Specifically for wastelands that border canals, rivers or other large bodies of water. Dredging raises questions concerning the ownership of objects found on the riverbed as much as the riverbed itself. Reclaiming kipple or waste in this way also invites speculation among the dredging party - what do we expect or desire to find in the murky depths of these submerged territories?
Industry & Dredging
On an industrial scale the process of removing trash and debris would often be combined with Maintenance Dredging in preparation for the deepening or maintenance of navigable waterways. These large scale operations are often highly disruptive to aquatic ecosystems and continue daily in order to permit international trade that relies on the reclamation of shipping routes from sedimented sand and mud.
The ancient method of panning could also be employed to retrieve physical material from the water bed by first using small scale devices to extract sediment. These techniques could also be developed for dry land exploration.