Hydraulic Failure of Micro Embankment Dams and Remedial Measures (Case Study: Zana Med, Amhara Region)

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Addis Ababa University


The main intention of this study is identifying the causes of hydraulic failure of Zana Micro- Embankment dam with emphasize on seepage. The selected area is found in Amhara National regional state, North Gonder zone, East Belesa woreda. The dam is located on Zana River, tributary of the Tekeze River. Even though the study area has been selected based on the available data as compared with the other problem area, to attain the primary objective of the research the available data is so limited. The work has delt with a unidirectional investigation. Seepage analysis and filter media design of the dam which has been stated in the design document were thoroughly investigated. Darcy’s law-phreatic line, flow Net and SEEP/W software model are used to analyze the quantity of seepage through homogeneous and zoned dam, without the provision of filter material. The flow net diagram is drawn with help of AutoCAD soft ware aided by free hand sketching for both cases. The expected quantity of seepage estimated with these different methods relatively resembles each other. The maximum seepage through the dam as per the SEEP/W software model analysis that includes foundation seepage is 7.06*10-3 cm3/sec. This value is compared with the quantity of seepage estimated at the designed document that is 7.31*10-2cm3/sec. Therefore, the design document has no problem of quantifying the expected quantity of seepage. However, the drainage system is not properly designed at the design document. To this end, failurity of seepage at the d/s face of the dam which are threatening the dam stability are expected to result from improper filter media design. Even though, the dam has a problem data on construction history, this study analyze with the help of field investigation, the cause of seepage failurity at side of spillway due to poor construction quality. To alleviate the problem grouting, impervious blanketing and d/s berming are the proposed remedial measures for seepage and leakage failures.



Amhara National regional state, North Gonder zone, East Belesa woreda