Black Warrior River NEON / BLWA

The Black Warrior River site (BLWA) is an aquatic site on the Black Warrior River in west-central Alabama. The site sits in the lower extent of the river’s 16,160 km² (nearly 4 million acre) watershed, 11 km upriver from its confluence with the Tombigbee River. As a navigable river, it is managed by the U.S. Army Corps of Engineers; the property used to access BLWA is privately owned. The site is forested, and the topography is flat with shallow depressions. The river is impacted by a series of locks and dams, coal-fired steam power plants, and urban and agricultural use. BLWA is part of NEON's Ozarks Complex Domain (D08). D08 includes 2 other aquatic field sites and 3 terrestrial field sites. BLWA is colocated with the terrestrial site at Dead Lake (DELA). [1]

West-central 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 Black Warrior River basin. These events affect nutrient and organic matter flux, sediment transport, and the river’s biota. The mean average annual temperature is 17.6°C (63.7°F) and the average annual precipitation is about 1370 mm (54 in.). The area is subject to tornadoes and hurricanes annually. [1] [3] [5] [12]

The Black Warrior River has a meandering channel with geomorphological features including oxbow lakes, flood plain steps, and steam terraces. The river is located in the Southern Coastal Plain, an area bounded by an erosional scarp from the Atlantic shoreline during the Mesozoic; the region was exposed and submerged below sea level several times, leaving marine deposits of sand and carbonates as well as riverine deposits of clay, silt, sand, and gravel. At the BLWA site, there are Quartenary-aged alluvial, coastal, and terrace deposits. Upstream alluvial deposits are primarily sourced from the Cretaceous Eutaw and Tuscaloosa formations. [2] [7] [11]

BLWA is located in the Blackland Prairie or "Blackbelt," an area known for its nutrient-rich, dark soil. These soils are primarily clays and loam that weather into nutrient rich soils that can bake in the summer and become adhesive when wet. Major soil series at DELA, the colocated terrestrial NEON site, include Angie and Leaf, with lesser areas of Cahaba, Dulac, and inclusions of Annemaine. These soils are characterized by thin organic horizons, and deep (over two meters to bedrock) alluvial deposits of largely clayey sediment. The most dominant soil types are well drained and have an increase in clay content with increased depth. [2] [3]

The Black Warrior River begins at the confluence of the Locust, Mulberry, and Sipsey Forks in northern Alabama and ends at its confluence with the Tombigbee River near Demopolis, AL. The river drains from a 16,160 km² (nearly 4 million acre) watershed, or 12.2% of Alabama’s land area. The river is managed as an inland waterway with a system of locks and dams that significantly reduces the flow in the river, creating a series of lentic environments in the river, reducing lateral connectivity between the river channel and its floodplain and off-channel areas, and resulting in high discharge pulses at BLWA. The streams in the lower section of the watershed are generally glide/pool, low gradient, and habitat poor. Streams in the northern section of the lower Black Warrior watershed flow year round due to sand and gravel aquifers in the area; whereas, streams in the southern section will usually go dry or flow will become quite low. The watershed 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. [3] [6] [7] [8]

Broadleaf deciduous forest with concentrations of low needleleaf evergreen trees and patches of bluestem prairie are typical of the lower reach of the Black Warrior watershed and along riverine systems throughout the region. In the lowland, hardwood tree species dominate, including black gum (Nyssa sylvatica), sweetgum (Liquidambar spp.), elm (Ulmus spp.), ash (Fraxinus spp.), and various oak species. Upland areas feature a higher concentration of pine species. [2] [3] [8]

Some common fish species in the area include bass, bluegill, and channel catfish. Additionally, the Black Warrior basin is home to several uncommon fish species, including Cahaba shiner (Notropis cahabae), coal darter (Percina brevicauda), and Tuskaloosa darter (Etheostoma douglasi). The basin has an estimated 50 species of freshwater mussel, including nine species listed as threatened or endangered under the Endangered Species Act. NEON collects data on macroinvertebrates at BLWA. [3] [7]

The Black Warrior River has undergone significant changes in adjacent population, land use, and flow regime in the last 200 years. Perhaps the most significant is the construction of the lock and dam system, which began in 1888 and spurred the development of industry along the river. Before this, passage on the Black Warrior River by steamboats and barges was limited to high water and ended at Tuscaloosa. The river’s development into an inland waterway led to a management focus on the maintenance of a single shipping channel, which has contributed to a significant loss in lateral connectivity of the main channel to its floodplains and off-channel areas. Regional vegetation has also undergone changes in recent history. On a broad scale, upland forests once managed by Native Americans through the use of controlled burns were heavily logged for timber production and land clearing by European settlers. In terms of wetland ecology, the Black Warrior River historically featured vast canebrakes, or dense monotypic stands of giant cane (Arundinaria gigantea); while giant cane is still found near creeks, rivers, and in forests, these extensive stands no longer exist. Canebrakes served as important ecosystems, sediment traps, and a resource for Native Americans (with applications ranging from its harvest as a potherb to its use as a construction material), but were largely destroyed by livestock overgrazing after European settlement. [3] [4] [8] [9] [10]

The Black Warrior River is managed by the U.S. Army Corps of Engineers as an inland waterway with a series of six locks and dams. The river forms part of the Warrior-Tombigbee Waterway, which is heavily used for barge transportation and moves more than 25 million tons of products and materials each year. The river is also used recreationally, and popular activities include hunting, fishing, canoeing, kayaking, and boating. BLWA is located in the Major Land Resources Area 133A (the Southern Coastal Plain), where the primary land-use is timber production, followed by cropland and pastureland [7]. [1] [3]

Site characterization and initial dry-runs of observational sampling at BLWA occurred in 2016, followed by the first publication of observational data in 2017. Permitting constraints with the U.S. Army Corps of Engineers and the flow and sedimentation regimes of the river necessitated the installation of on-shore infrastructure on private land as well as an overall modified site design compared to typical aquatic sites. This included the addition of a level gauge at the site which can continuously monitor water level. Instrumentation at the site, which includes a profiling buoy and the aforementioned level gauge, went live and began streaming data in 2018. [1]