RT02A - Lower Lincha

RT02A - Lower Lincha (Puente Huayllampi)

Site Code: RT02A. GPS: S12°80846, W75°896536. Elevation: 1109m asl.

Water Quality Data

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

T2a July 2019 November 2019 November 2021
Season: Austral Winter Austral Summer Austral Summer
Date: 10.07.2019 18.11.2019 10.11.2021
Time: 12.20pm 13.15pm 13.15pm
Width (m) 11.0 10.0 8.0
Depth (Av.) (m) 0.25 0.21 0.30
CSA (Av.) (m²) 2.76 2.10 2.40
Velocity (Av.) (m/s) 0.69 0.88 0.60
Discharge (Av.) (m³/s) 1.900 1.850 1.435
Riverbed sediment Cobbles & Boulders Cobbles & Boulders Mainly Boulders
Temp. (Atmospheric) (°C) 30 33 26
Temp. (Water) (°C) 17.90 24.23 23.89
Atmospheric pressure (mbar) 888 876  
Dissolved oxygen (mg/l) 7.14 5.81 6.55
Dissolved oxygen (%) 84.4 82.5 86.5
pH 5.86 9.30 8.84
Conductivity (µS/cm) 438 493 571
Total Dissolved Solids (ppm) 219 247 286
ORP (mV) 346.2 132.8 30.0
Turbidity Clear: slight green colouration Clear: Clear:
Alkalinity (mg/l CaCO₃) 108 (1.6N) - 95 (1.6N)
Alkalinity Field Tester (ppm/ CaCO₃) - - 79

Data Analysis

Discharge at this site is impacted by seasonal abstraction in the upper Rio Lincha. The scale of the sub-catchment and limited agriculture practised does nor reduce discharge to zero at present as happens in the Rio Vinac at sample site T1a.

At just over 1000m asl the DO readings at RT2a are as expected for both July and November data sets. The raised elevation and great fluctuations in daily temperature in such narrow and sheltered valleys will produce fluctuations in maximum absolute oxygen capacity and, in consequence, percentage saturation that therefore fluctuates with that rhythm. At DO levels from 6.13-7.27 mg/l and 75-86.4% oxygen saturation aquatic vertebrates survive and invertebrates thrive.

The conductivity at this site 437-491 (µS/cm) is higher than that recorded in the main channel.

At pH 9.29, as recorded in November 2019, readings are what would be expected and suitable for aquatic life and not approaching the tolerances of most aquatic vertebrates and invertebrates. The July data requires confirmation.

Site Description

Site T2a is located just below the town of Catahuasi in the arid upper tropics. The Rio Canete, at this point is downriver of limited intensively farmed lands. The use of pesticides and fertilizers is probably only higher in the various sub-catchments in the temperate zone. The valley has a narrow steeply v-shaped profile with a tall river cliff on the south bank, indicating earlier periods of flooding. As elsewhere in the drainage basin discharge is highly seasonal. Discharge measurements in February-March are considerably greater. The channel itself is choked with large boulders and rocks from land slides and earlier flooding events.

The banks are lined with scattered willow and some acacia scrub. The cultivation of crops is exclusively for subsistence farming in the marginal social groups forced onto the poorer soils. The production of maize, bananas dominate with smaller areas of avocado production. As with elsewhere in the catchment there is little or no natural vegetation remaining. The fauna and flora in the valley are depauperate with relictual west flanks endemics. The impact of water quality on the health of the environment and populations of wildlife occupying these lands is the subject of some aspects of our study here.

Tributary T02 - the Lincha subcatchment. (Eustace Barnes) Tributary 02 - the Lincha subcatchment. (Eustace Barnes)

Site T02A - the study site location. (John Forrest) Site T02A - the study site location: just below Puente Huayllampi. (John Forrest)

Site T02A - the study site. (John Forrest) Site T02A - the study site. (John Forrest)

Site T02A - View downstream from the study site. (John Forrest) Site T02A - View downstream from the study site. (John Forrest)

Site T02A - View upstream from the study site. (John Forrest) Site T02A - View upstream from the study site. (John Forrest)