RC16 - Tanta

Site Code: RC16. GPS: S12°07.448, W76°00.833. Elevation: 4285m asl.

Water Quality Data

The following river and water quality data was collected from this site:

RC16 November 2019 May 2021
Season: Austral Summer Austral Winter
Date: 22.11.2019  
Time: 12.00pm  
Width (m) 17  
Depth (Av.) (m) 0.063  
CSA (Av.) (m²) 1.071  
Velocity (Av.) (m/s) 0.105  
Discharge (Av.) (m³/s) 0.112  
Riverbed sediment Pebbles \& boulders  
Temp. (Atmospheric) (°C) 9  
Temp. (Water) (°C) 8.5  
Atmospheric pressure (mbar) 659  
Dissolved oxygen (mg/l) 3.1  
Dissolved oxygen (\%) 52.07  
pH 8.44  
Conductivity (µS/cm) 132  
Total Dissolved Solids (ppm) 66  
ORP (mV) 136.7  
Turbidity Clear:  
Alkalinity (mg/l CaCO$_{3$) Pink to colourless 168 (1.6N)  

Data Analysis

Discharge for the Rio Cañete at this point is constant as it is fed by a series of bofedales lying beneath the remaining snowfields above.

At over 4200m asl the DO readings at RC16 fall within the range to be expected. It again follows the pattern in which DO readings slowly fall as elevation increases. The measurements for conductivity and total solids are now low, reflecting the fact that channel flow is derived from bofedales where it has been filtered. As there is only a low population density above this point in the headwaters anthropic impact is low. There is some pastoral agriculture associated with the town of Tanta, which is more intensive close to the town.

Site RC16 - satellite image of Tanta village - the study site is located below the bofedal, just above the village. (Eustace Barnes) Site RC16 - satellite image of Tanta village - the study site is located below the bofedal, just above the village. (Eustace Barnes)

Site RC16 - the study site, view upstream. (John Forrest) Site RC16 - the study site, view upstream. (John Forrest)

image

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Site description

Site RC16 lies in the puna zone above the small town of Tanta at 4285m asl. At this point the valley has a U-shaped profile typical of glaciated landscapes and is dominated by the nearby snow-covered peaks and valley bofedales. The bed load in the river channel is comprised of fluvio-glacial boulders, gravels, and sands. The river flow in the Rio Cañete is constant and year-round.

There is no agricultural cultivation taking place at present, with pastoralism dominating any rural land use (See Fig.[fig:RC16a] and Fig.[fig:RC16b]). This area was always a transhumance focal point and would have been more densely populated during the Inca empire and earlier.

The principal anthropic impacts at this site would be overgrazing and cutting of peat from the bofedales. The latter was always a destructive process, impacting on water availability and quality as well as soil erosion and flood risk and thus is another practice best avoided.

The flora and fauna at this elevation is dominated by high elevation components and communities. In addition to those species mentioned so far, the bofedale habitats also support a highly specialised fauna. This might include Puna Tinamou, Rufous-bellied Seedsnipe, Diademed Sandpiper-Plover, White-bellied Cinclodes, Olivaceous Thornbill, Black-breasted Hillstar and Dark-winged Miner along with other Furnarids and Tyrannids. The biodiversity of these bofedales is the subject of on-going investigation.