Drainage Rearrangement as a Driver of Geomorphological Evolution During the Upper Pleistocene in a Small Tropical Basin

The development of river networks in contexts where intense tectonic activity converges with great lithological variability, such as the Ocoa River Basin in the south of the Dominican Republic, usually hosts excellent examples of drainage rearrangement. This mechanism is defined as a transfer of part or all of a river’s flow to another river. According to the process involved, drainage rearrangement may be classified in one of four categories- stream capture, river diversion, beheading and, more recently, karst piracy. The Parra River Basin (29.5 square kilometers), part of the Ocoa River Basin, features excellent examples of drainage rearrangement. The aim of this research was to detect and characterize drainage rearrangement evidence in three sub-basins of the Parra River Basin. Several geomorphological features, including striking differences in lithological types of alluvial deposits between terraces and stream beds, a sinkhole in a tributary stream, as well as high variability in basin morphometry computed using GIS techniques, suggest the development of karst piracy during the Upper Pleistocene in the Parra drainage network, along with other minor rearrangement forms. Karst piracy is an understudied model of drainage rearrangement worldwide, and so it is in the Dominican Republic. Hence, this paper contributes to a better understanding of the interaction between rivers and karst systems, at the same time providing new evidence for this little-known phenomenon.