RC02C - Puente Catapalla

Site Code: RC02C. GPS: -12.923484, -76.109352. Elevation: 550m asl.

Water Quality Data

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

RC02C November 2021 July 2022 October 2022
Season: Austral Summer Austral Winter Austral Winter
Date: 7.11.21 12.7.22. 22.10.22
Time: 17.45 18.30 18.00
Width (m) 60.0 31.0 46.4
Depth (Av.) (m) 0.24 1.00 0.436
CSA (Av.) (m²) 14.40 31.00 20.23
Velocity (Av.) (m/s) 0.55 0.80 0.56
Discharge (Av.) (m³/s) 7.920 24.800 11.329
Riverbed sediment Mainly cobbles Cobbles & Boulders Pebbles & Cobbles
Temp. (Atmospheric) (°C) 18.0 14.9 18.0
Temp. (Water) (°C) 22.72 18.93 21.63
Atmospheric pressure (mbar)   936 944
Dissolved oxygen (mg/l) 6.71 12.03 7.01
Dissolved oxygen (%) 82.20 139.70 84.15
pH 8.06 8.35 8.32
Conductivity (µS/cm) 535 444 457
Total Dissolved Solids (ppm) 268 222 228
ORP (mV) 121.5 125.95 113.78
Turbidity Clear: slightly opaque Clear: Clear: slightly greenish
Alkalinity (mg/l CaCO₃) 125 (1.6N) 139 (1.6N) 124 (1.6N)
Alkalinity Tester (ppm CaCO₃) (120) 117 110

Data Analysis

In November 2011 and June 2022, recordings were taken immediately upstream from the road bridge entrance to Catapalla while in October 2022 they were taken immediately upstream of the pedestrian bridge into Catapalla. The discharge varies considerably between July and October/November though the July figure may be based on an over-estimation (of depth & velocity). However, the river now contains the water that was abstracted at the Capillucas dam and has been returned to the river. This may also partly explain the higher July figure as more water is released from the dam following the rains earlier in the year in the headwaters. Conversely, by NOvember - the end of the dry season - levels would be expected to be lower.

There is some variation in the DO levels, with higher figures recorded in July.

Conductivity levels are as expected in the lower valley given that the river is now passing through several small towns and more expansive irrgiated areas draining into the river.

The average pH is over 8.0 which is ideal for aquatic life.

Site description

RC02C is situated upstream of Lunahuana and all its satellites. The river flows in a deep channel with steep banks, 5-10 metres high, lined with extensive river cane, scattered acacia and stands of stunted willow. In some places the banks have been stabilised to protect the road, bridges and property.

The river terraces upstream are intensively farmed with grapes and fruit trees dominating.