Lower Tombigbee River NEON / TOMB

The Lower Tombigbee River (TOMB) is an aquatic field site located in the Coastal Floodplains of southwest Alabama in Choctaw County. It is within the Tombigbee River Basin and is colocated with the 17 km² (4218 acre) Choctaw National Wildlife Refuge near the small town of Coffeeville, Alabama. The Lower Tombigbee River is the section of the river and watershed below where the Black Warrior River joins, and is managed by the U.S. Army Corps of Engineers. The Tombigbee watershed covers 47,0845 km² (116 million acres) and spans most of western Alabama. TOMB is located in the southern extent of the watershed, 15 km (9 mi.) upriver from the Coffeeville lock and dam. TOMB is part of NEON's Ozarks Complex Domain (D08). D08 includes two other aquatic field sites and three terrestrial field sites. TOMB is colocated with the Lenoir Landing terrestrial site (LENO). [1] [2]

Alabama has a subtropical climate with hot summers, mild winters, and year-round precipitation. Summers are hot and humid, dominated by maritime tropical air from the Gulf of Mexico and the Atlantic. This warm, moist air contributes to the formation of convection storms and thunderstorms in the region, causing major precipitation pulses in the Tombigbee River Basin. The area is subject to tornadoes and hurricanes. The mean annual temperature is 18.1°C (64.6°F) and the region averages 1386 mm (55 in.) of precipitation annually. [2] [5] [8]

The geology at TOMB is characterized by alluvial, coastal, and terrace deposits. The parent materials at the nearby colocated terrestrial site, LENO, are primarily Holocene-aged alluvial deposits, with the upstream source of the alluvium mainly Eocene-aged materials from the Wilcox and Claiborne groups. Coastal and terrace deposits are also found at LENO. [3] [11]

Soils at TOMB are in the soil subgroup Vertic Epiaquepts, which are characterized as fine, mixed, active, acid, and thermic. The major soil series on the colocated NEON site LENO include Urbo, Mooreville, and Una, with minor extents of Riverview and Mantachie on higher positions. [3]

TOMB is located within the Tombigbee River basin, which is encompassed within the Mobile River Basin. The 35656 km2 (8.8 million acre) basin straddles the border between Alabama and Mississippi. The Tombigbee River gathers the flow from four major rivers: the Buttahatchee, Noxubee, and Sucarnoochee from the west, and the Sipsey from the northeast. The main branch of the river flows from northeastern Mississippi to western Alabama, where it joins with the Black Warrior River and eventually drains into the Mobile River. The flow and transport of sediment in the Tombigbee River is generally regulated by locks and dams. The river is also impacted by coal-fired steam power plants, as well as urban and agricultural land use. The Tombigbee River Basin is subject to major precipitation pulses from tropical storms and hurricanes. These major events affect nutrient and organic matter flux, sediment transport, and biota along the gradient as they propagate downstream. [2] [14]

The vegetation around TOMB is dominated by closed-canopy pine-oak mixed forest, and also includes meadows and wetlands. Pine trees are typically found in higher, relatively less flooded areas, while oaks are distributed throughout the whole area, including the lower land with standing water. Some common species found in the canopy include a broad mix of cypress (Taxodium spp.), black gum (Nyssa sylvatica), shagbark hickory (Carya ovata), oaks, and green ash (Fraxinus pennsylvanica). Ground cover includes bamboo, grass, smilax and poison ivy (Toxicodendrom radicans). [1] [6]

The nearby Choctaw National Wildlife Refuge provides a protected wintering area for waterfowl and wood duck brood habitat. Other wildlife at the Refuge include white-tailed deer (Odocoileus virginianus), gray squirrels (Sciurus carolinensis), raccoons (Procyon lotor), opossum (Didelphis virginiana), American alligator (Alligator mississippiensis), and beaver (Castor canadensis). The Mobile River Basin is considered a biodiversity hotspot; nearly 40% of North America's aquatic turtle species can be found here (17 species), it has the third highest number of fish species in the nation (160 species), it has the highest number of aquatic snail fauna in the world (120 species), and it ranks in the top ten river basins in the world for freshwater mussel diversity (75 species). [1] [4] [14]

The Tombigbee River Basin was primarily settled by the Choctaws when European explorers and settlers arrived in the 1600s. The Choctaws and Chickasaws surrendered their claims to all territory on the eastern side of the Tombigbee in 1816 and the Choctaws later ceded their lands west of the Tombigbee in 1830. Following the 1830 Indian Removal Act, the U.S. government used forced treaties to relocate the Cherokee, Choctaw, Chickasaw, and Creek off the land. The Corps of Engineers first surveyed the river in 1870 to implement a series of locks and dams. The Coffeeville Lock and Dam in Choctaw County was completed in the early 1960s. In 1964, the Choctaw National Wildlife Refuge was established; it is bordered on the east by the Tombigbee River, which is a part of the property obtained by the U.S. Army Corps of Engineers for the Coffeeville Lock and Dam project. The refuge is still maintained today to provide habitat for breeding waterfowl. [9] [10] [13]

The Lower Tombigbee River is a navigable river managed by the U.S. Army Corps of Engineers and is subject to restrictions on use and the visibility of infrastructure. Included in the management of this river system are a series of locks and dams which severely impact flow and the transport of sediment. In addition, the river is impacted by coal-fired steam power plants, as well as urban and agricultural land use. Other major industries include chemical, pulp and paper, iron and steel, textile manufacturing, and silviculture, the largest industry in Alabama. The neighboring Choctaw National Wildlife Refuge is managed by the U.S. Fish and Wildlife Services and is used to preserve habitat for breeding waterfowl. [2] [9] [12]

NEON site characterization at TOMB was completed in 2016. AOS data products at TOMB became available in 2016, and AIS data products became available in 2018, signaling transition to full operations.