1. Overview Paute River Basin

Paute River Basin is located south of the Ecuadorian Andes, a mountainous region of between parallel 2° 15’ and 3° 15’ south latitude and between the meridians 78° 30’ and 79° 20’ west latitude.

This basin is bounded to the north by the knot of Curiquingue, which divides the hoya of Cañar with hoya of Paute; to the south by the knot of Portete, which divides the hoya of Jubones with the hoya of Paute; to the east by the Eastern Cordillera of the Andes, which divides the Jungle with the Sierra, and to the west the occidental Cordillera of the Andes, which divides the Sierra Region with the cost. (UMACPA, 1995).

The catchment area of the basin covers an area of about 5,100 km² (closure of the basin in the reservoir Amaluza), its altitude varies from 1,824 m to 4,680 meters above sea level, despite its high altitude, there are no snow or ice; it is due to the proximity to the equatorial axis, which means that there are only two seasons: the dry and wet seasons. (Cellery, 2007)

Fig. N°1 Map Paute River Basin (UDA, 2008)

The hypsometric curve shows that the average elevation of the basin is 3,100 meters above sea level, and can be seen that generally consists of rugged peaks.

Figure N°2 Hypsometric curve Paute River Basin (Cellery, 2007)

Paute River Basin consists of the following watersheds:

Table N° 1 Main sub-watersheds of the Paute River Basin (UDA, 2008)

Figure N° 3 Major sub-basins that make up the Paute River Basin

2. Weather

The weather at Paute River Basin is influenced by three main airstreams:

Amazon Airstream: This current is entering the basin from Brazil to Ecuador (west-east), this is related with periods of higher rainfall, between March and October.

Pacific Ocean Airstream:

This current comes from the coast in a West-East direction, with two main rainy periods, the first one from February to March and the other less intense in October and November. The Niño and Niña phenomena have a major impact on this current.

Anticyclone from the South:

This airstream arrives in south-north direction and is what prevents precipitations in the southern part of the basin.

Types of Weather in the Basin

Mesotennico Equatorial Climate Semi-wet and Wet

It is located in the inter-Andean zone (Cuenca Valley, Paute, Sígsig, Gualaceo) and areas with higher altitudes of 3,000 to 3,200 meters above sea level, the annual average temperatures are between 12° to 20° C, while the maximum temperature is up to 30° C and the minimum is sometimes under 0° C, annual rainfall ranging from 500 mm to 2,000 mm, the relative humidity varies from 65% to 85% and the sunshine duration lasts from 1,000 to 2,000 hours per year. (Barrero, Ana Luz, 1989: 29).

Equatorial Cold Weather - High Mountain

It is located about 3,000 m high; the average temperature is 8° C, but it always fluctuate depending of the altitude, the maximum is 20° C and the minimum generally reaches values under 0° C; the rainfall depends of the slope and the height and could vary between 800mm to 2,000 mm; and the relative humidity is 80%, having a mountain forest vegetation and moorland (Barrero, Ana Luz; 1.989: 29)

Megatennico Tropical Weather Very Humid

Corresponds to the outer slopes of the two mountain ranges, is located between 1,000 m and 2,000 m above sea level, their temperature ultimately depends on the height, therefore the highlands have temperatures of about 10° C while the low may reach 20° C; has high rainfalls usually over 2,000 mm, and the relative humidity is high and nearly 90% (Barrero, Ana Luz, 1089: 29)

3. Precipitation Regimes on Paute River Basin

According to the study “Rainfall Variability and Rainfall-Runoff Dynamics in the Paute Ecuadorian river Basin – Southern Ecuadorian Andes” (Cellery, 2007) within the Paute River Basin it can be seen four monthly precipitation regimes, that occur within the basin, which are:

Bi-modal (BM2): This regime is the most extensive, covering about half of the basin in about 2,350 km², which represents almost 46% of the total basin area; this regime has two peaks, one in April and another in October. Within this scheme it can be seen the upper parts of the following catchments: Tarqui, Yanucay, Tomebamba, Burgay, Machángara and also part of the Santa Barbara basin and the eastern basins of Jubal and Pulpito.

Bi-modal (BM1): This regime is the second in coverage area, have a significant 36% of the entire are of the basin; it has two major peaks, one in April and another in October. Within this regime is the city of Cuenca.

Uni-modal 1 (UM1): This scheme covers a very small region in the basin of approximately 1,0%, with a rainy season from May to July with monthly values of 500 mm, so you can clearly see that it is an area of high rainfall. In the sector there is the Camp Guarumal.

Uni-modal 2 (UM2): This scheme covers 14% of the total area of the basin, the peak rainy period falls between May and July with values close to 180 mm. In this sector are located the Mazar and Pindilig Basins.

Figure N° 4 Precipitation regions within Paute River Basin (Cellery, 2007)

Figure N° 5. Monthly mean values of rainfall regimes on the Paute River Basin

The annual distribution of precipitation over the basin (annual isohyets map) is shown in the chart below

Fig. N° 6. Map of average annual Isohyets on Paute River Basin

4. Flow

 The flows entering the system Paute Integral consists of two parts: the first, the flow entering the reservoir Mazar (4,338 km² basin filler), these are produce by about 85% of the basin; and the second, the flows entering the reservoir Amaluza, formed mainly by the sub-basins Mazar, Jubal and Palmira.

The Mazar-Molino co-generation will increase the firm energy produced through the system, it is estimate that the system Mazar-Molino will yield a 6,380 GWh/year.

According to “Análisis de Caudales en los sitios de Presa Mazar-Ingapata y Amaluza” (Correa, 2001) there are found the following: curve length and curve of seasonal variation in the Mazar-Ingapanta Station which is the construction site of the Mazar Dam

Fig. N° 7. Flow duration curve at the dam site Mazar – Ingapata (Correa, 2001)

Fig. N° 8. Seasonal Variation Curve in the dam site Mazar – Ingapata (Correa, 2001)

The average and minimum monthly flows generated by the Mazar, Jubal and Palmira Basins, which are the water inflow to the reservoir Amaluza, are: 

Table N° 2. Average and minimum monthly inflow to the reservoir Amaluza, Sopladora Hydroelectric Project, Annex 2, Hydrology, Climatology and Sediment