Tigris–Euphrates river system through the central plain and combine at Al-Qurnah to form the Shatt al-Arab and discharge into the Persian Gulf. The region has historical importance as part of the Fertile Crescent region, in which civilization is believed to have first emerged. The ecoregion is characterized by two large rivers, the Tigris and Euphrates. The rivers have several small tributaries which feed into the system from shallow freshwater lakes, swamps, and marshes, all surrounded by desert. The hydrology of these vast marshes is extremely important to the ecology of the entire upper Persian Gulf. Historically, the area is known as Mesopotamia. As
Rainworth Water wetland habitats. Typical of such schemes is an area of wetland at Thieves Wood that would allow run-off from the A60 to deposit silt, and chemical contaminants to be removed before the water enters the main river. It would also create a head of water, which would be released into the river more slowly, levelling out the periods of high flow and low flow. The Environment Agency are responsible for measuring water quality of the river systems in England. Each is given an overall ecological status, which may be one of five levels: high, good, moderate, poor and bad. There