Also it flows through forested sandy country adaptable to the conservation of runoff and is fed by many flowing tributaries and springs. It has, therefore, a remarkably strong flow for its length, and it discharges the largest volume of water at its mouth of all Texas rivers. Toledo Bend Reservoir, qv on the Texas and Louisiana border. The Sabine River basin is characterized by flat slopes and wide, timbered floodplains. High rainfall rates produce frequent flooding of low-lying areas, and large floods occur, on the average, every five years.
Floods generally rise and fall slowly, although flash floods occasionally occur in the basin.
During flood the lowest part of the basin usually remains inundated for many days, and sometimes for several weeks. The extreme southern portion of the river is subject to hurricane flooding. In its upper reaches the river traverses rolling terrain with soils of deep sandy loams, loamy sands, and sand. Loblolly, longleaf, and shortleaf pine, post, southern, red and white oak, and flowering dogwoods grow throughout the region. Cottonwood, cypress, hackberry, pecan, blackgum, hickory, and blackjack oak are scattered throughout the area.