Right
谷 supplies the sound — gǔ drifting to yù via well-attested g/y alternation in classical readings.
谷 itself depicts a stream flowing between two mountains, meaning 'valley.' Carries a faint semantic flavor: a wide valley is roomy and open, just as
裕 means 'roomy, ample, well-off.' Same phonetic in
浴 to bathe,
欲 desire.