Road gutters lined with rocks?

We live in the tropics with heavy rains during the wet season. Our road is quite steep and we’ve dug a gutter next to it to allow the water to run off. The usual way to line gutters here is with half-open concrete tubes, which works really well. We however have lots of big rocks scattered around which have been dug up by the previous owner. Would that suffice to slow the water and stop the soil from eroding? And would it be beneficial to plant species that control erosion (deep roots, such as canna indica) in the gutter or better to plant them on the banks?

Any advice appreciated!