( ( ( Precipitation ( , ( runoff ( , ( and groundwater ) ) ) ) ) flow ) . )
(ROOT (NP (NP (NN Precipitation) (, ,) (NN runoff) (, ,) (CC and) (NN groundwater)) (NP (NN flow)) (. .)))
Precipitation, runoff, and groundwater flow.
(ROOT (S (NP (NNP Groundwater)) (ADVP (RB primarily)) (VP (VBZ comes) (PP (IN from) (NP (NN precipitation)))) (. .)))