La Revista Digital 1 Versión Final Revista No. 2 - Prueva | Page 47

Water, Silt and Dams: Prehispanic Geological Storage in the Cordillera Negra, North-Central Andes, Peru
Figure 4. Plan of Cho 2 – Oleron Cocharuri.
the system still represents an important source of forage for
the herds of three local communities - Putaca, Cajabamba
Alta and Breque (Figure 6). These three villages all have
overlapping rights to the area and conflicts between them
are common. The dam stretches across the whole of a large
flat plain that extends from just above the confluence of
the Rico and Huinchos River, where it is renamed the
Chaclancayo River, to the village of Breque, located on a
southern curvature of the basin and Huinchos River. The
silt depth of the dam is over 6.5 m near the dam itself,
slowly rising to 1.2 m at a distance of 750 m from the
dam. The bofedal though extends almost to the village of
Breque, located about 3 km distant.
probable that it was refurbished or expanded during the
Inca Period (AD 1480-1532). Given the amount of time
that this basin would have required to silt up, it is possible
that for a considerable period the basin would have been
partially bofedal and partially water.
Figure 6. Aerial photograph of Co 1 - Collpacocha, showing
bofedal behind dam wall.
Photo: Instituto Geográfico Nacional, Lima).
Figure 5. Photograph of Co 1 – Collpacocha, Chaclancayo
River. Photo: K. Lane, 2002.
This silt dam is unique not only for the immense size
of its basin but also because of its close location to the
important Inca settlement of Intiaurán [Co 2] (Lane and
Contreras, 2007). While it is likely, as with the other
structures in the study area, that the dam was built during
the Late Intermediate Period (AD 1000-1480), it is also
Revista de Glaciares y Ecosistemas de Montaña 2 (2017): 41-50
Collpacocha [Co 1] is 100 m in length, oriented north
to south, cutting directly across the path of the Huinchos
River. At its widest, it is 11 m thick and is constructed of
three major stone steps, in-filled with medium and small
stones compacted with silty clay (Figure 7). Parts of the
structure, especially along the center and the southern
end, were stripped of construction stone blocks, possibly
removed by either erosion or local people. The total height
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