RC11 - Above Llapay HEP

Site Code: RC11. GPS: S12°33693, W75°825592. Elevation: 2921m asl.

Water Quality Data

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

RC11 July 2019 November 2019 November 2021
Season: Austral Winter Austral Summer Austral Summer
Date: 11.07.2019 20.11.2019 15.11.2021
Time: 12.45pm 11.30am 9.45
Width (m)   17.0 17.0
Depth (Av.) (m)   0.39 0.82
CSA (Av.) (m²)   6.55 13.94
Velocity (Av.) (m/s)   0.42 1.20
Discharge (Av.) (m³/s)   2.742 16.728
Riverbed sediment Cobbles & Boulders Cobbles & Boulders Mainly boulders
Temp. (Atmospheric) (°C) 24 23 17
Temp. (Water) (°C) 12.16 13.5 12.69
Atmospheric pressure (mbar) 640 736  
Dissolved oxygen (mg/l) 5.34 3.87 6.75
Dissolved oxygen (%) 68.9 62.7 88.8
pH 6.07 8.72 8.31
Conductivity (µS/cm) 453 445 579
Total Dissolved Solids (ppm) 228 222 289
ORP (mV) 350.5 119.6 143.9
Turbidity Clear: Clear: Clear:
Alkalinity (mg/l CaCO₃) 164 (1.6N) - 140 (1.6N)
Alkalinity Field Tester (ppm/ CaCO₃) - - -

Data Analysis

Discharge at this point along the Rio Canete has increased between July to November, suggesting that the rains had already started in the headwaters of this sub-catchment. The periods we have sampled as such fall principally within the dry season. However, rains in the high sierra do begin from mid-October.

At nearly 2900m asl the DO readings at RC11 are low but fall within the range to be expected for both July and November data sets and follow the catchment trend.

The conductivity readings at this site have been constant and follow the catchment trends. conductivity tends to be lower for the tributary sites than for main channel sites, as might be expected. Chemical weathering is much reduced in the sub-catchments as they are of shorter length. However, there are notable exceptions for T1a and T11a which require further investigation.

pH readings of 8.71-8.73 in November 2019, are as expected for a clean river. The July data requires confirmation.

Site Descriptions

Site RC11 lies in the Rio Canete valley at 2914m asl in the arid temperate zone. It is just above the El Platanal HEP (G2) and below confluence with the Rio Laraos. The valley at this point is narrow with a pronounced v-shaped profile and steep valley. River flow is year-round and fast at this point.

The site is similar to RC10, with little or no agricultural cultivation along this section of the Rio Canete, which is dominated by riparian Alders, tall thorn scrub and scattered clumps of Eucalyptus planted for timber and building materials. Above the narrow flood plain valley sides are arid, supporting a xeric vegetation with increased woody shrubs and trees lining some of the more sheltered ravines. The limited agricultural activity results from the narrow floodplain.

This site retains the typical avifauna of the lower elevations and shares the same fauna and flora as at RC10, with American Kestrel, Blue and yellow Tanager, Scrub Blackbird, Black-necked Woodpecker, Golden Grosbeak, Chiguanco Thrush, Golden-billed Saltator, House Wren and Hooded Siskin being species that now reflect more strongly the temperature zone community. The hillsides at this elevation have more extensive areas of relictual Pacific woodlands that typify vegetative associations higher up the valley. Arid slopes additionally hold Streaked Tit Spinetail, Cinereous Conebill, Band-tailed Seedeater and Band-tailed Sierra Finch.

RC11 View upstream Site RC11 - Study site location: just above LLapay HEP station. (John Forrest)

Site RC11 - the study site. (John Forrest) Site RC11 - the study site. (John Forrest)

RC11 View upstream Site RC11 - View upstream. (John Forrest)

RC11 View downstream Site RC11 - View downstream. (John Forrest)