Site Investigation For Construction Of Emergency Spillway At The Jatigede Dam

Abstract

An emergency spillway has been planned to be constructed at the Jatigede Dam, West Java, to allow floodwater to flow downstream and to prevent the capacity of the main spillway to be exceeded during large flood events. The complex geology of the
Jatigede Dam area, however, poses a challenge to determine the suitable location for the emergency spillway construction, either in the area to the west or to the east of the embankment dam. An engineering geological mapping and landslide susceptibility
zoning were conducted to determine the engineering
geological characteristics of the area surrounding the
Jatigede Dam. The site investigation showed that the
area to the west of the embankment dam tended to
have a lower slope inclination than the area to the
east of the embankment dam. Both areas to the west
and to the east of the embankment dam were found to
be composed of less erosion resistant rock units. The
existence of the earth retaining structures for slope
stabilization in the area to the east of the embankment dam will, however, likely limit the flexibility in developing the emergency spillway route. With respect to the existence of fault systems, both areas to the west and to the east of the embankment dam will likely be influenced by similar conditions. The area
to the west of the embankment dam tended to be less
susceptible to landslide as compared to the area to
the east of the embankment dam. The undeveloped
land use of the area to the west of the embankmen dam as compared to the area to the east of the embankment dam will provide more flexibility in construction of the emergency spillway. Due to the morefavorable engineering geological conditions, the area to the west of the embankment dam is proposed for
the location of the emergency spillway construction.
Keywords: Emergency spillway, Engineering geological mapping, Jatigede Dam