A Century of Riverbank Protection and River Training in Bangladesh

Abstract

Protecting against riverbank erosion along the world’s largest rivers is challenging. The Bangladesh Delta, bisected by the Brahmaputra River (also called the Jamuna River), is rife with complexity. Here, an emerging middle-income country with the world’s highest population density coexists with the world’s most unpredictable and largest braided, sand-bed river. Bangladesh has struggled over decades to protect against the onslaught of a continuously widening river corridor. Many of the principles implemented successfully in other parts of the world failed in Bangladesh. To this end, Bangladesh embarked on intensive knowledge-based developments and piloted new technologies. After two decades, successful, sustainable, low-cost riverbank protection technology was developed, suitable for the challenging river conditions. It was necessary to accept that no construction is permanent in this morphologically dynamic environment. What was initially born out of fund shortages became a cost-effective, systematic and adaptive approach to riverbank protection using improved knowledge, new materials, and new techniques, in the form of geobag revetments. This article provides an overview of the challenges faced when attempting to stabilize the riverbanks of the mighty rivers of Bangladesh. An overview of the construction of the major bridge crossings as well as riverbank protection schemes is detailed. Finally, a summary of lessons learned concludes the impressive progress made.

Studies on River Training

“…These guide banks or Bell's bunds are longitudinal guiding structures that consist of an upstream curved head, a straight shank, and a downstream curved head [6,8,12,13]. Oberhagemann [3] describes in detail the subsequent developments in training the Ganges, Brahmaputra-Jamuna and Padma rivers over the last century. Van der Wal [1] complements this with additional historical information.…”

“…Integration over the cross-section gives the total sediment load Q s = Bq s . Substitution of the relation for u 3 gives Q s = B 1−b/3 mC 2b/3 Q b/3 i b/3 . As morphological equilibrium implies that the sediment load in the narrowed reach must be equal to the sediment load in the original unmodified reach, the ratio of new slope, i 1 , to original slope, i 0 , can then be related to the ratio of new width, B 1 , to original width, B 0 , by i 1 /i 0 = (B 1 /B 0 ) 1−3/b [7] (Figure 5/2.28 in [7]).…”

“…The original invitation to authors focused on four specific areas. The first area regards the functioning of innovative river training structures, such as permeable groynes [1], submerged vanes [2] and geobag revetments [3]. The second area relates to the adverse effects of river training, often only becoming apparent and creating full awareness of their existence in the long term [4].…”

“…The third focus area concerns the advanced theory and modeling of hydrodynamics and morphodynamics to predict effectiveness and assess the impacts of river training [5]. The fourth area focuses on case studies to evaluate the long-term performance and sustainability of river training projects implemented in the past [1][2][3][4].…”

“…Havinga [4] discusses past and future training and management of the Dutch Rhine branches. Oberhagemann et al [3] describe the development of riverbank protection technology for the Brahmaputra-Jamuna River in Bangladesh. Van der Wal [1] describes his experiences with bank protection structures along the same river, focusing on ways to reduce the risk of damage by flow slides.…”