Looking for advice on which kind of tree would help hold soil of creekbank. My house is just 4 M from creekbank and the depth to the lowest water level in the dry is approx 3 M. I want a deep root tree that will not spread out too much. My nearest 4 in. water-out pipe is just a meter away from planting spot. So I need a deep taproot species rather than a wide-spread root tree.

We planted paduak (Burma Padauk, Narra, Angsana Norra, Malay Padauk, Burmese Rosewood, Andaman Redwood, Amboyna Wood, Indian rosewood) between clumps of bamboo already in place but being undercut by the water. They make a beautiful tree and are doing very well. Try to get the smooth bark trees as they keep their foliage year round it seems.

Steve, I think your expectations on tree rooting may need some adjustment. You may not find a tree with only tap root formation, especially that close to a surface water source. Most tree species have lateral and oblique roots that provide absorption of water and nutrients as well as anchorage. Some arid zone natives develop tap roots in addition to later and oblique roots. You won't find a tree with only a tap root.

Tap roots develop in some tree species due to conditions where water is only available from a deeper source. When there is surface water available, most trees will take advantage of that with lateral roots.

If your water pipe is that close, then you may not be able to plant any large growing tree in that location without some possibility of structural displacement as the tree grows and expands in girth of tree trunk and root crown, and lateral roots undermine and lift.

You may find that a combination of smaller growing trees and shrubs and ground covers will work the best for soil stabilization, without risking displacement of the pipe.