Tigris–Euphrates river system border. Since the 1960s and in the 1970s, when Turkey began the GAP project in earnest, water disputes have regularly occurred in addition to the associated dam's effects on the environment. In addition, Syrian and Iranian dam construction has also contributed to political tension within the basin, particularly during drought. The general climate of the region is subtropical, hot and arid. At the northern end of the Persian Gulf is the vast floodplain of the Euphrates, Tigris, and Karun Rivers, featuring huge permanent lakes, marshes, and forest. The aquatic vegetation includes reeds, rushes, and papyrus, which support numerous species. Areas
Santa Ana River in recorded history. The levees along the river burst in many places, flooding part of the Inland Empire into a continuous body of water several miles wide stretching from the mouth of Santa Ana Canyon to where the river cuts through the Santa Ana Mountains. Downstream in Orange County, the river overwhelmed nearly all the existing floodworks and transformed the coastal plain into a transient inland sea. The flow, now calculated as a 1,000-year flood, peaked at roughly , over half the average flow of the Mississippi River. Even after the flood, detrimental conditions continued in the region. For the