There are various methods to deal with areas such as this, and herbicides are one option. The link will explain some of these options and materials. And super strong herbicides may not be the best choice if you are looking to replant a landscape as you describe. Using a more benign material such as a glyphosate based herbicide will take more time than many more harsh materials, but it will leave the soil useful for planting and may have less non-taret effects since it won't affect the roots of desirable plants in the area. It can also be a better choice when there are concerns about wildlife in the area. That is why these products are used in invasive plant removal and habitat restoration in wild areas. Timing of the removal can be more of a consideration than anything else. You don't want to remove large amounts of cover when bird nests are active, for example.

Drain clearing materials are usually much more harsh than these.

Here is a link that might be useful: TNC Invasive species reference