iss009e18679

ISS009-E-18679 (17 August 2004) --- Ural River Delta, Kazakhstan is featured in this image photographed by an Expedition 9 crewmember on the International Space Station (ISS). The Ural River is one of two major rivers (the other river is the Volga) that empty into the northern coast of the Caspian Sea, creating extensive wetlands. This image shows details of the Ural's tree-like (or “digitate”) delta. According to NASA scientists studying the Space Station imagery, this type of delta forms when wave action is low and sediment content in the river is high. New distributary channels form in the delta when the river breaches natural levees formed by sediment deposition. The dark regions running along the coast are the wetlands that support high biodiversity due to the unique environment and relative isolation of the Caspian Sea. The coastal wetlands are especially important to migrating birds as an important stop-over along the Asian flyway. The Ural River's trek to the Caspian is long — roughly 2400 kilometers (1500 miles) from the Ural Mountains in Russia south to empty into the northern Caspian Sea in Kazakhstan. Although the current sea level of the Caspian is more than 26 meters below global mean sea level the water levels have risen roughly 2 meters since 1980. This has lead to flooding of much of the coastal region, including the Ural delta, and endangers these coastal wetland environments. The coastal flooding has also impacted the oil exploration infrastructure bordering the Caspian coastline, scientists report.