RC14 - Above Huancaya

Site Code: RC14. GPS: S12°20043, W75°79727. Elevation: 3598m asl.

Water Quality Data

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

RC14 November 2019 November 2021
Season: Austral Summer Austral Summer
Date: 22.11.2019 19.11.21
Time: 8.00am 11.15
Width (m) 23.0 18.2
Depth (Av.) (m) 0.63 0.40
CSA (Av.) (m²) 14.42 7.46
Velocity (Av.) (m/s) 0.80 0.93
Discharge (Av.) (m³/s) 11.522 8.163
Riverbed sediment Gravel, cobbles & boulders Cobbles & Boulders
Temp. (Atmospheric) (°C) 8 16
Temp. (Water) (°C) 11.42 12.96
Atmospheric pressure (mbar) 690  
Dissolved oxygen (mg/l) 3.60 5.66
Dissolved oxygen (%) 56.3 81.4
pH 8.60 8.37
Conductivity (µS/cm) 384 477
Total Dissolved Solids (ppm) 190 238
ORP (mV) 101.9 129.6
Turbidity Clear: Clear:
Alkalinity (mg/l CaCO₃) - 144 (1.6N)
Alkalinity Field Tester (ppm/ CaCO₃) - -

Data Analysis

Discharge at this point along the Rio Canete is as expected at over 11 m3/s. Discharge rapidly falls to base flow in the latter part of the dry season and the water appears very clear.

At almost 3600m asl the DO readings at RC14 are as expected. It again follows the pattern in which DO readings slowly fall as elevation increases. The measurements for conductivity and total solids are fairly high, which probably reflects local geological conditions and weathering processes in the river channel, but this is to be confirmed. At these levels of conductivity and total solids water quality is not poor. As the population density above Huancaya is very low the impact of anthropic activity would seem to be minimal. There is little agriculture, no mining and only the village of Tanta is of any size.

Site description

Site RC14 lies in the arid temperate zone just above the town of Huancaya at 3596m asl. At this point the valley has a sharply v-shaped profile. The channel gradient is broken by a series of lakes and marshy areas forming a series of terraced weir-like landforms of natural origin. The bed load in the river channel consists of sands, gravels, and smaller boulders. The river flow in the Rio Canete is high year-round with discharge at this time perhaps approaching base flow. Fluctuations in river flow throughout the catchment may be reduced by the presence of so many lakes at this location.

There remains much agricultural activity on the south facing slope above the town, the principal crops being potatoes and quinua and alfalfa. Otherwise, extensive pastoralism dominates rural land use. There are also some relictual areas of terracing on steeper slopes. The valley here lies within the Reserva Paisajistica Nor Yauyos-Cochas and the riverine features are an important part of the reason for so designating this catchment.

Above Huancaya, the road to Tanta is also the principal transport route to San Mateo and the central highway but is little used and serves only sparse rural communities.

RC14 View upstream Site RC14 - Study site location: above Huancaya on one of the main channels above the colonial bridge. (John Forrest)

Site RC14 - the study site. (John Forrest) Site RC14 - the study site. (John Forrest)

RC14 View upstream Site RC14 - View upstream. (John Forrest)

image Site RC14 - View downstream. (John Forrest)