UPLAND EROSION AND SEDIMENT YIELD IN A LARGE ANDEAN DRAINAGE-BASIN

This preliminary effort toward developing a sediment budget for the primarily agricultural 3,531 km2 upper and middle drainage basin of the Rio Paute in Andean Ecuador focuses on the geographic locations of potential upland nonpoint sediment sources and compares upland soil erosion estimates based on the Universal Soil Loss Equation (USLE) with others extrapolated from rainfall simulation experiments. Although the USLE-based erosion estimates are consistently higher, spatial patterns of high and low erosion rate classes for the two approaches are relatively similar, differing primarily in urban areas and in peripheral high elevation zones. Relating sediment yield data to the upland erosion rates suggests that 17 to 41 percent of the eroded material leaves the basin annually.