADVP (RB well)) (VP (VBZ allows) (S (NP (NNS people)) (VP (TO to) (VP (VB access) (NP (NN water)) (PP (IN in) (NP (NP (DT an) (NN aquifer)) (SBAR (WHNP (WDT that)) (S (VP (VBZ does) (RB not) (VP (VB flow) (PP (IN from) (NP (NP (DT a) (NN spring)) (CC or) (NP (DT a) (NN geyser)))))))))))))) (. .)))