RT09C - Upper Alis

Site Code: RT09C. GPS: S12°277975, W75°644980. Elevation: 4180m asl.

Water Quality Data

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

T9c November 2021
Season: Austral Summer
Date: 18.11.21
Time: 8.00am
Width (m) 2.05
Depth (Av.) (m) 0.07
CSA (Av.) (m²) 0.14
Velocity (Av.) (m/s) 0.16
Discharge (Av.) (m³/s) 0.023
Riverbed sediment Pebbles & Cobbles
Temp. (Atmospheric) (°C) 12
Temp. (Water) (°C) 8.08
Atmospheric pressure (mbar) (<600)
Dissolved oxygen (mg/l) 5.01
Dissolved oxygen (%) 69.05
pH 7.92
Conductivity (µS/cm) 773
Total Dissolved Solids (ppm) 387
ORP (mV) 47.2
Turbidity Clear:
Alkalinity (mg/l CaCO₃) 170
Alkalinity Field Tester (ppm/ CaCO₃) -

Data Analysis

Discharge at this point on the Rio Alis was very low suggesting that the rains had not yet started in the headwaters of this sub-catchment though the size of the channel suggested that it rarely carried much more water.

At nearly 4200m asl the DO readings at T9c were lower than at many other sites but still fall within the range to be expected for a November data set.

The conductivity reading at this site (773 µS/cm) is slightly higher than is expected for a site located above all major settlements within a sub-catchment but probably reflects local geological conditions and weathering processes in the river channel.

The pH reading of 7.92, is slightly lower compared to other sites but is as expected. At these levels the alkalinity of the river is suitable for aquatic life and indicative of clean water.

Site description

Site T9c lies in the Rio Alis valley at 4180m asl. The valley at this point is wide with a u-shaped profile and a wide flood-plain though there is little evidence of the river frequently overflowing its narrow channel. River flow in the Rio Alis is year-round and overall makes a significant input to the Rio Cañete further downstream.

Bed load in the river channel is comprised almost entirely of smaller sediment material.

There is no agricultural cultivation taking place, the banks and hillsides are lined with open pasture where cattle and alpacas graze. However, there is some evidence of more intensive land use having taken place in the past; old corrals being located nearby. Currently, there is only permanent settlement (homestead) slightly higher up the valley.

Andean goose, Andean and Puna Ibis are found feeding in the wetter soils and marshland.

Site T9C - the study site. (John Forrest) Site T09C - the study site (November 2021) (John Forrest)

Site T9C - the study site. (John Forrest) Site T09C - the view upstream (November 2021) (John Forrest)

Site T9C - the study site. (John Forrest) Site T09C - the view downstream (November 2021) (John Forrest)