Ecohydrology & sustainable sediment management in inland water bodies in Ethiopia: A review with a case study site at Lake Tana in the Blue Nile (Abbay) Basin.

The paper forms part of an UNESCO-IHP’s FRIEND/ Nile-phase II Project with an overall aim of using ecohydrology as an important tool for integrated water resource management, IWRM in improving the sustainability of freshwater resources in the Nile basin. With a case study site at Lake Tana in Northwestern Ethiopia, the main objective of the study was to conduct a background preliminary review and investigate the sedimentation status of the lake and 15 reservoirs (in 6 river basins) in Ethiopia to recognize prospects and explore the possibility for sustainable sediment management in inland water bodies in the country. In an overall conclusion, the study demonstrated that several of the inland waterbodies considered here-in exhibit extremely high values of catchment sediment yield (incoming sediment loads) and sedimentation rates resulting in severe economic, social, and environmental concerns. It also revealed that most of the artificial storage facilities (reservoirs) exhibitphysical limitations hampering the use of hydrologic sediment management techniques such as flushing and sluicing. The study further implicated that sedimentation was only an aspect of the anthropogenic effects/threats to the water ecosystems, and it is usually linked up with other correlated/associated adverse ecological and hydrological effects. Besides, emerging new and /or exacerbated ecological and hydrological conditions previously unaccounted for are resulting in deterioration of quantity and quality of water, loss of ecosystem services and eutrophication of water bodies. Hence, the study verified that most of the storages facilities in the country generally require separate and /or additional complementary sediment management options to reduce their sedimentation and associated problems. As a consequence, it was deduced that ecohydrology and phytotechnology, in complement to the conventional hydro technical technologies, has the potential to address the problems of sedimentation and the associated adverse effects. Moreover, future research areas were recommended along with suggestion of some potentialphyto-technologies for trial and use in the case study area. Finally, the summary of the identified ecohydrological issues of the case study area, existing knowledge gaps, and proposals on ways to fill them were acknowledged and presented.

کلیدواژه ها:

FRIEND/Nile II ، reservoir sedimentation ، anthropogenic effects ، sediment loads ، controlling sediment yield ، ecohydrological system solutions ، knowledge gaps