Ambitious and perhaps risky business :)
What kind of soil? How much rainfall annually? 100 yr flood looks like? Overflow options for flood event?
Ive seen pics of indigenous projects on steep
land like you sketched.ive also heard horror stories of landslides, etc.
Planting shrubs might be another way to at least get water into the subsoil.
Another consideration is gutter flow from house to cistern where you could store water for irrigation, drinking, etc