Permaculture in New Zealand

WE are just starting up a fruit forest on a hillside (steepish- but haven't had to terrrace) and being new to permaculture, we were curious to know what people thought about the importance of factoring in swales here in New Zealand- granted we are on the coast east of WHangarei and this summer has been a drought and a swale would have been valuable- but in normal circumstances (what ever they are) how important are swales?

Hope some one can enlighten us.

Cheers

Lilian