2323 1. MIRADOR COPPER MINE 1.1 Description of the study area The Mirador Mine is located in the southern Ecuadorian Amazon, on the foothills of the Eastern Cordillera, between elevations ranging from 700 to 1,600 m a.s.l. The area receives annual precipitation between 2,800 and 4,000 mm, with mean monthly temperatures between 22 and 28 °C, and average monthly relative humidity between 87% and 91%. These conditions define a highly humid environment with intense weathering. Topography is predominantly mountainous, with slopes ranging from 40% to 70%. The hydrographic network shows a dendritic drainage pattern and forms part of the Quimi River basin, fed by the Wawayme and Tundayme rivers. Both the Mirador Mine and its main works and auxiliary infrastructure are located within these sub-basins. 1.2 Soil characteristics Soils in the area are weakly developed and of low fertility, with shallow A-horizon thicknesses ranging from 0.2 to 1 m. They present densities between 2.630 and 2.761 g/cm³ and, from a geotechnical standpoint, correspond to soils of low natural density and high susceptibility to erosion processes. The following soil types have been identified: • Low-hill soils (SCb): Reddish to yellowish hues and sandy-clay texture, derived from weathering and leaching of the Zamora Batholith. Surface runoff is moderate to rapid, while permeability is slow. High base saturation occurs in the surface layer due to organic matter, with low saturation at depth. These soils are acidic throughout the profile. • Medium- and high-hill soils (SCa): Kaolinitic, clayey, low-permeability, and poorly drained. These are leached soils of low fertility, acidic pH, shallow depth, and high erosion. • Alluvial terrace soils (St): Correspond to humid Inceptisols, with deficient natural drainage and frequent water near the surface. Surface horizons are gray to black, with redox features at less than 50 cm depth. • Mesa soils (SMs): Fine sandy or sandy-clay textures with predominance of residual quartz. Organic carbon content decreases with depth, and soils commonly become temporarily saturated with water, limiting agricultural use. These soils developed under denudational and aggradational environments, mainly influenced by geomorphological factors such as high rainfall, temperature, relief morphology, and fluvial dynamics. 1.3 Land-use capability Soil land-use suitability is primarily constrained by relief. In low-lying zones, soils are suitable for agriculture with limitations, allowing only short-cycle crops in valleys and river terraces of the Wawayme, Tundayme, and Quimi rivers. In undulating areas with moderate slopes, soils are suitable only for pasture and forest species due to shallow depth and high susceptibility to erosion. In areas with slopes greater than 40%, shallow to moderately deep soils predominate, with rock outcrops and potential or active water erosion; therefore, use is mainly restricted to forest protection purposes.
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