RT09A1 - Lower Alis

Site Code: RT09A1. GPS: S12°28671, W75°787584. Elevation: 3254m asl.

Water Quality Data

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

RT09A1 July 2019 November 2019 November 2021 March 2022 June 2022
Season: Austral Winter Austral Summer Austral Summer Austral Summer Austral Winter
Date: 11.07.2019 21.11.2019 15.11.21 28.3.2022 29.6.22
Time: 16.30 15.45 12.30 9.45 9.00
Width (m) 8.0 6.0 7.5 10.7 9.2
Depth (Av.) (m) 0.64 0.90 0.63 0.82 0.82
CSA (Av.) (m²) 5.09 5.40 4.73 5.44 7.54
Velocity (Av.) (m/s) 1.17 0.68 0.73 1.08 0.94
Discharge (Av.) (m³/s) 5.958 3.661 3.45 5.875 7.09
Riverbed sediment Cobbles & Boulders Cobbles & Boulders Cobbles & Boulders Cobbles & Pebbles Cobbles & Pebbles
Temp. (Atmospheric) (°C) 16 24 19 15 10.5
Temp. (Water) (°C) 11.24 12.69 12.22 11.36 10.90
Atmospheric pressure (mbar) 599 680   702 <600
Dissolved oxygen (mg/l) 5.04 3.63 6.06 4.83 6.52
Dissolved oxygen (%) 67.6 59.6 82.1 75.4 101.3
pH   8.35 8.05 8.35 8.24
Conductivity (µS/cm) 602 625 803 417 632
Total Dissolved Solids (ppm) 301 312 402 209 316
ORP (mV) 349.3 154.5 143.3 41.7 141.2
Turbidity Clear: Clear: Clear: Slightly milky: blue, grey, green Clear: slightly blue/grey
Alkalinity (mg/l CaCO₃) 193 (1.6N) - 206 (1.6N) 180 (1.6N) 192 (1.6N)
Alkalinity Tester (ppm CaCO₃) - - - 164 191

Data Analysis

There is a constant, significant flow in the rio Alis throughout the year. Fluctuations at this point reflect seasonal changes with significantly higher discharge recorded in June/July after the rainy season but by November it is much reduced as the dry season comes to an end.

At well over 3200m asl the DO readings at RT09A fall within the range to be expected.

The measurements for conductivity and total solids are slightly on the high side and may reflect the fact that this site lies below a more significant settlement - the small town of Alis. Sewage outfall and other pollutants from domestic waste may enter the channel here. However, despite this the readings for water quality are still good.

Average pH readings of above 8.0 are as expected. At these levels the alkalinity of the river is suitable for aquatic life.

Site Description

Sites RT09A lies in the arid temperate zone just below the small town of Alis at 3231m asl. It is located in the temperate zone in a narrow canyon. This being produced by rapid downcutting through a highly fractured upfold. The valley at this point is v-shaped with high sections of cliffs lining the valley. Above this point the valley widens out at the site of the settlement of Alis. The bed load in the river channel is comprised of fluvio-glacial boulders, gravels, and sands. The river flow in the Rio Alis is year-round, despite having been reduced by significant abstraction to supply the village of Alis.

There is limited agricultural cultivation. Historically, the terraced valleys would have been cultivated more intensively. Changes in agricultural production reflecting population decline in both the early period of Hispanic colonisation and, more recently, rural out-migration. There is limited pastoralism and field rotation employed for the production of potatoes and quinua.

The riverbanks are dominated by riparian scrub and small alders with stands of Eucalypts. Above the uneven flood-plain valley sides are dominated by arid scrub and relictual pacific woodlands in sheltered ravines. This site displays a fauna and flora typical of temperate elevations.

Chiguanco Thrush, House Wren and Hooded Siskin bird species remain. Cream-winged and White-winged Cinclodes, Striated Earthcreeper, Peruvian Sierra Finch, Plumbeous Sierra Finch, Band-tailed and Plain-coloured Seedeaters, and Black-throated Flowerpiercer are common here.

Tributary T09 - the Alis subcatchment. (Eustace Barnes) Tributary 09 - the Alis subcatchment. (Eustace Barnes)

Site T09A - the study site location. (John Forrest) Site RT09A - the study site location just below the town of Alis. (John Forrest)

Site T09A - the study site. (John Forrest) Site RT09A - the study site. (John Forrest)

Site T09A - View downstream from the study site. (John Forrest) Site RT09A - View downstream from the study site. (John Forrest)

Site T09A - View upstream from the study site. (John Forrest) Site RT09A - View upstream from the study site. (John Forrest)