Streambank Soil Bioengineering Approach to Erosion Control

Rivers in tropical regions have been submitted to strong environmental impacts through changes in the hydrologic and sedimentological regime, and also to the ongoing destruction of their riparian vegetation, despite the important role of riparian vegetation in riverbank protection through root systems and plant cover, which improve soil particle aggregation in a low cohesion situation, reducing runoff and resulting in a lower erosion rate and sedimentation of the river channel. Rivers are in effect often referred to as dynamic systems which means they are in a constant state of change. Techniques of stream bank and bed stabilization are needed and can be accomplished in several ways, such as the use of rockfill, which, though efficient, is quite expensive, precluding its use extensively along the river banks. In an attempt to solve the problem, riverine populations have resorted to various empirical solutions that, in addition to not producing the desired effect, cause problems for riparian vegetation recovery besides degrading the landscape (Holanda et al., 2010). The function of riverbank protection is to avoid bank erosion, that could cause movement of the river channel, which can be of vertical and horizontal direction, arise meandering, braiding, or moving and changing the river s path. As an alternative to the empirical practices of the riverines and to expensive bordering and rockfill techniques, the use of abundant raw material has been tested and used, providing a way of mitigating the problem that can be economically viable and with proven technical efficiency. This chapter intends to discuss soil bioengineering as a biotechnology that consists of the use of living materials or inert plant substances, biotextiles, associated or not with rocks, concrete, or metals that present themselves to be environmentally sustainable to riverbank erosion control at the various conditions of slope and soil texture along their water systems like reservoirs, irrigation canals, and rivers. Soil bioengineering can be applied in the mitigation of watershed disasters and protection and restoration of ecology. In soil bioengineering, plants assume an important ecological contribution (providing multiple ecological services), as well as an economic, and especially structural, contribution in contrast to other technologies in which plants are merely an aesthetic component of design. Also, a discussion will be developed on the vegetation component, which has a great importance in these biotechnologies, recognized not only for its landscaping qualities, but also for its beneficial hydromechanical effects and protection against soil erosion.