The Hydraulic State by Ortloff Charles R.;

Author:Ortloff, Charles R.;
Language: eng
Format: epub
Publisher: Taylor & Francis Group
Published: 2020-07-16T00:00:00+00:00

Tiwanaku hydraulic analysis

To demonstrate the drainage channel’s hydrologic functions, multiple data assemblages used to construct a Computational Fluid Dynamics (CFD) hydrological model (Figure 5.5) include results of archaeological mapping and excavation (Kolata 1993, 2003; Janusek 2003, 2004, 2008; Janusek and Earnest 2009; Couture 2002; Couture and Sampeck 2003), Google Earth imagery and the 1930s aerial photos taken over the site of Tiwanaku. These aerial photos reveal the site decades before modern urbanization and monument reconstruction began and were taken at a time of year when many features held water thus providing a clear view of Tiwanaku’s hydrological features. From these photographs, the outline of the drainage channel is shown in Figure 5.1 as the dark encircling boundary to the ceremonial center. The curvature of the drainage canal V-D-W-X shown in Figure 5.5 is derived from earlier observations (Figure 5.18) of the canal (Bandelier 1911; Bennett 1934; Posnansky 1945; Doig 1973:352) made before years of erosion and soil deposition infilling that continues to the present day.

The east drainage canal arm (denoted Moat: east arm, Figure 5.1) averages 5–6 m deep and ranges 18–28 m in top width. Subterranean canals originating from the drainage channel’s south arm were drainage conduits for Tiwanaku’s monumental and elite residential structures (Couture and Sampeck 2003). Since the south arm of the drainage channel is shallower in depth than the north arm as determined by ground contour measurements (Kolata 2003), a fraction of the water that accumulated in this arm flowed down-slope through the drainage channel’s east and west arms toward the Tiwanaku River while a portion of accumulated water in the south arm flowed into the dual subterranean channels (Figures 5.4 and 5.5) underlying the ceremonial center region. Given the two degree declination slope of the subterranean channels toward the north, water accumulating in the drainage channel’s bottom during the wet and dry seasons provided flush water cleaning for the Putuni palace’s waste removal/drainage facilities. The north canal section (Figures 5.1 and 5.5) is vital for understanding an additional feature of the drainage channel’s hydrological function. North of Tiwanaku’s northwest monumental complex, the shallow alluvial plain drops sharply downward toward the Tiwanaku River’s marshy floodplain. One portion of the east arm of the canal turns west and disappears into the floodplain (Figure 5.1, C’) while canal (C) continues north toward the Tiwanaku River. One portion of the west drainage channel arm led into the marsh north of the Kalasasaya (Figures 5.2 and 5.5) while an ancillary arm continued northeast toward the river. The north portion of the drainage channel thus divided into several branch canals that intersected the floodplain and drained accumulated water from the north arm of the drainage channel. Water not directly shunted to the Tiwanaku River through canal C (Figures 5.1 and 5.5) drained water in the floodplain’s aquifer that directed seepage into the Tiwanaku River. The floodplain area thus served as a productive agricultural system for the urban center by utilizing its available water surplus.

Figure 5.4 Photo and plan view of the excavated portion of the subterranean Putuni channel P.

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