Abstract:
World wide attention is given to the evaluation of performance of medium to large sized embankment da
ms, with little attention being paid to micro earthen dam. As a result the physical condition of micro eart
hen dams is generally poor, making them susceptible to failure.However, micro dams are an important s
ource of both primary and productive water for rural communities.
This research study was conducted, with the objective to evaluate seepage and slope stability performan
ces of Aguat Wuha Micro earthen dam and to come up with possible helpful remedial measures for the i
dentified safety incidents.
Aguat Wuha Micro earthen dam is located at an altitude of about 2849m asl and geographical coordina
tes of 486122.144E (UTM) &1213807.134N (UTM) in Saint ajibar Woreda south wollo Amhara region.
The AutoCAD product Geostudio-2012 software was employed to analyse the seepage using SEEP/W
and slope stability safety factors using SLOPE/W under different cases of operations.
Seepage analysis such as flow rate, pore water distribution and location of phreatic line was determine
d using the SEEP/W. Comparing the simulated result of the average flow rate of leakage for the entire le
ngth of the dam at full reservoir condition and the actually measured quantity of seepage accumulated a
t downstream toe of the dam.
From the results the measured seepage 0.00038m3/s analytically which is by timed bucket concrete
structure is greater than the simulated seepage value using software at both reservoir water level condit
ions that is at elevation of 2874 amsl & 2862 amsl i.e 0.000016499m3/s and 0.0000108397m3/s
respectively. This shows that there is an excessive seepage through the dam body which may lead to
seepage failure.
Slope stability analysis was performed for the critical slopes using the limit equilibrium SLOPE/W soft
ware based on the Ordinary, Bishop, Janbu, MorgensternPrice and Spencer methods. The stability anal
ysis results indicated that the critical upstream and downstream slope of the dam is safe within the
prescribed USACE (2003), USBR (2011) and BDS (1994) rang of factors of safety.
Key words:-Aguat Wuha Micro-earthen dam, Seepage, SEEP/W software, slope stability, SLOPE/W,
South Wollo, Amhara, Ethiopia.