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.